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Ont Health Technol Assess Ser. 2009; 9(14): 1–120.
Published online 2009 October 1.
PMCID: PMC3377525

Phakic Intraocular Lenses for the Treatment of Refractive Errors

An Evidence-Based Analysis
Health Quality Ontario

Executive Summary

Objective

The objective of this analysis is to review the effectiveness, safety, and cost-effectiveness of phakic intraocular lenses (pIOLs) for the treatment of myopia, hyperopia, and astigmatism.

Clinical Need: Condition and Target Population

Refractive Errors

Refractive errors occur when the eye cannot focus light properly. In myopia (near- or short-sightedness), distant objects appear blurry because the axis of the eye is too long or the cornea is too steep, so light becomes focused in front of the retina. Hyperopia (far sightedness) occurs when light is focused behind the retina causing nearby objects to appear blurry. In astigmatism, blurred or distorted vision occurs when light is focused at two points rather than one due to an irregularly shaped cornea or lens.

Refractive errors are common worldwide, but high refractive errors are less common. In the United States, the prevalence of high myopia (≤ −5 D) in people aged 20 to 39, 40 to 59, and 60 years and older is 7.4% (95% confidence interval [CI], 6.5% – 8.3%), 7.8% (95% CI, 6.4% – 8.6%), and 3.1% (95% CI, 2.2% – 3.9%), respectively. The prevalence of high hyperopia (≥ 3 D) is 1.0% (95% CI, .6% – 1.4%), 2.4% (95% CI, 1.7% – 3.0%), and 10.0% (95% CI, 9.1% – 10.9%) for the same age groupings. Finally, the prevalence of astigmatism (≥ 1 D cylinder) is 23.1% (95% CI, 21.6% – 24.5%), 27.6% (95% CI, 25.8% – 29.3%) and 50.1% (48.2% – 52.0%).

Low Vision

According to the Ontario Schedule of Benefits, low visual acuity is defined by a best spectacle corrected visual acuity (BSCVA) of 20/50 (6/15) or less in the better eye and not amenable to further medical and/or surgical treatment. Similarly, the Ontario Assistive Devices Program defines low vision as BSCVA in the better eye in the range of 20/70 or less that cannot be corrected medically, surgically, or with ordinary eyeglasses or contact lenses.

Estimates of the prevalence of low vision vary. Using the criteria of BSCVA ranging from 20/70 to 20/160, one study estimated that 35.6 per 10,000 people in Canada have low vision. The 2001 Participation and Activity Limitation Survey (PALS) found that 594,350 (2.5%) Canadians had “difficulty seeing ordinary newsprint or clearly seeing the face of someone from 4 m,” and the Canadian National Institute for the Blind (CNIB) registry classified 105,000 (.35%) Canadians as visually disabled.

Phakic Intraocular Lenses (pIOL)

A phakic intraocular lens (pIOL) is a supplementary lens that is inserted into the anterior or posterior chamber of the eye to correct refractive errors (myopia, hyperopia, and astigmatism). Unlike in cataract surgery, the eye’s natural crystalline lens is not removed when the pIOL is inserted, so the eye retains its accommodative ability. In Canada and the United States, iris-fixated (anterior chamber lenses that are anchored to the iris with a claw) and posterior chamber lenses are the only types of pIOLs that are licensed by Health Canada and the Food and Drug Administration, respectively.

Evidence-Based Analysis Method

Research Questions & Methodology

  1. What are the effectiveness, cost-effectiveness, and safety of pIOLs for the treatment of myopia, hyperopia, and astigmatism?
  2. Do certain subgroups (e.g. high myopia and low vision) benefit more from pIOLs?
  3. How do pIOLs compare with alternative surgical treatment options (LASIK, PRK, and CLE)?

Using appropriate keywords, a literature search was conducted up to January 2009. Systematic reviews, meta-analyses, randomized controlled trials, and observational studies with more than 20 eyes receiving pIOLs were eligible for inclusion. The primary outcomes of interest were uncorrected visual acuity (UCVA), predictability of manifest refraction spherical equivalent (MRSE), and adverse events. The GRADE approach was used to systematically and explicitly evaluate the quality of evidence.

Summary of Findings

The search identified 1,131 citations published between January 1, 2003, and January 16, 2009. Including a health technology assessment (HTA) identified in the bibliography review, 30 studies met the inclusion criteria: two HTAs; one systematic review; 20 pre-post observational studies; and seven comparative studies (five pIOL vs. LASIK, one pIOL vs. PRK, and one pIOL vs. CLE).

Both HTAs concluded that there was good evidence of the short-term efficacy and safety of pIOLs, however, their conclusions regarding long-term safety differed. The 2006 HTA found convincing evidence of long-term safety, while the 2009 HTA found no long-term evidence about the risks of complications including cataract development, corneal damage, and retinal detachment.

The systematic review of adverse events found that cataract development (incidence rate of 9.6% of eyes) is a substantial risk following posterior chamber pIOL implantation, while chronic endothelial cell loss is a safety concern after iris-fixated pIOL implantation. Adverse event rates varied by lens type, but they were more common in eyes that received posterior chamber pIOLs.

The evidence of pIOL effectiveness is based on pre-post case series. These studies reported a variety of outcomes and different follow-up time points. It was difficult to combine the data into meaningful summary measures as many time points are based on a single study with a very small sample size. Overall, the efficacy evidence is low to very low quality based on the GRADE Working Group Criteria.

For all refractive errors (low to high), most eyes experienced a substantial increase in uncorrected visual acuity (UCVA) with more than 75% of eyes achieving UCVA of 20/40 or better at all postoperative time points. The proportion of eyes that achieved postoperative UCVA 20/20 or better varied substantially according type of lens used and the type of refractive error being corrected, ranging from about 30% of eyes that received iris-fixated lenses for myopia to more than 78% of eyes that received posterior chamber toric lenses for myopic astigmatism.

Predictability of manifest refraction spherical equivalent (MRSE) within ± 2.0 D was very high (≥ 90%) for all types of lenses and refractive error. At most time points, more than 50% of eyes achieved a MRSE within ± 0.5 D of emmetropia and at least 85% within ± 1.0 D. Predictability was lower for eyes with more severe preoperative refractive errors. The mean postoperative MRSE was less than 1.0 D in all but two studies.

Safety, defined as a loss of two or more Snellen lines of best spectacle corrected visual acuity (BSCVA), was high for all refractive errors and lens types. Losses of two or more lines of BSCVA were uncommon, occurring in fewer than 2% of eyes that had received posterior chamber pIOLs for myopia, and less than 1% of eyes that received iris-fixated lens implantation for myopia. Most eyes did not experience a clinically significant change in BSCVA (i.e. loss of one line, no change, or gain of one line), but 10% to 20% of eyes gained two or more lines of BSCVA.

The pIOL outcomes for UCVA, predictability, BSCVA, and adverse events were compared with FDA targets and safety values for refractive surgery and found to meet or exceed these targets at most follow-up time points. The results were then stratified to examine the efficacy of pIOLs for high refractive errors. There was limited data for many outcomes and time points, but overall the results were similar to those for all levels of refractive error severity.

The studies that compared pIOLs with LASIK, PRK, and CLE for patients with moderate to high myopia and myopic astigmatism showed that pIOLs performed better than these alternative surgical options for the outcomes of:

  • UCVA,
  • predictability and stability of MRSE,
  • postoperative MRSE,
  • safety (measured as clinically significant loss of BSCVA), and
  • gains in BSCVA.

Correction of refractive cylinder (astigmatism) was the only outcome that favoured refractive surgery over pIOLs. This was observed for both toric and non-toric pIOLs (toric pIOLs correct for astigmatism, non-toric pIOLs do not).

Common adverse events in the LASIK groups were diffuse lamellar keratitis and striae in the corneal flap. In the pIOL groups, lens repositioning and lens opacities (both asymptomatic and visually significant cataracts) were the most commonly observed adverse events. These studies were determined to be of low to very low evidence quality based on the GRADE Working Group Criteria.

Keywords

Eye, myopia, hyperopia, astigmatism, phakic intraocular lens, LASIK, PRK, uncorrected visual acuity, best corrected visual acuity, refractive errors, clear lens extraction

Background

Objective of Analysis

The objective of this analysis is to review the effectiveness, safety, and cost-effectiveness of phakic intraocular lenses (pIOLs) for the treatment of myopia, hyperopia, and astigmatism.

Clinical Need and Target Population

Refractive Errors

Refractive errors occur when the eye cannot focus light properly. In myopia (near- or short-sightedness), distant objects appear blurry because the axis of the eye is too long or the cornea is too steep, so light becomes focused in front of the retina. Hyperopia (far sightedness) occurs when light is focused behind the retina causing nearby objects to appear blurry. In astigmatism, blurred or distorted vision occurs when light is focused at two points rather than one due to an irregularly shaped cornea or lens. (1)

Refractive errors are common worldwide. In the United States, they account for almost 80% of the visual impairment in people aged 12 and older. (1) Vitale et al. (1) estimated the prevalence of refractive errors in the United States using the National Health and Nutrition Examination Survey (NHANES). The results from Vitale et al. (Table 1) show the prevalence of myopia, hyperopia, and astigmatism varied by age. (1)

Table 1:
Prevalence of Refractive Errors in the United States

Low Vision

A variety of definitions exist for low vision. According to the Ontario Schedule of Benefits, low visual acuity is defined by a best spectacle corrected visual acuity (BSCVA) of 20/50 (6/15) or less in the better eye and not amenable to further medical and/or surgical treatment. (2) The Ontario Assistive Devices Program defines low vision by a BSCVA in the better eye in the range of 20/70 or less that cannot be corrected medically, surgically, or with ordinary eyeglasses or contact lenses. (3) The Canadian Ophthalmology Society defines low vision (partially sighted) as vision less than 20/60 that cannot be improved through medical or surgical means. (4) The World Health Organization and the International Council of Ophthalmology define low vision (referred to as moderate visual impairment) by a BSCVA of less than 20/70 to 20/160. (5)

There are a variety of estimates of the prevalence of low vision in Canada. Using the criteria of a BSCVA between 20/70 and 20/160, Maberley et al. (6) estimated that 35.6 per 10,000 people in Canada have low vision based on a sample of patients attending a physician’s office in Prince George, British Colombia. The 2001 Participation and Activity Limitation Survey (PALS) found that 594,350 (2.5%) Canadians had “difficulty seeing ordinary newsprint or clearly seeing the face of someone from 4 m,” and the Canadian National Institute for the Blind (CNIB) registry classified 105,000 (.35%) Canadians as visually disabled based on a study conducted between 1996 and 2001. (6) Cataract and visual pathway disease followed by age-related macular degeneration and other retinal diseases are the most common cause of low vision. (6)

Description of phakic intraocular lenses

A pIOL is a supplementary lens that is inserted into the eye to correct refractive errors (myopia, hyperopia, and astigmatism). Unlike in cataract surgery, the eye’s natural crystalline lens is not removed when the pIOL is inserted, so the eye retains its accommodative ability. (7)

Phakic IOLs may be inserted in the anterior or posterior chamber of the eye. (7) In Canada and the United States, iris-fixated (anterior chamber lenses that are anchored to the iris with a claw) and posterior chamber lenses are the only types of pIOLs that are licensed by Health Canada.

Design and Materials

Phakic lenses are designed to be permanent but can be exchanged or removed if necessary. The lenses are made of a variety of ultraviolet light absorbing materials including polymethyl methacrylate (PMMA), hydrophilic porcine collagen (< .1%), and hydroxyethyl methacrylate (HEMA). (7;8)

Phakic intraocular lenses may be spheric or toric in design. Spheric pIOLs are indicated for those with myopia or hyperopia with low astigmatism (less than 2.5 Diopters, D). Toric pIOLs are inserted at a specific angle to treat myopia or hyperopia with astigmatism (1.0 to 4.0 D). (9)

Regulatory Status

Canada

Four pIOLs are licensed by Health Canada (described in Table 2). While the Artisan and Verisyse lenses have different license numbers and distributors, they are the same lens. (10)

Table 2:
Phakic Intraocular Lenses Licensed by Health Canada

United States

The Food and Drug Administration (FDA) in the United States approved the Artisan/Verisyse pIOL (Ophtec, B.V.) in September 2004 for the correction of myopia (-3 to -20 D) and myopic astigmatism (astigmatism ≤ 2.5 D at the spectral plane). In December 2005, the FDA also approved the Visian ICL (Implantable Collamer Lens, Staar Surgical Company) to correct myopia (-3 to -20 D) and myopic astigmatism (astigmatism ≤ 2.5 D at the spectral plane). (11) Toric pIOLs for the treatment of astigmatism greater than 2.5 D are not licensed in the United States.

Alternatives

There are numerous treatments options for refractive errors of which eyeglasses are the least invasive and safest, followed by external contact lenses (hard and soft). More invasive, surgical techniques are also an option including numerous refractive keratoplasty procedures (surgical techniques that alter the shape of the cornea), corneal incision procedures, thermal procedures, intrastromal corneal ring segment implantations, and intraocular refractive surgery (7;12)

Refractive keratoplasty procedures are excimer laser ablation techniques such as laser assisted in-situ keratomileusis (LASIK), photorefractive keratectomy (PRK), laser assisted sub-epithelium keratomileusis (LASEK), and epi-LASIK. There are a number of complications associated with these procedures including surgical complications and problems with wound healing, flap-related complications, loss of BSCVA, unpredictability of refractive correction, severe night glare, excessive corneal thinning, and ectasia. Many of these complications are more common in patients with high refractive errors. (7;12-16)

Less common techniques include corneal incision procedures (e.g. radial keratotomy, arcuate keratotomy, and limbal relaxing incisions), thermal techniques (e.g. noncontact Holmium laser thermokeratoplasty and conductive keratoplasty with a high-frequency electric probe), and intrastromal corneal ring segments. (12)

There are two types of intraocular refractive surgery: pIOLs and clear lens extraction (CLE). Clear lens extraction, or refractive lens exchange, is the removal and replacement of the eye’s natural crystalline lens with an IOL for individuals that do not have a visually significant cataract. Disadvantages of this procedure include the loss of the eye’s accommodative ability, increased risk of retinal detachment, endophthalmitis, and maculopathy. (7;12)

Evidence-Based Analysis of Effectiveness

Research Questions

  • What are the effectiveness, cost-effectiveness, and safety of pIOLs for the treatment of myopia, hyperopia, and astigmatism?
  • Do certain subgroups (e.g. high myopia and low vision) benefit more from pIOLs and could they be used as a basis for potentially insurable indications?
  • How do pIOLs compare with alternative surgical treatment options (e.g. LASIK, PRK, and CLE)?

Literature Search

The Medical Advisory Secretariat completed a computer-aided search of electronic databases (OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, Cochrane Library, and International Agency for Health Technology Assessment/Centre for Reviews and Dissemination) to identify evidence related to pIOLs for the treatment of refractive errors published between January 1, 2003, and January 16, 2009. The search strategies are detailed in Appendix 1. Studies meeting the inclusion and exclusion criteria (listed below) were identified from the search results. Additional studies were identified from the reference lists of included studies.

Inclusion CriteriaExclusion Criteria
  • English language studies
  • HTAs, systematic reviews, meta-analyses, randomized controlled trials (RCTs), and observational studies
  • adult patients (≥18 years of age) with myopia, hyperopia, or astigmatism
  • primary outcome: UCVA or predictability of refractive correction
  • studies with clearly defined design, methods, population of interest and subject characteristics
  • studies published from January 1, 2003 to January 16, 2009
  • studies with fewer than 20 eyes for each refractive error type
  • pIOLs that are not licensed by Health Canada
  • pIOLs in combination with other surgical techniques (i.e., bioptics)
  • pIOLs for presbyopia
  • non-systematic reviews, letters, editorials, comments, and case reports
  • grey literature and abstracts
  • duplicate publications (superseded by another publication by the same investigator group with the same objective and data)
  • studies with insufficient data for analysis
  • animal and in vitro studies

Comparisons of Interest

  • pIOL versus LASIK
  • pIOL versus PRK
  • pIOL versus CLE

Outcomes of Interest

Primary OutcomesSecondary Outcomes
  • uncorrected visual acuity (UCVA)
  • predictability of manifest refraction spherical equivalent (MRSE)
  • adverse events
  • Efficacy Index
  • MRSE
  • stability of MRSE
  • predictability of manifest cylinder
  • stability of manifest cylinder
  • change in Best spectacle corrected visual acuity (BSCVA)
  • safety index
  • patient satisfaction
  • quality of life and vision

Methods of Analysis

Included studies were separated into two categories: pre-post observational case series evidence concerning the efficacy and safety of pIOLs and comparative case series comparing the effectiveness and safety of pIOLs with other refractive keratoplasty techniques. For the pre-post case series, results were stratified by lens type (iris-fixated or anterior chamber pIOL) and refractive error (myopia, hyperopia, and myopic astigmatism), then weighted means were calculated for each outcome. Results were also stratified by severity of myopia to examine the effectiveness of pIOLs in high myopia (myopia ≤−6 D). The results of the comparative case series were used to evaluate the effectiveness of pIOLs compared with LASIK, PRK, and CLE.

The FDA Ophthalmic Devices Panel has developed and recommended safety and effectiveness endpoints and target values for refractive surgery laser applications for investigational device exemptions. (17) These include effectiveness target values for UCVA and predictability of MRSE and safety target values for BSCVA and adverse events. The target values were originally developed for patients with low myopia (≥ −7 D) but were expanded in 1997 to include patients with high myopia (< −7 D), patients with hyperopia, and patients with myopic or hyperopic astigmatism. (18) In this analysis, the results of comparative studies and pre-post observational case series were compared with the FDA effectiveness and safety targets shown in Table 3 (where possible).

Table 3:
FDA Effectiveness and Safety Targets for Laser Refractive Surgery

Results of Evidence-Based Analysis

The database search yielded 1,131 citations published between January 1, 2003, and January 16, 2009. One reviewer, who was not blinded to author, institution, or journal of publication, evaluated the eligibility of the identified citations. Articles were excluded based on information in the title and abstract. The full texts of potentially relevant articles were obtained for further assessment. Figure 1 shows the breakdown of when and for what reason citations were excluded or included in the analysis.

Figure 1:
Citation Flow Chart

Two hundred forty-four of the identified citations were duplicates (the same article identified by more than 1 database) and excluded from further review. Twenty-nine studies (1 HTA, 1 systematic review, 20 pre-post observational studies, and 7 comparative studies) met the inclusion criteria. An additional citation (a HTA) was identified from other sources. Table 4 lists the level of evidence and number of studies identified. Characteristics of the included studies were extracted and are described in Tables 5 and 29.

Table 4:
Quality of Evidence of Included Studies

Summary of Existing Evidence

HTAs

Two international HTAs were identified in the literature. The first was a 2009 recommendation issued by the National Institute for Health and Clinical Excellent (NICE) Interventional Procedures Programme on the use of pIOLs for the correction of refractive errors based on a ‘rapid review’ of the technology. (20) Literature published up to May 14, 2008 was searched for efficacy and safety data yielding one meta-analysis (safety), two RCTs (pIOL efficacy compared with LASIK and PRK), two non-randomized controlled trials (efficacy), three case series (efficacy and safety), and three case reports (safety) for inclusion in the review. The analysis consisted of descriptive summaries of the studies without summary estimates for efficacy or safety outcomes. NICE concluded that there is good evidence of short-term efficacy and safety based on a large number of patients, but there is no data on the long-term risks of cataracts, corneal damage, or retinal detachment. (21) The second HTA identified was an updated review of implantable contact lenses for the correction of myopia published by the Australian and New Zealand Horizon Scanning Network in 2006. (22) The review included one RCT (pIOL efficacy compared with LASIK) and six case series reports evaluating safety and efficacy of pIOLs. The analysis consisted of descriptive summaries of the studies without summary estimates for efficacy or safety outcomes. They concluded that there is “convincing” long-term data for the safety of pIOLs. (22)

Both HTAs contained several important limitations. Firstly, both were based on rapid or horizon scanning literature reviews (as opposed to systematic reviews) and neither provided a comprehensive examination of the efficacy or safety of pIOLs. Secondly, there were no clear descriptions of the inclusion/exclusion criteria used, making it impossible to determine why the included studies were chosen while other identified studies were not. Finally, both HTAs contained only short qualitative descriptions of the included studies, while none of the data has been synthesized to create summary estimates of effect.

Systematic Reviews

A single systematic review by Chen et al. examined adverse events, particularly cataract development, after pIOL implantation. (23) The review included English language studies identified through Medline (National Library of Medicine, Bethesda, USA) and a bibliography search of materials published between 1966 and December 2006. Studies reporting clinical data or complications after implantation of anterior chamber, iris-fixated, and posterior chamber pIOLs were included in the review. Since there are no anterior chamber pIOLs licensed by Health Canada, results in Chen et al. related to these lenses were not included in the summary of the results in this report.(23) Similarly, a variety of the iris-fixated and posterior chamber lenses included in the systematic review are not licensed by Health Canada. Where possible, results are reported for only those lenses licensed by Health Canada.

Iris-Fixated Lenses

Chen et al. (23) included 50 studies with 2,781 eyes of at least 1,729 patients that received iris-fixated pIOLs, including 2,391 eyes that received lenses licensed by Health Canada. This was comprised of 2,075 Artisan/Verisyse IOL for myopia including the Worst myopic claw lens and the Artisan toric IOL for myopia, and 316 Artisan/Verisyse IOL for hyperopia including the Artisan toric IOL for hyperopia.1 (23) Figure 2A (on page 20) shows the combined incidence of complications (number of complications divided by total number of pIOLs) for the included studies, including the complications associated with iris-fixated lenses not licensed by Health Canada. The most common complication was glare/halos, which was reported for 244 eyes (8.8%). Ten other adverse events, including cataracts and uveitis, had incidence rates greater than 1%, the FDA safety target for adverse events (Figure 2A, Table 16). (17;18) Ninety-one eyes required additional operations due to complications other than cataract surgery. (23)

Figure 2:
(A) Complications following 2,781 iris-fixated pIOL implantations
(B) Complications following 2,396 posterior chamber pIOL implantations*
Table 16:
Safety Measured by Change in Best Spectacle Corrected Visual Acuity for Iris-Fixated and Posterior Chamber pIOLs

Cataracts were observed in 41 eyes comprising 20 new onset cataracts, 11 pre-existing progressive cataracts, and 10 pre-existing nonprogressive cataracts. Sixteen eyes (10 new onset and six pre-existing progressive cataracts) required pIOL explantation and cataract surgery. The mean time for development of new onset cataracts after pIOL implantation was 37.65 months. (23)

The overall incidence of cataracts (new onset and pre-existing progressive cataracts only) was 1.11%. The incidence of cataracts in eyes that received the Artisan/Verisyse pIOL was 1.1% for myopic eyes and 0.3% for hyperopic eyes. Of the new onset and pre-existing progressive cataracts, 24 occurred in patients that received the Artisan/Verisyse lenses. Nuclear sclerotic cataracts were the most common type of cataract (10/24) followed by cortical opacities (8/24) and posterior subcapsular cataracts (3/24). Three cataracts were of unknown type. The new onset nuclear sclerotic cataracts, however, were not attributed to the pIOL surgery because they occurred so long after occurred pIOL implantation. (23)

Endothelial cell loss due to contact between the pIOL and the cornea and/or chronic subclinical inflammation is another potential safety concern for iris-fixated pIOLs and suggests the need for regular, annual monitoring after pIOL insertion. (23)

Posterior Chamber Lenses

Chen et al. (23) included 49 studies of 2,396 eyes from at least 1,210 patients that received posterior chamber pIOLs. Of these eyes, 1,933 received lenses that are licensed by Health Canada (the Implantable Collamer Lens, ICL, STAAR Surgical Company); however, not all eyes received the current V4 model (589 eyes received an unspecified model and 467 received the V3 or earlier models).2 (23)

Figure 2B shows the combined incidence of complications for the included studies (including the posterior chamber lenses not licensed by Health Canada). The most common complication was pigment deposits on the pIOL, as reported in 260 eyes (10.85%). New onset or pre-existing progressive cataracts occurred in 230 eyes (9.60%). Glare and halos occurred in 142 eyes (5.93%). The incidence rates of five other adverse events including corneal edema and increased intraocular pressure were greater than 1%, the FDA safety target for adverse events (Figure 2B, Table 16). Additional operations due to complications other than cataract surgery were required for 157 eyes. (23)

Cataracts were observed in 262 eyes comprising 223 new onset cataracts, seven pre-existing progressive cataracts, and 32 pre-existing nonprogressive cataracts. Explantation of the pIOL and cataract surgery was required for 76 eyes with new onset cataracts and 6 eyes with pre-existing progressive cataracts. (23) The mean time for development of new onset cataracts after ICL pIOL implantation was 16.67 months (range, 1 – 44 months). (23)

The overall incidence of cataracts (new onset and pre-existing progressive) in eyes that received posterior chamber pIOLs was 9.60%. The incidence in the ICL group was 8.48% for myopic eyes and 11.05% for hyperopic eyes. Of the new onset and pre-existing progressive cataracts, 164 occurred in patients that received the ICL lens. Anterior subcapsular cataracts3 were the most common type of cataract observed (144/164), followed by nuclear sclerotic cataracts (6) and cortical opacities (3). Eleven cataracts were of unknown type. (23) Most of the anterior subcapsular cataracts were nonprogressive or slowly progressive, and 31.2% required surgery. (23)

Risk Factors for Cataract Development

Chen et al. (23) identified numerous risk factors for cataract development including age at time of implantation, high refractive errors, ocular trauma, inflammation (iridocyclitis), pre-existing opacities, inadequate lens vaulting, incompatible lens material, long follow-up duration, excessive postoperative steroid use, and pilocarpine use. The systematic review also found that the risk of cataract development is dependent on the location of the pIOL in the patient’s eye. Patients who received posterior chamber pIOLs were more likely to develop cataracts than patients who received iris-fixated pIOLs. This is thought to be because the posterior chamber lens is located closer to the crystalline lens where it is more likely to cause a pressure effect or metabolic imbalance of the lens. (23) Furthermore, different generations or models of a particular pIOL exhibit different rates of cataract development due design differences, particularly those related to adequate vaulting between the pIOL and the natural lens. (23)

While late-onset (≥ 1 year) cataracts are usually attributed to pIOL contact with the crystalline lens and/or repeated microtrauma resulting from IOL movement, surgical trauma (e.g. inadvertent lens touch or repositioning of an inverted pIOL, etc.) during pIOL implantation is the primary cause of new onset cataract development. In the systematic review, 14 of the 17 eyes that developed a cataract within 1 week of pIOL implantation had a history of intraoperative trauma. (23) In addition, several of the included studies observed a steep surgical learning curve, suggesting that surgeon experience may be important for reducing complication rates. (23)

MAS Systematic Review

Efficacy Studies: Low to High Refractive Errors

Twenty4 pre-post observational case series reporting efficacy and safety data for pIOLs were identified in the literature (summarized in Table 5). Only 19 of the 20 identified studies were included in this analysis. Guell et al. (27) was excluded because 36%5 (117/315) of eyes received additional refractive surgeries (LASIK, PRK, conductive keratoplasty, or arcuate keratotomy) after pIOL implantation to enhance refractive correction and the refractive results after the additional surgery were included in the reported visual outcomes thereby biasing the results (study details can be found in Appendix 2).

Table 5:
Characteristics of Included Pre-Post Efficacy Studies

In this section, the results are reported by outcome for each lens type and refractive error. When possible, data were combined to create summary estimates using weighted means (based on the sample size of the case series). It was not, however, always possible to combine data because studies reported a variety of outcomes and not all relevant outcomes were consistently reported in all studies. In addition, many studies reported results at different follow-up time points. For the outcomes or time points when it was not possible to combine the data, the resulting data values were often based on a study with a very small sample size, so these results must be interpreted with caution as they may be less accurate.

Uncorrected Visual Acuity

In the pIOL literature, UCVA is the main criterion for efficacy. (28) The proportion of patients who achieved UCVA of 20/20 or better and 20/40 or better were extracted from each study and used to calculate weighted means (Table 6).

Table 6:
Uncorrected visual acuity weighted mean calculations stratified by lens type and refractive error

Iris-fixated lenses for myopia

The UCVA results at 5 years were substantially higher than those from other time points. As these results are based on a single study with a small sample size (19 eyes), they must be interpreted with caution. Over the first 3 years, 20% to 34% of eyes achieved an UCVA of 20/20 or better. About 74% to 87% of eyes achieved an UCVA 20/40 or better over 10 years of follow-up after implantation.

Iris-fixated lenses for hyperopia

Only one study with a small number of eyes (22 eyes) reported UCVA results, so these results may be less accurate. (29) About 23% of eyes achieved 20/20 or better and 91% achieved 20/40 or better.

Posterior chamber lenses for myopia

Ninety-two to 94% of eyes achieved an UCVA of 20/40 or better during the first year of follow-up; however, over the next 2 years, this decreased to about 80% of eyes. About 56% of eyes achieved an UCVA of 20/20 or better during the first 2 years of follow-up, which decreased to 41% at 3 years.

Posterior chamber toric lenses for astigmatism

Uncorrected visual acuity results were only available for the first year of follow-up. About 80% of eyes achieved an UCVA of 20/20 or better and 95% achieved 20/40 or better.

FDA Targets

As shown in Table 7, iris-fixated lenses for myopia and hyperopia, and posterior chamber lenses for myopia and myopic astigmatism met the FDA effectiveness targets for UCVA for high myopia at all time points through follow-up. The lenses did not meet the criteria for low to moderate myopia at all time points, but as the study populations consist primarily of people with high refractive errors, the high myopia targets are more appropriate. Additionally, the FDA targets were set for eyes with good visual potential, that is, those that have a preoperative BSCVA of 20/20 or better. (39;40) Only 1 study (24) reported UCVA specifically for this cohort of eyes while the other studies included eyes with any preoperative BSCVA.

Table 7:
Comparison of UCVA Weighted Mean Results with FDA Targets for Iris-Fixated and Posterior Chamber pIOLs

Predictability of Manifest Refraction Spherical Equivalent

Predictability of MRSE (attempted versus achieved) is the measured by the percentage of eyes that are corrected within a target range (i.e., ± 0.5 D, ± 1.0 D, and ± 2.0 D) of emmetropia6, and it is an important measure of pIOL effectiveness. Fourteen studies (9;13;15;16;24-26;28-30;34;36-38) reported predictability, and the results of the weighted mean calculations7 stratified by lens type and refractive error are presented in Table 8.

Table 8:
Predictability Results Stratified by Lens Type and Refractive Error for Iris-Fixated and Posterior Chamber pIOLs

Iris-fixated lenses for myopia

The results reported at 5 years postoperatively were based on a single study (Silva et al. (13)), with very few eyes (19 eyes), these results are therefore less accurate and should be considered with caution, especially since the results are substantially higher than all other time points.

Predictability for each target range improved after 1 month follow-up. At each time point over 10 years (except 1 month), more than 90% of eyes were within ± 2.0 D of emmetropia. Predictability within ± 1.0 D ranged from 65 to 95% during the 10 year follow-up, and declined over time: in the first 2 years of follow-up, predictability ranged from 74 to 82%, which decreased to 65% at 6 years and to 69% at 10 years. Predictability within ± 0.5 D was also decreased over time, ranging from 64% at 3 months to 44% at 10 years.

Iris-fixated lenses for hyperopia

At 6 months follow-up, 100% of eyes were within ± 2.0 D of emmetropia, 86% were within ± 1.0 D, and 59% were within ± 0.5 D. These results may not be accurate, however, because they are based on only one study with a small sample size (Saxena et al. (29), 22 eyes) and should thus be interpreted with caution.

Posterior chamber lenses for myopia

Between 6 and 24 months follow-up, at least 96% of eyes were within ± 2.0 D of emmetropia. Over 3 years of follow-up, at least 86% of eyes were within ± 1.0 D of emmetropia, and 51 to 73% of eyes were within ± 0.5 D. While predictability within ± 0.5 D decreased over time (although an increase was reported at 3 years), predictability within ± 2.0 D increased.

Posterior chamber lenses for hyperopia

Predictability data was only available for 10 years postoperatively, with 100% of eyes within ± 2.0 D of emmetropia, 96% within 1.0 D, and 81% within ± 0.5 D. These predictability results are substantially higher than the 10 year postoperative predictabilities for iris-fixated lenses for myopia and the 3 year predictabilities for posterior chamber lenses for hyperopia. These results suggest high predictability of these lenses over time, but as they are based on only one study (Pesando et al. (15), 55 eyes), the results must be considered with caution.

Posterior chamber toric lenses for astigmatism

At 6 and 12 months follow-up, 100% of eyes were within ± 2.0 D of emmetropia, at least 93% were within 1.0 D, and at least 73% were within ± 0.5 D. Predictability appeared to be stable for at least the first year after implantation.

FDA Targets

As shown in Table 9, the predictability of posterior chamber lenses for myopia, hyperopia, and myopic astigmatism, as well as iris-fixated lenses for hyperopia, met or exceeded the FDA effectiveness targets for high and low to moderate myopia at all time points (the FDA targets are summarized in Table 3). Iris-fixated lenses for myopia met or exceeded the targets for high and low to moderate myopia at most time points.

Table 9:
Comparison of predictability results with FDA targets

Predictability Stratified by Severity of Myopia

Four studies (24;25;28;37) examined the effect of preoperative myopia severity on predictability. Senthil et al. (37) stratified predictability within ± 1.0 D results for iris-fixated lenses at 3 months using three levels of severity (Table 10), while Benedetti et al. (28) stratified predictability results for iris-fixated lenses for myopia at 4 months by two levels of severity (Table 11). The ICL in Treatment of Myopia Study Group reported 2 and 3 year predictability results from its clinical trial (24;25) for posterior chamber lenses for myopia stratified by 3 levels of severity (Table 12).

Table 10:
Predictability of MRSE Stratified by Severity
Table 11:
Predictability of MRSE Stratified by Severity
Table 12:
Predictability of MRSE Stratified by Severity

The stratified results showed that the proportion of eyes within target predictability varied by the preoperative severity of refraction. As preoperative severity of myopia increased, fewer postoperative eyes were within target predictability ranges, but the statistical significance of these differences is unknown. Despite the decreased predictability with severity, each stratified group still met or exceeded the FDA predictability target for high myopia.

Predictability of Manifest Cylinder

Toric lenses are designed to correct astigmatism, so the predictability of the manifest cylinder (similar to predictability of MRSE) is an important outcome for these lens types. As shown in Table 13, at least 85% of eyes were within ± 1.0 D of emmetropia. Predictability within ± 0.5 D was 59% at 6 months, which declined to 48% at 12 months.

Table 13:
Predictability of Manifest Cylinder for Posterior Chamber Toric Lenses for Astigmatism

Efficacy Index

The efficacy index (EI) is the ratio of the mean postoperative UCVA to the mean preoperative BSCVA. It is an important measure of pIOL efficacy because it takes into account the severity of patients’ refractive error, which can influence the effectiveness of the pIOL. (25) Eleven studies (13;14;26;28-32;34;36;37) reported either EI values or the data needed to calculate the EI.8 Weighted mean EIs were calculated using study sample sizes as the weights and the results are shown in Table 14.

Table 14:
Efficacy Index Calculations

For all lens types and refractive errors, the weighted mean EIs were less than 1.0. This indicates that the mean UCVA achieved postoperatively was worse than the mean preoperative BSCVA. Thus, patients achieved better vision with glasses or contact lens correction than pIOL insertion.

Iris-fixated lenses for myopia

The weighted mean EI for iris-fixated lenses for myopia ranged from 0.43 to 0.95 over 10 years of follow-up. The 3 and 5 year time points are based on only one study with very few eyes (Silva et al. (13), 19 eyes), thus these values must be interpreted with caution, especially because they are much lower than at the other time points. Excluding the results from Silva et al. (13), overall, the EI increased over the first 2 years then decreased slowly about 6 to 10 years after implantation.

Iris-fixated lenses for hyperopia

Over 3 years of follow-up, the EIs for iris-fixated lenses for hyperopic ranged from 0.67 to 0.76. The results also showed that the EI decreased over time. Compared with iris-fixated lenses for myopia, hyperopic lenses had lower EIs and a faster decline over time. These values are, however, based on only one study, Pesando et al. (15), with few eyes (small initial sample size and > 50% loss to follow-up at 3 years), so these results may be less accurate and the statistical significance of this trend is not known.

Posterior chamber lenses for myopia

For posterior chamber lenses for myopia, EI ranged from 0.69 to 0.99 over 4 years follow-up (all but one value are > 0.84). Overall, EI appears to increase over the first 2 years and then decrease over the subsequent 2 years. The accuracy of the results at 1 and 2 years is questionable, however, as the calculated weighted means include data from Lackner et al. (32), which was to heavily weighted because the preoperative sample size (65 eyes) was used as the weight since loss to follow-up beyond 6 months was not reported in the paper.9 Lackner et al. also had a larger sample size than the other included studies [n at 2 years was 25 and 12 in Alfonso et al. (30) and Chang et al. (31), respectively], which means that it may have unduly influenced the results. (When the Lackner data is included, the weighted mean EI at 2 years is 0.87, but when it is excluded, the EI is 0.97.)

Posterior chamber toric lenses for astigmatism

At 6 months follow-up, posterior chamber toric lenses for astigmatism had a high EI (0.94).

An important caveat to consider when examining the EI data is that some studies calculated the EI using the preoperative mean BSCVA for all eyes included in the study, while some studies used the preoperative mean BSCVA for only those eyes with paired data at the postoperative time point. Using paired data could bias the results if the eyes that were followed for longer experienced bigger improvements than those lost to follow-up. For example, in Chang et al. (31), the mean preoperative BSCVA (decimal acuity) for eyes with paired data was 0.84 and 0.75 at 12 and 24 months postoperatively (data from author). Therefore, EI was higher at 24 months than 12 months, but not because of increasing EI over time, but rather the differences between the patients who were followed for 24 months compared to those who were only followed to 12 months.

Manifest Refraction Spherical Equivalent

Table 15 displays the comparison of the preoperative and postoperative MRSE for each study. It was not possible to combine MRSE results into a summary measure, so the results for each study are presented separately. Only two studies had a postoperative MRSE greater than 1 D (Shen et al. (33), −1.79 ± 1.13 D; Lackner et al. (32), −1.77 ± 2.17D). Some patients in these studies, however, were not targeted for emmetropia because their preoperative myopic error exceeded the maximum corrective strength of pIOLs (pIOLs are licensed to correct myopia up to −20 D).

Table 15:
Summary of Mean Pre- and Postoperative Manifest Refraction Spherical Equivalent for Iris-Fixated and Posterior Chamber pIOLs

Safety

Best Spectacle Corrected Visual Acuity

Preservation of BSCVA is a main criterion for assessment of the safety of a refractive surgical procedure. (24) A change in one Snellen line is not clinically significant as it is within the range of normal individual variation for repeated measurements. (41;42) The loss of more than one line of BSCVA is considered the standard for safety, so that after pIOL implantation, a patient will at least retain the same level of vision with spectacle/contact correction. (42) Table 16 and Figures 3 to to77 show the proportion of eyes that gained or lost lines of BSCVA after pIOL implantation. Since change in BSCVA was not reported in all studies and most reported results for different postoperative time points, it was only possible to calculate a weighted mean for the 3 month follow-up for iris-fixated lenses for myopia and 12 month follow-up for posterior chamber lenses for myopia.

Figure 3:
Change in Best Spectacle Corrected Visual Acuity over Time for Iris-Fixated Lenses for Myopia
Figure 7:
Change in Best Spectacle Corrected Vision over Time for Posterior Chamber Lenses for Myopic Astigmatism

Approximately 77% to 90% of eyes did not experience a clinically significant change in BSCVA (loss of one line, no change, or gain of one line). Very few eyes lost two or more lines of BSCVA after pIOL implantation. The highest loss of BSCVA was observed in the posterior chamber lenses for myopia at 24 months follow-up (1.6% of eyes lost ≥2 lines of BSCVA).

Approximately 10% to 20% of eyes gained two or more Snellen lines. Based on the observed trends for iris-fixated lenses for myopia and hyperopia and posterior chamber toric lenses for astigmatism, the number of eyes that gain two or more lines of BSCVA may increase slightly over time. However, given the small increases and limited number of eyes at some time points, this trend must be interpreted with caution.

United States Food and Drug Administration Target Values

The FDA defined safety targets for loss of BSCVA: loss of two or more lines of BSCVA should occur in fewer than 5% of eyes. (17;39;40) All of the lenses met this safety target (Table 17).

Table 17:
Comparison of FDA Targets for Loss of BSCVA with pIOL Results

Safety Index

The safety index (SI) is the ratio of the mean postoperative BSCVA to the mean preoperative BSCVA. Table 18 shows the weighted mean SI over time after pIOL insertion.

Table 18:
Safety Index Calculations Stratified by Lens Type and Refractive Error

Iris-fixated lenses

The SI for iris-fixated lenses for both myopia and hyperopia declined over time. While the observed decline was more rapid for hyperopic lenses, the statistical significance of this trend is not known. The results for hyperopia data are based on one study with a small sample size (Saxena et al. (29), 22 eyes), so must be considered with caution.

Posterior chamber lenses

The SI for posterior chamber lenses for myopia is also based on only one study with a small sample size (Alfonso et al. (30), 25 eyes). Lackner et al. (32) reported a safety index of 1.31 for posterior chamber myopic lenses, but this SI was averaged over the entire observation period (mean follow-up 21.9 ± 15.94 months), and so could not be included in the weighted mean SI calculations.

Figure 4:
Change in Best Spectacle Corrected Visual Acuity over Time for Iris-Fixated Lenses for Hyperopia
Figure 5:
Change in Best Spectacle Corrected Visual Acuity over Time for Posterior Chamber Lenses for Myopia
Figure 6:
Change in Best Spectacle Corrected Visual Acuity over Time for Posterior Chamber Lenses for Hyperopia

Adverse Events

Chen et al. (23) conducted a systematic review of the literature on adverse events associated with pIOLs. Their focus was cataracts but all reported complications were included. Glare/halos were the most common complication reported in the iris-fixated lens group and pigment deposits on the pIOL in the posterior chamber lens group. A summary of the systematic review and incidence of complications are provided in the Summary of Existing Evidence, Systematic Review section of this report.

More than 30 adverse events including cataract development, glare/halos, macular holes, iritis, corneal edema, and increased intraocular pressure were reported in the 19 included pre-post observational case series. As the adverse events were reported differently by each study and the completeness of reporting and examinations varied, the results were not combined into summary rates. A complete list and description of these adverse events can be found in the data tables in Appendix 4. The adverse event data was limited in that some of the serious complications, such as retinal detachment and cataract development, are more common in people with high myopia. Without a control group, it is difficult to determine if these complications are due to the pIOL insertion or the patient’s high myopia.

The FDA specified safety targets for adverse events: for each type of adverse event, less than 1% of eyes should experience the event. (17;18) This target applies to myopia (with or without astigmatism) and hyperopia. Twelve complications reported in the systematic review by Chen et al. (23) exceeded this safety target (Table 19).

Table 19:
Adverse Events that Exceed the FDA Safety Target from Chen et al. (23)

In the pre-post observational case series, many of the adverse event rates exceeded this safety target as well but rates varied substantially between studies. The highest adverse event rates (those ≥ 10%) were observed for:

  • postoperative inflammation (cells and flare) in Stulting et al. (26) (40.3% at 1 day postoperatively),
  • pigment deposits on lens in Shen et al. (33) (100% at 1 day),
  • iritis in ITM 2003(24)(19.3% at 1 day), lens opacification in Lackner et al. (32) (33%),
  • blunt trauma in Moshirfar et al. (16) (11.6%),
  • increased intraocular pressure in Senthil et al. (37) (10%),
  • persistent iris atrophy in fixation area of hepatic in Saxena et al. (29) (11.8%),
  • asymptomatic ovalization of the pupil in Stulting et al. (26)(13% at 1 day), and
  • corneal edema in Stulting et al. (26) and ITM 2003 (24) (19.4% and 11.3% at 1 day, respectively).

Higher complication rates were more common in the smaller studies.

Endothelial Cell Density and Loss

The posterior surface of the cornea is covered by a layer of endothelial cells. Adequate endothelial cell density (ECD) is important to maintain a clear cornea. Implantation of IOLs, particularly those that are inserted in the anterior chamber, can result in loss of these endothelial cells, which is an important safety concern. Endothelial cell loss (ECL) has been attributed to contact between pIOLs in the anterior chamber, as well as corneal endothelial remodelling after surgical trauma. (43) Ten studies reported ECD, summarized in Table 20. Preoperative ECD varied substantially across studies, so the results were not combined into a summary weighted mean ECD. Table 21 summarizes the ECL (calculations based on only patients with paired data at the preoperative and postoperative time points) reported by nine studies. Some studies took into account annual physiologic cell loss unrelated to pIOL implantation (loss ranged from 0.5 – 0.6%). Endothelial cell loss also varied substantially between studies.

Table 20:
Endothelial Cell Density
Table 21:
Endothelial Cell Loss

Learning Curve

In the systematic review, Chen et al. (23) observed that several of the included studies identified higher rates of adverse events when a surgeon first starts to perform the procedure. A learning curve associated with lower complication rates as surgical skills and experience increased was also observed in two of the studies included in this analysis. (26;37)

Patient Satisfaction

Four studies measured postoperative patient satisfaction. (9;24;25;28). Benedetti et al. (28) reported that 100% of patients were satisfied with the results of their pIOL implantation; the other three studies reported satisfaction segmented by three categories (Table 22). Overall, more than 90% of patients were very/extremely satisfied with the results of the pIOL implantation, and satisfaction remained high over time (3 years).

Table 22:
Satisfaction with results of pIOL implantation

One study covered above (ITM, 2004) also reported satisfaction stratified by preoperative MRSE. The results showed that satisfaction varied by severity of preoperative MRSE: patients with more severe myopia reported less satisfaction with the results (very/extremely satisfied: ≥ -7 D, 95.8%; < -7 to -10 D, 94.3%; < -10 D, 88.4%), and only patients in the most severe group of myopia reported dissatisfaction with their results (2 eyes, 1.4%). (25)

Quality of Life and Vision

The ICL in Treatment of Myopia (ITM) Study Group assessed quality of vision after pIOL implantation using a standardized subjective questionnaire. (25) Changes in postoperative symptoms at 1 and 3 years were compared with preoperative levels. Overall, 76% to 80% of patients did not experience a change in glare, halos, night vision, or night driving symptoms, while more than 97% of patients did not experience a change in double vision. (24;25)

In Benedetti et al. (28), quality of life was assessed using a subjective survey at 4 months postoperatively. Overall, 95% of patients reported increased quality of life after pIOL implantation. Most patients reported improvements in several aspects of their daily lives including reading (87%), watching TV (89%), shopping (81%), playing sports (87%), and driving during the day (88%). However, 17% of patients reported worse night driving and 6.4% reported halos and/or medium intensity nocturnal glare. (28)

Pesando et al. (15) assessed quality of life and vision using a subjective questionnaire before pIOL implantation and at 6 and 12 months postoperatively. Approximately 89% of patients reported good quality of vision and improved quality of life. The number of patients who reported halos under scoptic light decreased over time (6 months, 70%; 1 year, 6%). The two patients who reported halos at 1 year had overly vaulted10 pIOLs, which the authors believed to be the cause of the decreased quality of vision. (15)

Efficacy Studies for High Refractive Errors

Preoperative severity of myopia, hyperopia, or astigmatism is an important factor that can influence the efficacy and safety of pIOLs. (24;25) The American Academy of Ophthalmology’s Preferred Practice Pattern Guidelines: Refractive Errors & Refractive Surgery (12) classify the severity of refractive errors as follows:

Myopia

  • Low to moderate: greater than −6.00 D
  • High: less than −6.00 D

Hyperopia and Astigmatism

  • Low to moderate: less than 3.00 D
  • High: greater than 3.00 D.

Except when studies have reported their results stratified by severity (e.g. four studies reported predictability of MRSE stratified by severity of myopia), it was not possible to compare the results for high myopia with moderate and/or low myopia as many of the studies included patients with a wide range of myopia from low to high. To isolate the efficacy of pIOLs for high refractive errors, results were reexamined including only the studies with high myopia (defined as those studies with a preoperative mean MRSE of −6 D or higher) and high hyperopia (defined as preoperative mean MRSE ≥ 3 D) patient populations (Table 23).

Table 23:
Summary of Studies with Patient Populations with High Refractive Errors for Iris-Fixated and Posterior Chamber pIOLs

Uncorrected Visual Acuity

Weighted means could not be calculated for UCVA for high myopia or hyperopia since not all studies reported this outcome and those that did didn’t report for the same follow-up periods, lens type, or refractive error.

Overall, the results for both iris-fixated and posterior chamber lenses exceeded FDA effectiveness targets for UCVA for high myopia11. This is particularly impressive as many of the eyes had a preoperative BSCVA worse than 20/20. It was not possible to separate the results for the cohort of eyes with good visual potential from other eyes, except for the ITM, 2003 (24) study in which this data is provided.

Iris-fixated lenses for high myopia

At most of the follow-up visits, 10% to 24% of eyes achieved an UCVA of 20/20 or better. At 5 years, 74% of eyes had UCVA of 20/20 or better, however, this result was based on one study with a small sample size [Silva et al. (13), 19 eyes], so it must be interpreted with caution. Approximately 80% to 95% of eyes achieved UCVA of 20/40 or better over the 5 year follow-up period. The FDA effectiveness target for UCVA for high myopia was exceeded at all time points.

Iris-fixated lenses for high hyperopia

Only one small study (22 eyes) reported UCVA results for high hyperopia. Saxena et al. (29) reported that 23% of eyes achieved an UCVA of 20/20 or better and 91% 20/40 or better at 6 months postoperatively. These results exceed the FDA effectiveness target for UCVA for hyperopia.

Posterior chamber lenses for high myopia

Ninety-four percent of eyes achieved an UCVA of 20/40 or better at 3 months, exceeding the FDA effectiveness target for UCVA for high myopia. This was the only follow-up time point that was reported, and it was based on only one study with a limited sample size [Shen et al. (33), 36 eyes], thus results must be interpreted with caution.

Predictability of Manifest Refraction Spherical Equivalent

Predictability of MRSE was reported in eight studies (13;15;16;24;25;28;29;38). Weighted means were calculated for high myopia (Table 24), but as only one study for each lens type was identified for hyperopia, results could not be pooled for high hyperopia (Table 25).

Table 24:
UCVA for Iris-Fixated and Posterior Chamber Lenses for High Refractive Errors
Table 25:
Predictability for Iris-Fixated and Posterior Chamber Lenses for High Myopia

Iris-fixated lenses for high myopia

The predictability trends for high myopia are similar to those for all myopia. Predictability improved over the first 12 months, especially over the first few months. After 3 months, 56% to 74% of eyes were within ± 0.5 D of emmetropia and almost all eyes were within ± 2.0 D. At all time points beyond 1 month, the results exceeded the FDA effectiveness targets for predictability for high myopia. The results at 60 months are based on a small number of eyes (19 eyes), so these values must be interpreted with caution.

Posterior chamber lenses for high myopia

Fifty percent to 60% of eyes were within ± 0.5 D of the emmetropia at all time points, and almost all eyes (about 95%) were within ± 2.0D. At all time points, the results exceeded the FDA effectiveness target for predictability for high myopia.

High Hyperopia

Iris-fixated lenses for high hyperopia

Predictability of MRSE was only available for 6 months postoperatively. One hundred percent of eyes achieved predictability within ± 2.0 D of emmetropia and 60% of eyes were within ± 0.5 D. These results exceeded the FDA effectiveness targets for predictability for hyperopia.

Posterior chamber lenses for high hyperopia

Ten years following implantation of the pIOL, 81% of eyes were within 0.5 D of emmetropia and more 100% within 2.0 D. These results exceeded the FDA effectiveness targets for predictability of hyperopia.

Table 26:
Predictability for Iris-Fixated and Posterior Chamber Lenses for High Hyperopia

Efficacy Index

Weighted mean EIs could not be calculated for high myopia or hyperopia because only a few studies reported this outcome and reported time points did not overlap across studies/lens types.

Iris-fixated lenses for high myopia and hyperopia

The EI for high myopia ranged from 0.43 to .86 over the 5 year follow-up period. The results at 3 and 5 years are based on one study with a small sample size (high myopia: 3 years, 20 eyes; 5 years, 19 eyes; high hyperopia: 3 years, 10 eyes), so results must be interpreted with caution. EI decreased over time from 0.76 at 6 months to 0.67 at 3 years, but the statistical significance of this trend is unknown.

Posterior chamber lenses for high myopia

EI was greater than 0.90 at 1 and 2 years follow-up, but these results are based on one study with a small sample size (12 eyes at 2 years), thus must again be interpreted with caution.

Table 27:
Efficacy Index for Iris-Fixated and Posterior Chamber Lenses for High Myopia and Hyperopia

Safety: Change in Best Spectacle Corrected Visual Acuity

High Myopia

Weighted means could not be calculated for BSCVA for high myopia because only a few studies reported this outcome, and the reported time points did not overlap across studies. Furthermore, data was only available for iris-fixated lenses for high myopia (see Table 28 and Figure 8).

Table 28:
Change in Best Spectacle Corrected Visual Acuity for Iris-Fixated Lenses for High Myopia
Figure 8:
Change in Best Spectacle Corrected Visual Acuity over Time for Iris-Fixated Lenses for High Myopia

No eyes lost two or more lines of BSCVA, so the FDA safety target for loss of BSCVA was met. About 80% to 85% of eyes did not experience a clinically significant change in BSCVA, while the other 15% to 20% gained two or more lines of BSCVA. At 4 months, however, 43% of eyes reported a gain in two or more lines of BSCVA, but since the result is substantially higher than the other results, it must be considered with caution.

High Hyperopia

Weighted means could not be calculated for BSCVA for high hyperopia as only two studies reported this outcome and the reported time points did not overlap (Table 29 and Figures 9 and and1010).

Table 29:
Change in Best Spectacle Corrected Visual Acuity for Iris-Fixated and Posterior Chamber pIOLs for High Hyperopia
Figure 9:
Change in Best Spectacle Corrected Visual Acuity over Time for Iris-Fixated Lenses for High Hyperopia
Figure 10:
Change in Best Spectacle Corrected Visual Acuity at 120 Months for Posterior Chamber Lenses for High Hyperopia

No eyes lost 2 or more lines of BSCVA, so the FDA safety target for loss of BSCVA was met. About 80% to 91% of eyes did not experience a clinically significant change in BSCVA12, while the other 9% to 20% gained 2 or more lines of BSCVA. The results for iris-fixated lenses for based on only one study with a small sample size (10 eyes at 3 years), so these results may be less accurate.

Safety: Safety Index

High Myopia and Hyperopia

The SI was only reported in two studies, one for high myopia and one for low myopia, thus weighted means could not be calculated (Table 30). Over time, the SI was higher for posterior chamber lenses for high myopia compared with iris-fixated lenses for high hyperopia, but the statistical significance of this trend is unknown. The results for high myopia are based on one study with a very small sample size (10 eyes at 3 years), so these results must be interpreted with caution.

Table 30:
Safety Index for High Refractive Errors

General Limitations: Efficacy Studies

Several limitations apply to most or all of the included case series. First, eyes were used as the unit of analysis rather than the number of patients in all 20 studies. Many of the patients enrolled in the studies received pIOLs in both eyes and the results from each eye are included in the reported results. This resulting study sample sizes may be close to double the number of participating patients. Measurements from two eyes of the same individual are, however, correlated (within-subject correlation), violating the assumption of independent data units on which most standard statistical significance tests are based. Thus, the variability of the data is decreased and the statistical power of the study is increased, which may result in falsely precise confidence intervals and small P values. (44-46) Stulting et al. (26) took within-subject correlation into account in their analysis and included results for only the first eye that received the pIOL in the refractive outcomes (data from all eyes were included for safety outcomes). The other 19 studies did not attempt to correct for within-subject correlations. Accordingly, reported results may be falsely precise and some of the observed statistically significant results may be spurious.

Second, many of the studies exhibited high loss to follow-up (> 30%), especially beyond 6 or 12 months. This limits our understanding of long-term outcomes as well our confidence in the results. While some of the retrospective case series had very good follow-up, this was generally because patients were only included in the study if they had a minimum follow-up length. This selection bias could affect the results if patients with poorer outcomes were more likely to have shorter follow-up durations than those with good outcomes, for instance if patients have the pIOLs removed before the minimum time period requirement.

Third, selection bias was a potential concern in some of the studies. Ten studies did not enrol consecutive patients, which could be a concern if the enrolled patients did not represent the average patient seeking pIOL implantation, but rather a subset of patients who were more likely to experience the best outcomes after pIOL implantation.

Finally, the literature is limited by the study design itself. All 20 studies are pre-post case series and do not have a contemporaneous control group, which decreases the quality of evidence. This is addressed more in the next section on the GRADE Quality of Evidence.

GRADE Quality of the Evidence: Efficacy Studies

A summary of the GRADE quality of the evidence for each lens type and refractive error is provided in Table 31. Due to serious limitations in study quality and sparse data for some outcomes (further details can be found in the GRADE tables in Appendix 3), the pIOL efficacy literature was determined to be of low or very low quality.

Table 31:
Summary of GRADE Quality of Evidence for Efficacy Studies

Comparative Studies

Seven studies compared posterior chamber pIOLs with other surgical techniques (summarized in Table 32). Of note, only one RCT was found to meet the inclusion criteria. Characteristics of these studies are described in Table 32. The results for each study are examined below. Limitations specific to individual studies are included within the study summaries, while those limitations that apply to most or all of the studies are discussed in the General Limitations section (page 75). No studies comparing iris-fixated pIOLs with other surgical techniques that that met the inclusion criteria were identified.

Table 32:
Characteristics of Included Comparison Studies

Phakic Intraocular Lenses Compared with LASIK for Myopia

Table 33 provides a summary of the 1 week, 1 month, 6 months, and 12 months postoperative results from the studies which compared pIOLs with LASIK for myopia.

Table 33:
Summary of Outcomes from the Studies Comparing pIOLs with LASIK for Myopia

Moderate Myopia: Sanders and Vukich, 2006 (47)

Sanders and Vukich, 2006 (47) conducted a case series that compared pIOLs with LASIK for moderate myopia (−4.00 – −7.88 D). The LASIK group consisted of 1,678 eyes from patients who received their surgery at the Davis Duehr Eye Center in Wisconsin, while the ICL group consisted of 144 eyes from the US FDA multicenter clinical trial of the Implantable Collamer Lens (STAAR Surgical). (47) The study groups were significantly different with respect to a several characteristics including mean age (P< .001), preoperative myopia (P< .001), cylinder (P< .001), and UCVA (P < .001).

Uncorrected Visual Acuity

The proportion of eyes that achieved an UCVA of 20/20 or better was significantly greater in the LASIK group at 1 day (LASIK, 38%; pIOL, 28%; P= .019). There was no significant difference between the groups at 1 week and 1 month, but at 6 months the proportion of eyes seeing 20/20 or better was significantly higher in the pIOL group. (47)

Beyond the first postoperative day when the proportion of eyes that achieved an UCVA of 20/40 was significantly higher in LASIK group (pIOL, 69%; LASIK, 92%; P< .001), there were no significant differences in the proportion of eyes that achieved an UCVA of 20/40 or better between the two groups. The FDA effectiveness targets for UCVA for low and high myopia were met or exceeded in the LASIK group at all time points and in the pIOL group after 1 day. (17;18;47)

Predictability

The proportion of eyes that achieved refraction within ± 0.5 D of emmetropia was similar in both groups at all time points, except for 6 months at which time the pIOL group was significantly higher than the LASIK group. Similarly, predictability within ± 1.0 D was significantly different between the two groups only at the 6 month visit. Predictability of the MRSE within ± 0.5 and 1.0 D met the FDA targets for high myopia in both the LASIK and pIOL groups. (17;18;47)

Manifest Refraction Spherical Equivalent

The preoperative mean MRSE was significantly higher in the pIOL group (pIOL, −6.4 ± .009 D; LASIK, −5.6 ± .03 D; P < .001). At 1 week postoperatively, the mean MRSE was significantly lower (closer to emmetropia) in the LASIK group than the pIOL group. At 3 and 6 months, however, the mean MRSE was lower in the pIOL group and this difference was significant at 6 months. (47)

Stability of Refraction

The stability of refraction (proportion of eyes with ≤ 0.5 change) was significantly greater in the pIOL group than the LASIK group at all time points. Stability of refraction within 1.0 D was high in both groups (≥ 95%) and only significantly better in the pIOL group between 1 and 6 months. (47) Both groups stability within 1.0 D results met or exceeded the FDA effectiveness target for stability for low and high myopia. (17;18;47)

Refractive Cylinder

The preoperative manifest cylinder was significantly higher in the LASIK group (LASIK, .88 ± .02 D; PIOL, .59 ± .05 D; P < .001); however, LASIK was more effective at reducing the cylinder. At all postoperative time points, the cylinder was significantly lower in the LASIK group. (47)

Best Spectacle Corrected Visual Acuity

While clinically significant losses of BSCVA (≥ 2 Snellen lines) were higher in the LASIK group than the pIOL group at all time points, the difference was only statistically significant at 1 week (P= .008). At 1 week, loss of BSCVA in the LASIK group was higher than the FDA safety value, but was less than 5% at all other time points for both groups. (47)

Clinically significant gains in BSCVA were significantly higher in the pIOL group than the LASIK group at all time points. (47)

Additional Refractive Surgeries

In the LASIK group, 416 eyes (25%) received additional LASIK re-treatments to enhance refractive correction. (47) None of the eyes in the pIOL group received LASIK procedures to enhance vision. (47)

Adverse Events

In the pIOL group, two pIOLs were replaced in the first week because they were too large and one pIOL was repositioned twice. In addition, one asymptomatic lens opacity [LOCS III anterior or posterior subcapsular opacity score ≥ to trace (1+) was observed]. (47)

In the LASIK group, 81 eyes (4.8%) developed diffuse lamellar keratitis. Striae in the corneal flap were observed in 30 eyes (1.8%), which were treated in 24 of these eyes by lifting the flap. One free cap (.06%) was observed, but this was not associated with any loss of BSCVA. (47)

Sanders, 2007 (40)

Sanders (40) also conducted a second case series that compared pIOLs and LASIK for eyes with moderate myopia (−3.0 to −7.88 D). This study is similar to the one described above and includes the same patients; however, the LASIK patients are a subset of the LASIK group (164 eyes) that was selected to match the pIOL group on age, gender, and spherical equivalent refraction. (40) The groups were well matched for age (P = .85), gender (P = .3), and mean preoperative MRSE (P =.79); however, the mean preoperative manifest cylinder was significantly higher in the LASIK group than the pIOL group (LASIK, .74 D; pIOL, .58 D; P= .037). (40)

Uncorrected Visual Acuity

The proportion of eyes achieving an UCVA of 20/20 or better was higher at all time points in the pIOL group than the LASIK group (this trend was significant at 1 and 6 months). (40) At all time points beyond 1 day, at least 90% of eyes achieved an UCVA of 20/40 or better in both groups. (40) Both groups exceeded the FDA effectiveness targets for UCVA for high and low myopia at all time points after 1 day.

Predictability of Manifest Refraction Spherical Equivalent

At all time points, predictability of MRSE within ± 0.5 and 1.0 D was higher in the pIOL group than the LASIK group, which reached significance at the 6 month time point. In the LASIK group, under-correction was common, especially in patients with higher myopia (< −6 D). (40) Both groups exceeded the low and high myopia FDA effectiveness targets for predictability within ± 0.5 and 1.0 D at all time points.

Stability of Manifest Refraction Spherical Equivalent

Stability of MRSE (change ≤ .5 D) was significantly higher in the pIOL group at all time points. Stability (change ≤ 1.0 D) was high in both groups (>92%), but significantly better in the pIOL group for the first month. (40) Stability within ± 1.0 D exceeded the high myopia FDA effectiveness target for stability after 1 month in the LASIK group and at all time points in the pIOL group.

Manifest Cylinder

The preoperative manifest cylinder was significantly higher in the LASIK group (LASIK, .74 ± .66 D, pIOL, .58 ± .56 D, P = .037). At all postoperative time points, however, the cylinder was significantly lower in the LASIK group compared with the pIOL group. (40)

Manifest Refraction Spherical Equivalent

There was no significant difference in the preoperative MRSE between the two groups (pIOL, −6.01 ± 1.40; LASIK, −6.01 ± 1.33; P = .794). While both groups achieved large decreases in MRSE, at 6 months postoperatively the MRSE was significantly lower in the pIOL group. (40)

Defocus Equivalent Refraction13

At 6 months, the proportion of eyes with defocus equivalent refraction less than or equal to 0.5, 1.0, or 2.0 D was higher in the LASIK group, but these differences were not significant. In both groups, 100% of eyes achieved a defocus equivalent refraction of less than or equal to 3.0 D. (40)

Best Spectacle Corrected Visual Acuity

Clinically significant losses of BSCVA were higher in the LASIK group at all time points and the difference was statistically significant at 1 week and 1 month, when the losses in the LASIK group exceeded the FDA safety targets. There were no significant differences between the LASIK and pIOL groups in terms of gains in two or more lines of BSCVA, which occurred in 2% to 4% of eyes in both groups at all time points. (40)

Additional Refractive Surgeries

In the LASIK group, 15 eyes (9.1%) received additional LASIK treatments to further enhance the refractive correction. The study protocol did not allow for patients in the pIOL group to receive enhancement procedures. (40)

Adverse Events

In the pIOL group, one lens (0.6%) was replaced during the first week postoperatively as it was too long, while another lens (0.6%) was repositioned twice due to improper placement in the eye. Seven eyes (3.7%) received additional YAG iridotomies, six to treat acute increases in intraocular pressure and one in an eye (0.6%) that did not receive the procedure preoperatively. (40)

In the LASIK group, 11 eyes (6.7%) developed diffuse lamellar keratitis and one of these eyes lost two lines of BSCVA. Striae in the corneal flap were observed in three eyes (1.8%) and were treated in two of these eyes by lifting the flap. Very thin flaps were observed in two eyes, while one eye had corneal ectasia. (40)

Limitations

An important limitation in this study is that despite matching the study groups on some variables, significant differences between the groups remained. The mean preoperative refractive cylinder was significantly higher in the LASIK group (cylinder: 0.74 D; range: 0.00 – 2.75 D) than the pIOL group (cylinder: 0.58 D; range: 0.00 – 2.50 D). The age limits for inclusion were also higher in the LASIK group (patients 21 to 50 years of age vs. 21 to 45 years of age) resulting in additional differences between the groups. (40)

High Myopia: Sanders and Vukich, 2003 (39)

Sanders et al. (39) conducted a case series that compared pIOLs with LASIK for high myopia (−8 to −12 D). The LASIK group consisted of 559 eyes from patients who had LASIK performed at the Davis Duehr Eye Center in Wisconsin between December 1998 and June 2001. The pIOL group consisted of 210 eyes from the US FDA Implantable Collamer Lens (STAAR Surgical Company) multicenter trial. The LASIK patients were significantly older (mean age: LASIK, 38.8 ± 9.41 years; pIOL, 36.3 ± 5.96 years; P= .001) and had lower myopia (mean preoperative MRSE: LASIK, −9.1 ± 0.97 D; pIOL, −9.8 ± 1.7 D; P < .001). (39)

Uncorrected Visual Acuity

The proportion of eyes that achieved an UCVA of 20/20 or better was significantly higher in the pIOL group at all time points. After 1 day, more than 80% of eyes in both groups achieved an UCVA of 20/40 or better. Both groups exceeded the FDA effectiveness target for UCVA for high myopia. (39)

Predictability of Manifest Refraction Spherical Equivalent

The proportion of eyes that achieved refraction within ± .5 D of emmetropia was significantly higher at all time points in the pIOL group. Similarly, after 1 week, the proportion of eyes that achieved refraction within ± 1.0 D of emmetropia was significantly higher at all time points in the pIOL group. (39) Both groups exceeded the low and high myopia FDA effectiveness targets for predictability within ± 0.5 and 1.0 D.

Stability of Manifest Refraction Spherical Equivalent

The stability of refraction was significantly higher in the pIOL group at all time points for changes of less than 0.5 D and 1.0 D. (39) The stability results within 1.0 D exceeded the low and high myopia FDA effectiveness targets for stability of MRSE at all time points in the pIOL group. The LASIK group, however, did not meet the FDA stability targets at any time point.

Best Spectacle Corrected Visual Acuity

Loss of two or more lines of BSCVA was significantly higher in the LASIK group at all time points except at 1 year. (39) At 1 week and 1 month, the LASIK group exceeded the FDA safety target for loss of BSCVA. The proportion of eyes that gained two or more lines of BSCVA was higher in the pIOL group at all time points, and significantly higher at the 1 week and 6 months. (39)

Additional Refractive Surgeries

Eleven eyes (5.2%) in the pIOL group underwent additional refractive surgeries (LASIK or PRK) after pIOL implantation. In the LASIK group, 128 eyes (23%) were received additional LASIK treatments to enhance refractive correction. (39)

Adverse Events

Few adverse events were observed in either group. In the pIOL group, one lens was repositioned at 2 weeks. No clinically significant lens opacities or other adverse events were observed. (39) In the LASIK group, 17 eyes (3%) developed diffuse lamellar keratitis and striae in the corneal flap were observed in 17 eyes and were treated in 12 of these eyes. A single free cap (0.2%) was also observed but not associated with any loss of BSCVA. (39)

Limitations

While patient follow-up was high in the pIOL group (88% at 1 year), it was much lower in the LASIK group (18% at 1 year). (39) Unlike the pIOL group, patients in the LASIK group were not enrolled in a clinical trial and were assessed at routine follow-up visits, which patients frequently missed. The 6 month follow-up for the LASIK group was also actually a combination of the 3, 6, and 9 month follow-up visits (if a patient attended more than one of these visits, the later visit was chosen). (39) Based on comparisons of early postoperative visits, patients lost to follow-up were not significantly different than those who were followed for the entire study with regards to changes in BSCVA, UCVA, and predictability. (39)

Phakic Intraocular Lenses Compared with LASIK for Myopic Astigmatism

Table 34 provides a summary of the 1 week, 1 month, 6 months, and 12 months postoperative results from the studies which compared pIOLs with LASIK for myopic astigmatism.

Table 34:
Summary of Outcomes from the Studies Comparing pIOLs with LASIK for Myopic Astigmatism

Kamiya et al. 2008 (49)

Kamiya et al. (49) conducted a case series that compared pIOLs with wavefront-guided LASIK. Patient recruitment and inclusion criteria for each group were not described in the paper. Patients in the pIOL group had significantly higher myopia (preoperative mean MRSE: pIOL, −10.8 ± 2.4 D, LASIK, −7.9 ± 1.5 D, P< .001) and refractive cylinder (preoperative mean cylinder: pIOL, 2.1 ± 0.8 D, LASIK, 1.3 ± 0.4 D, P< .001), and significantly worse preoperative UCVA (logMAR UCVA: pIOL, 1.55 ± 0.14, LASIK, 1.43 ± 0.24, P= .004).

Uncorrected Visual Acuity

The proportion of eyes that achieved an UCVA of 20/20 or better was higher in the pIOL group at all time points. Uncorrected visual acuity of 20/40 or better was not reported by the study, but the proportion of eyes seeing 20/20 or better uncorrected exceeded the FDA targets for UCVA of 20/40. (49)

Efficacy Index

The efficacy index at 6 months was higher in the pIOL group than the LASIK group (pIOL, 0.87 ± 0.15, LASIK, 0.83 ± 0.23). (49)

Predictability of Manifest Refraction Spherical Equivalent

The proportion of eyes that achieved refraction within ± 0.5 of emmetropia was higher in the pIOL group at all time points. Similarly, the proportion of eyes within ± 1.0 D of targeted refraction was higher in the pIOL group at all times, but the differences between the 2 groups were much smaller. (49) Both the pIOL and LASIK groups meet the low and high myopic astigmatism FDA effectiveness targets for predictability within 0.5 and 1.0 D at all time points.

Manifest Refraction Spherical Equivalent

The MRSE was substantially reduced in both groups at all postoperative follow-up visits. At 1 week, 1 month, and 3 months, the pIOL group was lower (closer to emmetropia) than the LASIK group. At 6 months, however, the LASIK group was closer to emmetropia than the pIOL group. (49)

Stability of Manifest Refraction Spherical Equivalent

Stability of refraction was higher in the pIOL group: the mean change in MRSE from 1 week to 6 months was −0.04 ± .24 D and −0.60 ± 0.49 D in the pIOL and LASIK groups, respectively. (49)

Refractive Cylinder

The postoperative cylinder was lower at all time points in the LASIK group. (49)

The predictability of refractive cylinder correction was higher in the LASIK group at most follow-up visits. The proportion of eyes within ± 0.5 D of the attempted cylinder correction was higher in the LASIK group at almost all time points. The same trend was observed within ± 1.0 D, but the differences between the predictability of the LASIK and pIOL corrections were smaller. (49)

Best Spectacle Corrected Visual Acuity

A clinically significant loss of two or more lines of BSCVA was not observed in either group. Compared with the LASIK group, more eyes in the pIOL group gained two or more lines of BSCVA (LASIK, 4%, pIOL, 13%). (49) The FDA safety target for loss of BSCVA was not exceeded in either group.

Safety Index

The safety index at 6 months was higher in the pIOL group than the LASIK group (pIOL, 1.28 ± .25, LASIK, 1.01 ± 0.16). (49)

Additional Refractive Surgeries

Two eyes (8.3%) in the LASIK group received an additional LASIK treatment to enhance the refractive correction. No eyes in the pIOL group received additional refractive surgeries (49)

Adverse Events

No adverse events were observed in either group. (49)

Limitations

Except for the demographic characteristics, P values were not reported in this paper, so the statistical significance of the results is unknown. In addition, the paper reported only a limited description of participant recruitment and inclusion criteria and no description of loss to follow-up.

Sanders and Sanders, 2008 (50)

Sanders and Sanders (50) conducted a case series comparing pIOLs and custom ablation LASIK for the treatment of myopic astigmatism. The pIOL group consisted of 210 eyes from 124 patients that participated in the US FDA multicenter clinical trial of the Toric Implantable Collamer Lens (STAAR Surgical Company). The LASIK data was derived from published Safety and Effectiveness Summaries of the approved Premarket Approval Applications (obtained from the FDA through the Freedom of Information Act) for the VISX CustomVue and Alcon CustomCornea laser systems. (50) Results were compared for patients with moderate (−3 to −7 D) and high (−7 to −11 D) myopia.

Uncorrected Visual Acuity

In the moderate myopia comparison, while more eyes achieved an UCVA of 20/20 or better in the pIOL group, there were no significant differences between the three groups (P= .109). Similarly, there were no significant differences in the high myopia groups (P= 1.00). (50)

Most eyes (≥ 94% in each group) achieved an UCVA of 20/40 or better, and the proportions were not significantly different between groups. (50) Both the moderate and high myopia groups for LASIK and pIOLs met the FDA effectiveness targets for UCVA of 20/40.

Predictability

While the proportion of eyes that were corrected within ± 0.5 D of emmetropia was slightly higher in the pIOL group for both moderate and high myopia eyes, there was no significant difference between the groups. Predictability within ± 1.0 D was high in all groups (> 82%) and there was no significant difference between the groups with moderate myopia. For the high myopia group, however, predictability was significantly higher in the pIOL group than the Alcon CustomCornea (97% vs. 82%, P= .008), but not the VISX CustomVue (97% vs. 91%, P = .094). (50) All groups met or exceeded the low and high FDA effectiveness targets for predictability within ± 0.5 and 1.0 D.

Best Spectacle Corrected Visual Acuity

Loss of two or more lines of BSCVA was not reported in the study. The proportion of eyes that gained two or more lines of BSCVA was higher in the pIOL group: 20% in the pIOL group versus 11% in the VISX CustomVue group and 2% in the Alcon CustomCornea group. (50)

Additional Refractive Surgeries and Adverse Events

Additional refractive surgeries and adverse events were not reported in this paper. (50)

Limitations

The LASIK data reported in this study was based on published Safety and Effectiveness Summaries of the approved Premarket Approval Applications for the two laser systems. Like many secondary data sources, the published result summaries did not provide complete information for all outcomes that were examined in this study. In addition, the LASIK data could not be combined into a single comparison group. (50)

Phakic Intraocular Lenses Compared with Photorefractive Keratectomy for Myopic Astigmatism

Table 35 provides a summary of the 1 week, 1 month, 6 months, and 12 months postoperative results from the studies that compared pIOLs with PRK for myopic astigmatism.

Table 35:
Summary of Outcomes from Schallhorn et al. Comparing pIOLs with Photorefractive Keratectomy for Myopic Astigmatism

Schallhorn et al., 2007 (8)

Schallhorn et al. (8) conducted an RCT to compare pIOLs with PRK for the treatment of myopic astigmatism. Patients with moderate to high myopia, astigmatism between 1.0 and 4.0 D cylinder, and BSCVA of 20/40 or better were enrolled in the study. Patients were randomized to receive either the Visian toric implantable collamer lens (STAAR Surgical) or conventional PRK14 using the VISX Star S3 (VISX Inc, Santa Clara, California) excimer laser combined with mitomycin C15. The pIOL and PRK groups were similar with respect to age, gender, preoperative mean MRSE, and preoperative mean cylinder. (8)

Uncorrected Visual Acuity

The proportion of eyes that achieved an UCVA of 20/20 or better was higher in the pIOL group compared with the PRK group at all time points. This difference was significant at 1 week and 12 months. Uncorrected visual acuity improvements occurred faster in patients who received pIOLs than PRK as evidenced by the significant different at 1 week. Similarly, the proportion of eyes with UCVA 20/12.5 or better and 20/16 or better was significantly higher in the pIOL group at all time points (UCVA ≥ 20/12.5, P ≤ .001; UCVA ≥ 20/16, P < 0.005). (8)

Uncorrected visual acuity of 20/40 or better was not reported by in study, but the proportion of eyes seeing 20/20 or better uncorrected exceeded the FDA targets for UCVA of 20/40.

Predictability of Manifest Refraction Spherical Equivalent

The percentage of eyes that achieved refraction within ± 0.5 D of emmetropia was significantly higher in the pIOL group for all time points except at 12 months (P<.019). Predictability within ± 1.0 D was significantly higher in the pIOL group at all time points (P< .003), ranging from 98% to 100% of eyes in the pIOL group versus 55% to 80% in the PRK group. In the pIOL group, refraction within ± 0.5 and 1.0 D of emmetropia was achieved within the first week after surgery and remained relatively stable over the 1 year follow-up; more variation was observed over time in the PRK group. (8) The pIOL group exceeded the low and high FDA effectiveness targets for predictability within ± 0.5 and 1.0 D at all time points. The PRK group exceeded the FDA target for high myopia at most time points, but not for low myopia.

Stability of Manifest Refraction Spherical Equivalent

The stability of refraction (proportion of eyes with ≤ 0.5 D change) was significantly better in the pIOL group for the first 6 months (P < .03); however, in the last six months, the stability was high in both groups. Similarly, the stability within 1.0 D was significantly higher in the pIOL group in the first 6 months (P< .028), but was high in both groups in the final 6 months. (8) The high myopia FDA effectiveness target for stability of MRSE within 1.0 D was exceeded at all time points in the pIOL group, but the PRK group did not meet the target at any time point.

Refractive Cylinder

The refractive cylinder was lower in the pIOL group at 1 week, 1 month, and 3 months, but the difference was only significant at 1 week. At 6 months and 1 year, the refractive cylinder was lower in the PRK group, but these differences were not significant. Stability of manifest cylinder was high in both groups, but the pIOL group achieved significantly better stability in the first few postoperative months. (8)

Manifest Refraction Spherical Equivalent

The MRSE was lower (closer to emmetropia) in the pIOL group at all postoperative time points, and significantly lower from 1 week to 6 months. (8)

Best Spectacle Corrected Visual Acuity

The preoperative mean BSCVA was similar in the pIOL and PRK groups (−0.04 ± 0.09 and −0.04 ± 0.12, respectively). (8) The postoperative mean BSCVA and mean line change were significantly higher in the pIOL group at all follow-up points (P < .001 for both outcomes).

Clinically significant losses of BSCVA were observed in the PRK group in the first month after surgery but this declined over time: 19% of eyes at 1 week, 4% at 1 month, and 0% after. The PRK group exceeded the FDA targets for loss of BSCVA at 1 week and 1 month. No eyes lost two or more lines of BSCVA after pIOL implantation. (8) One eye in the PRK group and four to six eyes in the pIOL group gained two or more Snellen lines; however, the increases in BSCVA disappeared after 3 months.

Adverse Events

At 1 month, a visually insignificant anterior lens opacity was observed in one eye in the pIOL group, which was not associated with a significant loss of BSCVA or UCVA. (8) A grade 2 anterior subcapsular cataract was observed in one pIOL patient at 2 years postoperatively. The patient required pIOL removal and cataract extraction, after which, BSCVA was restored to 20/20. No other adverse events were reported. (8)

Quality of Vision

Compared with the pIOL group, 3 to 6 months after surgery, patients in the PRK group experienced significantly more vision fluctuation (P = .001), glare symptoms at night (P= .033), glare from oncoming car headlights at night (P = .014), and problems with dry eyes (increased need for artificial tears) (P= .002). At 12 months, problems with dry eyes were the only visual symptom that remained significantly different between groups. (8)

Limitations

The quality of this study was assessed using the Jadad scale which evaluates RCTs based on randomization, blinding, and follow-up. (51) Schallhorn et al. (8) scored 1 out of a possible 5 points and is therefore low quality.

Phakic Intraocular Lenses Compared with Clear Lens Extraction for Myopia

Table 36 provides a summary of the 1 week, 1 month, 6 months, and 12 months postoperative results from the studies that compared pIOLs with CLE for myopia.

Table 36:
Summary of Outcomes from Arne et al. Comparing pIOL with Clear Lens Extraction for Myopia

Arne, 2004 (48)

Arne (48) conducted a case series comparison of pIOLs with CLE for high myopia. The pIOL group consisted of 41 eyes from 21 patients who received an implantable collamer lens (STAAR Surgical Company). The CLE group was 36 eyes from 18 patients who received phacoemulsification of the crystalline lens and implantation of an AcrySof posterior chamber IOL (Alcon). Patients were allocated based on different enrolment criteria such as recent changes in distance visual acuity, opacification of the crystalline lens, and anterior chamber depth. Emmetropia was the target refraction for the pIOL group, while −2 D was the target for the CLE group.

Predictability

Predictability of MRSE within ± 1.0 and 2.0 D of target refraction was higher in the pIOL group. In the pIOL group, 71% of eyes (29/40) achieved a MRSE within ± 1.0 D of emmetropia and 83% (34/41) within ± 2.0 D. In the CLE extraction group, −2 D was the residual refraction target rather than emmetropia with 47% of eyes (17/36) being within ± 1.0 D of this target and 81% (29/41) within ± 2.0 D. (48) Neither group met the high myopia FDA effectiveness target for predictability within 2.0 D. While the CLE group also did not meet the 1.0 D predictability target, the pIOL group exceeded this target.

Manifest Refraction Spherical Equivalent

Compared with the CLE group, mean postoperative MRSE was closer to emmetropia in the pIOL group.

Best Spectacle Corrected Visual Acuity

Preoperatively, 76% (31/41) of eyes had a BSCVA of 20/40 or better in the pIOL group and 58% (21/36) in the CLE group. This increased in both groups to 88% of eyes in the pIOL group and 81% in the CLE group. There were no clinically significant losses of BSCVA in the pIOL group, but at least two eyes in the CLE group lost two or more lines of BSCVA after retinal detachments. (48)

Additional Refractive Surgeries

No additional refractive surgeries to improve vision were reported in the paper.

Adverse Events

In the pIOL group, three eyes developed lens opacification, which were treated by lens removal and cataract extraction. Inadequate vaulting leading to contact between the lens and the anterior capsule was observed in one of the cataract cases. Visual acuity after phacoemulsification was good: 6 months after cataract removal, all eyes achieved a BSCVA of 20/32 or better. At 2 years, one eye experienced an increase in intraocular pressure, which was well controlled with topical beta-blockers. (48)

In the CLE group, 17 eyes (47.2%) developed posterior capsule opacifications requiring neodymium:YAG capsulotomy, 12 in the first postoperative year and five in years 2 to 4. Retinal detachment occurred in two eyes (5.55%) at 39 and 43 months and re-attachment was unsuccessful in one eye. After detachment, BSCVA was low in both eyes (counting fingers and 20/200, respectively). (48)

Endothelial Cell Loss

The rate of endothelial cell loss was equivalent in both groups16 (pIOL, 2.0%; CLE, 1.9%). (48)

Satisfaction

As shown in Table 37, satisfaction was higher in the pIOL group.17 In addition, 7 patients in the CLE group were unsatisfied with their near vision which required spectacle correction post-surgery. (48)

Table 37:
Satisfaction with Results

Limitations

A major limitation to this study was that the enrolment criteria for the pIOL and CLE groups were different, so the resulting study groups were not well matched (e.g. the CLE group was significantly older than the pIOL group, P = .05). Thus, differences in outcomes between the groups could be due to preoperative group differences.

Many important outcomes such as UCVA, stability of refraction, and loss of BSCVA were not reported in this paper. As well, the actual complication rate for posterior capsule opacification was difficult to determine because different numbers reported in the paper (47.2% and 41.7%). (48)

Long-term follow-up was limited with loss to follow-up exceeding 20% in both groups after 2 years (all eyes were followed for 2 years). In the pIOL group, 51% of eyes were followed for 4 years and 64% in the CLE group. Reasons for dropouts and withdrawals were not provided.

General Limitations: Comparative Studies

Several limitations applied to most or all of the studies (summarized below and in Table 38). In all seven studies, most of the patients received treatment (pIOL, LASIK, PRK, or CLE) for both eyes and the number of eyes was used as the unit of analysis. As described in the General Limitations section for the efficacy studies, measurements from two eyes of the same individual are correlated (within-subject correlation), which violates the assumption of independent data units on which most standard statistical significance tests are based. Thus, the variability of the data is decreased and the statistical power of the study is increased, which may result in falsely precise confidence intervals and small P values. (44-46) None of the studies attempted to correct for within-subject correlations (e.g. analyze data from one eye only or use statistical techniques to correct for correlation). Thus, the reported results may be falsely precise and some of the observed statistically significant results may be spurious.

Table 38:
Summary of Major Limitations in the Comparative Studies

Selection bias was also a problem. In five of the studies, the patient groups were not well matched with significant differences between the patient populations in regards to important population characteristics such as mean preoperative MRSE, UCVA, age, and refractive cylinder. Furthermore, in Arne (48), the inclusion criteria for the two study groups differed. As these variables were usually worse in the pIOL group (i.e., higher preoperative myopia), the data is probably biased in favour of the LASIK, so the observed benefit of pIOLs may be an underestimate. (39;47-49)

The high attrition rates in the LASIK groups compared to the pIOL groups may also be a source of selection bias. For instance, in Sanders and Vukich, 2006 (47), the LASIK group lost about 30% of patients at 1 week, 1 month, and 6 months. In Sanders and Vukich, 2003, the loss to follow-up in the LASIK group was 31% at 6 months and more than 80% at 1 year.

A major reason for higher loss to follow-up in the refractive surgery group compared with the pIOL group is that in most of these studies, the pIOL data was obtained from eyes participating in U.S. FDA clinical trials while the LASIK data was obtained from routine clinical follow-up of patients receiving refractive surgery. In clinical trials, testing procedures and data collection are based on strictly standardized protocols that often lead to more complete, reliable, and precise data. In clinical trials, for example, investigators must ensure patients read the maximum lines of UCVA or BSCVA, but this may not occur in routine clinically follow-up. (40)

In most of the studies, patients in the LASIK groups were allowed to undergo additional refractive surgery procedures to further enhance refractive correction. In one study, patients in the pIOL group were also allowed to receive LASIK or PRK treatments after pIOL insertion. The reported refractive results include the results after the additional corrections, which could bias the results because the vision changes resulting from these enhancement procedures will make the procedure appear more effective.

Another important consideration is that refractive surgery techniques have evolved over time and are becoming increasingly accurate and precise. These comparisons may thus overestimate the benefit of pIOLs compared with LASIK/PRK.

Finally, an important limitation for most of these studies is the study design itself, comparative case series, which downgrades the evidence based on the GRADE Working Group Criteria. The GRADE quality of the evidence is discussed in more depth at the end of this section.

Discussion

Overall, pIOLs performed better than LASIK, PRK, or CLE for many of the examined outcomes. The proportion of eyes that achieved an UCVA of 20/20 or better was higher in the pIOL group compared with the LASIK and PRK18 groups at all time points, this difference was significant at many time points. (8;39;40;47;49;50) In the studies that reported MRSE, the postoperative result was lower (closer to emmetropia) in the pIOL groups compared with the refractive surgery groups.(8;40)

Predictability within ± 0.5 and ± 1.0 D of emmetropia was higher in the pIOL group compared with the refractive surgery groups (LASIK, PRK, or CLE) in all of the studies, a difference that was often statistically significant. (8;39;40;47-50) This trend was consistent despite higher residual astigmatism in the pIOL group (since LASIK can treat astigmatism, but non-toric pIOLs cannot) and additional refractive enhancement treatments in many eyes in the refractive surgery groups. The decreased predictability of refractive surgery in the LASIK and PRK groups is likely the result of the difficultly associated with accurately ablating tissue that is subject to healing, compared with a lens that is manufactured for an exact correction. (39;40;47)

In addition, stability of manifest refraction (changes ≤ 0.5 and 1.0 D between time points) was higher, an often significantly higher, in the pIOL group compared with the LASIK and PRK groups19 at all postoperative time points. (8;39;40;47;49) The reduced stability after LASIK and PRK may be due to the time it takes for corneal tissue to heal, which can affect refraction. In contrast, the pIOLs used in these studies (posterior chamber foldable lenses) require only a 3 mm clear corneal incision, similar to that used in cataract surgery, which has been shown to have minimal effect on refraction. (39;40;47;50)

The proportion of eyes that gained of two or more lines of BSCVA was higher in the pIOL groups than the refractive surgery groups. (8;39;47;49;50) These clinically significant gains in BSCVA in the pIOL group have been attributed to increased magnification. It is thought that patients treated with LASIK do not achieve similar gains in BSCVA because of increased higher order aberrations that degrade retinal images. (9;41;42;51;52)

Compared with the pIOL group, loss of two or more lines of BSCVA (an important safety concern) was much more common in the LASIK, PRK, and CLE groups, especially early on in the healing process (i.e. within the first postoperative month); however, almost all of the reported losses were within the FDA safety targets (loss of ≥ 2 lines of BSCVA in < 5% of eyes).

The only outcome that favoured refractive surgery (LASIK and PRK) over pIOLs was correction of refractive cylinder. In the three studies that reported this outcome, LASIK was more effective at reducing astigmatism than pIOLs at most time points. (9;42;50) Similarly, predictability within ± 0.5 and 1.0 D of targeted refractive cylinder was higher in the LASIK group. (50) While this is result is understandable in the myopic eye populations (as non-toric pIOLs cannot correct astigmatism while LASIK and PRK can), this trend remained true in the comparison between LASIK and toric pIOLs for the treatment of myopic astigmatism. (50)

Finally, the long-term effectiveness and safety of pIOLs compared with refractive surgery is unknown. The identified studies provided only 6 to 12 months of follow-up data and these short-term results were further hampered by high loss to follow-up.

GRADE Quality of the Evidence: Comparative Studies

A summary of the GRADE quality of evidence for each comparison and refractive error is provided in Table 39. Due to serious limitations in study quality, issues with directness, and sparse data (details in Appendix 3), the evidentiary value of the literature comparing pIOLs with refractive surgeries was determined to be of low or very low quality.

Table 39:
Summary of GRADE Quality of Evidence

Phakic Intraocular Lenses for Low Vision

Experts in low vision were contacted to discuss the utility of pIOLs in patients with low vision. Low vision cannot be corrected by pIOLs as it is usually the result of more than just a severe refractive error. Implantation of a pIOL in a patient with low vision and myopia would eliminate the eye’s natural ability to magnify near objects and make the patient reliant on external magnifiers. For patients with low vision and hyperopia, a pIOL could provide magnification for near vision, but as this can be achieved with plus lenses in head-borne, hand-held, or electronic devices, pIOLs are not recommended for these patients. This is level 5 evidence based on expert opinion.

Summary of Findings

Pre-Post Case Series

Based on the GRADE Working Group Criteria (52), the quality of evidence ranged from low to very low, depending on the outcome, so any estimate of effect is uncertain (as summarized in Table 40).

Table 40:
Summary of Findings from the Pre-Post Case Series

Comparative Studies

Overall, for most outcomes, the results favoured pIOLs compared with LASIK, PRK, and CLE for the treatment of moderate to high myopia and myopic astigmatism (Table 41). However, LASIK, PRK, and CLE result in superior correction of refractive cylinder (astigmatism) compared to both toric and non-toric pIOLs20. Based on the GRADE Working Group Criteria (52), the quality of evidence is low to very low, so any estimate of effect is uncertain.

Table 41:
Summary of Findings from the Comparison of pIOLs with LASIK for Myopia and Myopic Astigmatism

Conclusions

  • While pIOLs improve UCVA with high predictability, stability, and patient satisfaction for low to high refractive errors, there is no clinical advantage to using a pIOL as opposed to alternative corrective options.
  • Adverse events are a potential concern.
  • pIOL use in low vision has not been explored because low vision is caused by a comorbid condition (e.g. macular degeneration) that cannot be corrected by a pIOL.

Diffusion of pIOL

Diffusion in Ontario

Correction of low to high refractive errors is not insured in Ontario. The Ministry of Health and Long-Term Care Assistive Devices Program does, however, cover specialized glasses and lenses for anyone with long-term low vision or blindness that cannot be corrected medically, surgically or with ordinary eyeglasses or contact lenses (e.g. corrected vision in the better eye is in the range of 20/70 or less). (3)

Clear lens extraction is covered by OHIP for people who have vision loss due to a disease of the lens, but refractive errors are not considered a disease of the lens in this policy (Box 1).

Box 1.

Ontario Health Insurance Payment Policy for clear lens extraction.

It is recommended that clear lens extraction followed by IOL insertion be eligible for payment under OHIP when the patient has:

  1. Best corrected vision of worse than 20/40,
  2. Visual loss is due to a disease of the lens, and
  3. Does not have coexistent conditions, such as amblyopia, which would render the surgery ineffective.

Note: In this context refractive errors are not to be considered a disease of the lens.

The claims should be submitted to the Ministry for prior-approval and paid under R990 at a fee equal to E140 and E950. Information required to assess the prior approval request includes a description of the lens disease, test results and current visual acuity. Where available, previous measurements of visual acuity (to try to demonstrate amblyopia does not exist) should be sought out and reviewed.

Diffusion in Other Provinces

As of March 2008, pIOLs were not insured by other provinces and territories in Canada (Table 42).

Table 42:
Status of Phakic Intraocular Lenses in Canadian Provinces/Territories

Diffusion Outside Canada

United States

Visual impairment due to myopia, hyperopia, and astigmatism can be corrected by external contact lenses and eyeglasses, so refractive keratoplasty, and specifically phakic intraocular lenses, for the treatment of refractive errors is not considered medically necessary. Therefore, most of the major insurers in the United States including CIGNA, Aetna, Blue Cross Blue Shield, Excellus Health Plan Inc, and Centers for Medicare and Medicaid Services do not cover phakic intraocular lenses or other refractive keratoplasty procedures. (53-57)

United Kingdom

The National Institute for Health and Clinical Excellence issued the following guidance about pIOLs for refractive errors in February 2009:

Current evidence on intraocular lens (IOL) insertion for correction of refractive error, with preservation of the natural lens is available for large numbers of patients. There is good evidence of short-term safety and efficacy. However, there is an increased risk of cataract, corneal damage or retinal detachment and there are no long-term data about this. Therefore, the procedure may be used with normal arrangements for clinical governance and audit, but with special arrangements for consent.

Clinicians wishing to undertake IOL insertion for correction of refractive error, with preservation of the natural lens should ensure that patients understand the risks of having an artificial lens implanted for visual impairment that might otherwise be corrected using spectacles or contact lenses. They should understand the possibility of cataract, corneal damage or retinal detachment, and the lack of evidence relating to long-term outcomes. Patients should be provided with clear information. In addition, the use of NICE’s information for patients (‘Understanding NICE guidance’) is recommended (available from www.nice.org.uk/IPG289publicinfo).

Both clinicians and manufacturers are encouraged to collect long-term data on people who undergo IOL insertion, and to publish their findings. NICE may review the procedure on publication of further evidence. (21)

Economic Analysis

Disclaimer: The Medical Advisory Secretariat uses a standardized costing methodology for all of its economic analyses of technologies. The main cost categories and the associated methods from the province’s perspective are as follows:

Hospital: Ontario Case Costing Initiative cost data are used for all in-hospital stay costs for the designated International Classification of Diseases-10 (ICD-10) diagnosis codes and Canadian Classification of Health Interventions procedure codes. Adjustments may need to be made to ensure the relevant case mix group is reflective of the diagnosis and procedures under consideration. Due to the difficulties of estimating indirect costs in hospitals associated with a particular diagnosis or procedure, the secretariat normally defaults to considering direct treatment costs only.

Nonhospital: These include physician services costs obtained from the Ontario Schedule of Benefits for physician fees, laboratory fees from the Ontario Laboratory Schedule of Fees, device costs from the perspective of local health care institutions, and drug costs from the Ontario Drug Benefit formulary list price.

Discounting: For all cost-effectiveness analyses, a discount rate of 5% is used as per the Canadian Agency for Drugs and Technologies in Health.

Downstream costs: All costs reported are based on assumptions of utilization, care patterns, funding, and other factors. These may or may not be realized by the system or individual institutions and are often based on evidence from the medical literature. In cases where a deviation from this standard is used, an explanation has been given as to the reasons, the assumptions, and the revised approach. The economic analysis represents an estimate only, based on assumptions and costing methods that have been explicitly stated above. These estimates will change if different assumptions and costing methods are applied for the purpose of developing implementation plans for the technology.

Literature Review

A literature review was conducted and no cost-effectiveness (cost-utility) economic analysis on the use of pIOL for refractive errors was identified.

Hospital, Physician and Device Costs of Phakic IOLs

Current clinical guidelines from the Canadian Ophthalmological Society for usual care of refractive errors were used to estimate pre-operative, surgical and post-operative costs associated with pIOL implantation. (58) Hospital and physician costs associated with the current standard of care were estimated using average patient costs from the Ontario Case Costing Initiative, and physician fees from the schedule of medical benefits for health professionals from the Ontario Ministry of Health and Long-Term Care and Alberta Health and Wellness. (59-61)

Hospital day surgery and physician costs and the corresponding procedure and fee codes used in the current analysis are listed in Table 43. As pIOL implantation is not covered by the Ontario Health Insurance Schedule of Benefits, physician costs for surgery were estimated from the fee code E146, associated with the secondary insertion of an intraocular lens prosthesis after cataract removal. (59) Similarly, as pIOL procedures are not publically insured in Ontario, hospital surgery costs are based on 2009 CCI codes for lens implantation (1.CL.53) for ICD-10-CA codes related to myopia (H521). (60;61) Also note the cost of the phakic lens is non-specific to astigmatism, myopia, or hyperopia and represents the average cost of the different lens as determined through consultations with phakic intraocular lens manufacturers. “Physician” and “Device” surgery costs in Table 43 are listed for refractive error correction of one eye only and were multiplied by two to estimate the average cost per patient.

Table 43:
Physician, Hospital and Device costs for Phakic IOL Implantation by Stage of Care

Cases of Refractive Error in Ontario

The prevalence of refractive errors differs by age group and type of error. The number of cases of astigmatism, myopia and hyperopia for people of age 20-59 was estimated by Vitale et al. in 2008. (1) In the United States, the prevalence of refractive errors for people aged 20-39 and 40-59 was approximately:

  • 23.1% and 27.6% for astigmatism (≥ 1D cylinder),
  • 7.4% and 7.8% for myopia (≤ -5D), and
  • 1.0% and 2.4% for hyperopia (≥ 3 D).

In Ontario, these rates of refractive errors imply approximately 1.76 million cases of astigmatism, 520,000 cases of myopia, and 120,000 cases of hyperopia in 2006. The total number of cases of refractive errors is estimated as being 2.40 million.

Estimated Costs for Ontario

To estimate the cost of pIOL implantation for refractive errors in Ontario, the summarized costs were taken to represent the anticipated average cost per case for each stage of care. The total average hospital, physician and device costs were estimated as being $4,200 per case, with stage-specific average costs of approximately $106 for pre-operative ophthalmic testing, $1,477 for surgery and $58 for post-operative care. The total number of cases of refractive errors in Ontario was used to calculate an approximate cost of $10 billion. The cost estimation represents the maximum possible cost to Ontario taking a Ministry of Health perspective to insure pIOL implantation procedures for refractive errors. Limitations of this estimate include: every case of refractive error has a pIOL implant, the physician cost of the pIOL procedure is estimated from current IOL lens removal and replacement fees (after cataract removal), and the prevalence of refractive errors in the United States was used to represent that found in Ontario.

Appendices

Appendix 1: Search Strategy

Search date: January 30, 2009

Databases searched: MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, Cochrane

Library (all via OVID); CRD/INAHTA

 

Ovid MEDLINE(R) <1996 to January Week 3 2009>

Search Strategy:

  1. exp Vision, Low/ (981)
  2. (vision adj2 (low or loss or impaired or reduc* or diminished or sub?normal)).ti,ab. (4168)
  3. exp Refractive Errors/ (10007)
  4. exp Astigmatism/ (2327)
  5. (ametropic or ametropia$ or myopia$ or myopic or astigmatism or hyperopia$ or hyperopic or hypermetropia$ or far?sighted$ or near?sighted$ or long?sighted$ or short?sighted$ or refractive error$).ti,ab. (9944)
  6. or/1-5 (17100)
  7. exp Lens Implantation, Intraocular/ or exp Lenses, Intraocular/ (7114)
  8. (phakic or piol* or p-iol*).mp. [mp=title, original title, abstract, name of substance word, subject heading word] (992)
  9. (toric or Artisan or Verisyse or Visian or STAAR or AcrySof).mp. [mp=title, original title, abstract, name of substance word, subject heading word] (843)
  10. ((implant* or intraocular) adj2 lens*).mp. (7878)
  11. (collamer adj2 lens*).mp. (31)
  12. (iol or iols).mp. [mp=title, original title, abstract, name of substance word, subject heading word] (3550)
  13. or/7-12 (8672)
  14. 6 and 13 (2040)
  15. limit 14 to (english language and humans and yr=“2003 - 2009”) (927)
  16. limit 15 to (case reports or comment or editorial or letter) (241)
  17. 15 not 16 (686)

 

Embase: EMBASE <1980 to 2009 Week 04>

Search Strategy:

  1. exp Refraction Error/ or exp Astigmatism/ (17319)
  2. (vision adj2 (low or loss or impaired or reduc* or diminished or sub?normal)).ti,ab. (5898)
  3. (ametropic or ametropia$ or myopia$ or myopic or astigmatism or hyperopia$ or hyperopic or hypermetropia$ or far?sighted$ or near?sighted$ or long?sighted$ or short?sighted$ or refractive error$).ti,ab. (13770)
  4. or/1-3 (25097)
  5. exp lens implant/ (9953)
  6. exp Lens Implantation/ (2296)
  7. (phakic or piol* or p-iol*).mp. [mp=title, abstract, subject headings, heading word, drug trade name, original title, device manufacturer, drug manufacturer name] (1454)
  8. (toric or Artisan or Verisyse or Visian or STAAR or AcrySof).mp. [mp=title, abstract, subject headings, heading word, drug trade name, original title, device manufacturer, drug manufacturer name] (1013)
  9. ((implant* or intraocular) adj2 lens*).mp. [mp=title, abstract, subject headings, heading word, drug trade name, original title, device manufacturer, drug manufacturer name] (12937)
  10. (collamer adj2 lens*).mp. [mp=title, abstract, subject headings, heading word, drug trade name, original title, device manufacturer, drug manufacturer name] (32)
  11. (iol or iols).mp. [mp=title, abstract, subject headings, heading word, drug trade name, original title, device manufacturer, drug manufacturer name] (4790)
  12. or/5-11 (14281)
  13. 4 and 12 (2771)
  14. limit 13 to (human and english language and yr=“2003 - 2009”) (1001)
  15. limit 14 to (editorial or letter or note) (165)
  16. Case Report/ (1022358)
  17. 14 not (15 or 16) (669)

Appendix 2: Results from Guell et al. (27)

Guell et al. (27) conducted a retrospective case series of 399 eyes with myopia, hyperopia, or astigmatism. Results were reported for four groups:

  • Group 1, myopia eyes that received lens model 204 (n = 101),
  • Group 2, myopic eyes that received lens model 206 (n = 173),
  • Group 3, hyperopic eyes that received lens model 203 (n = 41), and
  • Group 4, astigmatic eyes that received the toric lens model (n = 84). (27)

Table 1 in Appendix 4 provides a summary of the results from this study for the first three groups. Since the toric model is not licensed by Health Canada, this study group was excluded from the reported results. When possible, results for the two myopic eye groups were combined.

UCVA

At the 3 month follow-up, an UCVA of 20/20 or better was achieved in 1.8% of myopic eyes and 0% of hyperopic eyes. An UCVA of 20/40 or better was achieved in 32.5% and 41.6% of myopic and hyperopic eyes, respectively. (27) These results are very low compared to the FDA target for UCVA of 20/40 (75% of high myopes and 85% of low myopes). (27)

Predictability

At 3 months, 27.4% and 63.4% of myopic eyes achieved a MRSE within ± 0.5 D and 1.0 D of emmetropia, respectively. These results do not meet the FDA targets for predictability (30% of high myopes and 50% of low myopes within ± 0.5 D of emmetropia and 75% of high myopes and 85% of low myopes within ± 1.0 D of emmetropia). (17) Only the 44.5% and 63.4% of hyperopic eyes achieved a MRSE within ± 0.5 D and 1.0 D of emmetropia, respectively. (27) These results do not meet most of the FDA targets for predictability.

Efficacy Index

Compared with the hyperopia group, the EI was higher at almost all time points in the two myopia groups. In myopia group 1, the EI ranged from .61 to 1.157. The EI increased over the first year to its highest value (SI, 1.157) at 1 year and then declined over the next 4 years. In myopia group 2, the EI ranged from 0.74 to 0.95. In the hyperopia group, the EI ranged from 0.58 to 0.71. Like myopia group 1, the EI increased over the first year, and generally decreased over the final 4 years in the second myopia group and the hyperopia group. (27)

Safety Index

The SI was higher in myopia group 1 compared with myopia group 2 and the hyperopia group at all follow-up time points. In myopia group 1, the remained quite stable around 1.40 to 1.41 for the first 3 years and then declined to 1.30 in the final 2 years of follow-up. In the second myopia group, the SI was more variable ranging from 1.17 at 1 year to 0.99 at 5 years. In the hyperopia group, the overall trend was an increase in the SI over time from 0.86 at 3 months to 1.25 (the highest value reported for this group) at 5 years. (27)

Best Spectacle Corrected Visual Acuity

Although a loss of two or more Snellen lines of BSCVA is the primary criterion of safety, it was not reported in the study. The safety index (ratio of the mean postoperative BSCVA to the mean preoperative BSCVA) varied by group and over time. In myopic eyes, the safety index was substantially higher in group 1 than group 2 at all time points (e.g. at 3 months, the safety index was 1.41 and 1.11 in groups 1 and 2, respectively), and it decreased over time in both groups. While the safety index for hyperopic eyes was much lower than both groups 1 and 2 at all time points (e.g. at 3 months the safety index in hyperopic eyes was 0.86), it increased over time. (27)

Complications and Adverse Events

Complications were uncommon and occurred in less than 1% of all eyes. However, three major adverse events were observed during the follow-up period: retinal detachment (1 eye, .25%), macular haemorrhage (1 eye, .25%), and nuclear cataract development (2 eyes, 1 patient, .5%). (27)

Appendix 3: GRADE Tables

Efficacy Studies

Note that when studies were included in the GRADE analysis, three of the iris-fixated lens studies (Stulting, Silva, and Lombardo) were counted as one study because they report the results for the same patients but for different outcomes or at different time points. Similarly, two of the posterior chamber lens studies (ITM 2003 and 2004) were treated as one for the same reason.

Table A1:

GRADE Assessment of the Literature for Iris-Fixated Lenses for Myopia
No of
studies
DesignLimitationsQuality assessmentImprecisionOther
considerations
Overall
Quality
InconsistencyIndirectness
Uncorrected Visual Acuity
7Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Predictability
7Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
Best Spectacle Corrected Visual Acuity
5Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟLOW
Efficacy Index
5Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Safety Index
4Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
Manifest Refraction Spherical Equivalent
8Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Adverse Events
7Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
1Downgraded due to serious limitations including use of data from both eyes of most patients without correction in analyses for within-subject correlation and high loss to follow-up in most studies.
2Upgraded due to a strong association as patients move from being unable to see uncorrected to good uncorrected vision. While there was no control group for comparison, the natural history of refractive errors in the age group included in these studies suggests that visual acuity would remain the same or worsen, but not improve.

Table A2:

GRADE Assessment of the Literature for Iris-Fixated Lenses for Hyperopia
No of
studies
DesignLimitationsQuality assessmentImprecisionOther
considerations
Overall
Quality
InconsistencyIndirectness
Uncorrected Visual Acuity
1Observational studiesserious1no serious inconsistencyno serious indirectnessserious2strong association3[plus sign in circle]ΟΟΟ
VERY LOW
Predictability
1Observational studiesserious1no serious inconsistencyno serious indirectnessserious2none[plus sign in circle]ΟΟΟ
VERY LOW
Best Spectacle Corrected Visual Acuity
1Observational studiesserious1no serious inconsistencyno serious indirectnessserious2strong association3[plus sign in circle]ΟΟΟ
VERY LOW
Efficacy Index
1Observational studiesserious1no serious inconsistencyno serious indirectnessserious2strong association3[plus sign in circle]ΟΟΟ
VERY LOW
Manifest Refraction Spherical Equivalent
1Observational studiesserious1no serious inconsistencyno serious indirectnessserious2strong association3[plus sign in circle]ΟΟΟ
VERY LOW
Adverse Events
1Observational studiesserious1no serious inconsistencyno serious indirectnessserious2none[plus sign in circle]ΟΟΟ
VERY LOW
1Downgraded due to serious limitations including use of data from both eyes of most patients without correction in analyses for within-subject correlation and high loss to follow-up in most studies.
2Downgraded due to sparse data as only one study reported on this outcome.
3Upgraded due to a strong association as patients move from being unable to see uncorrected to good uncorrected vision. While there was no control group for comparison, the natural history of refractive errors in the age group included in these studies suggests that visual acuity would remain the same or worsen, but not improve.

Table A3:

GRADE Assessment of the Literature for Posterior Chamber Lenses for Myopia
No of
studies
DesignLimitationsQuality assessmentImprecisionOther
considerations
Overall
Quality
InconsistencyIndirectness
Uncorrected Visual Acuity
4Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Predictability
2Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
Best Spectacle Corrected Visual Acuity
2Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Efficacy Index
3Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Safety Index
2Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
Manifest Refraction Spherical Equivalent
4Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Adverse Events
5Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
1Downgraded due to serious limitations including use of data from both eyes of most patients without correction in analyses for within-subject correlation and high loss to follow-up in most studies.
2Upgraded due to a strong association as patients move from being unable to see uncorrected to good uncorrected vision. While there was no control group for comparison, the natural history of refractive errors in the age group included in these studies suggests that visual acuity would remain the same or worsen, but not improve.

Table A4:

GRADE Assessment of the Literature for Posterior Chamber Lenses for Hyperopia
No of
studies
DesignLimitationsQuality assessmentImprecisionOther
considerations
Overall
Quality
InconsistencyIndirectness
Predictability
1Observational studiesserious1no serious inconsistencyno serious indirectnessserious2none[plus sign in circle]ΟΟΟ
VERY LOW
Best Spectacle Corrected Visual Acuity
1Observational studiesserious1no serious inconsistencyno serious indirectnessserious2strong association3[plus sign in circle]ΟΟΟ
VERY LOW
Manifest Refraction Spherical Equivalent
1Observational studiesserious1no serious inconsistencyno serious indirectnessserious2strong association3[plus sign in circle]ΟΟΟ
VERY LOW
Adverse Events
1Observational studiesserious1no serious inconsistencyno serious indirectnessserious2none[plus sign in circle]ΟΟΟ
VERY LOW
1Downgraded due to serious limitations including use of data from both eyes of most patients without correction in analyses for within-subject correlation and high loss to follow-up in most studies.
2Downgraded due to sparse data as only one study reported on this outcome.
3Upgraded due to a strong association as patients move from being unable to see uncorrected to good uncorrected vision. While there was no control group for comparison, the natural history of refractive errors in the age group included in these studies suggests that visual acuity would remain the same or worsen, but not improve.

Table A5:

GRADE Assessment of the Literature for Posterior Chamber Lenses for Myopic Astigmatism
No of
studies
DesignLimitationsQuality assessmentImprecisionOther
considerations
Overall
Quality
InconsistencyIndirectness
Uncorrected Visual Acuity
2Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Predictability
2Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
Best Spectacle Corrected Visual Acuity
2Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Efficacy Index
1Observational studiesserious1no serious inconsistencyno serious indirectnessserious3strong association2[plus sign in circle]ΟΟΟ
VERY LOW
Safety Index
1Observational studiesserious1no serious inconsistencyno serious indirectnessserious3none[plus sign in circle]ΟΟΟ
VERY LOW
Manifest Refraction Spherical Equivalent
2Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Refractive Cylinder
2Observational studiesserious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Adverse Events
2Observational studiesserious1no serious inconsistencyno serious indirectnessNo serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
1Downgraded due to serious limitations including use of data from both eyes of most patients without correction in analyses for within-subject correlation and high loss to follow-up in most studies.
2Upgraded due to a strong association as patients move from being unable to see uncorrected to good uncorrected vision. While there was no control group for comparison, the natural history of refractive errors in the age group included in these studies suggests that visual acuity would remain the same or worsen, but not improve.
3Downgraded due to sparse data as only one study reported on this outcome.

Comparative Studies

Table A6:

GRADE Assessment of the Literature Comparing pIOLs with LASIK for the Treatment of Myopia
No of
studies
DesignLimitationsQuality assessmentImprecisionOther
considerations
Overall
Quality
InconsistencyIndirectness
Uncorrected Visual Acuity (% eyes seeing ≥ 20/20 or ≥ 20/40)
3Observational studiesvery serious1no serious inconsistencyserious2no serious imprecisionstrong association3[plus sign in circle]ΟΟΟ
VERY LOW
Predictability of Refraction
3Observational studiesvery serious1no serious inconsistencyserious2no serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
Stability of Refraction
3Observational studiesvery serious1no serious inconsistencyserious2no serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
Manifest Refraction Spherical Equivalent
2Observational studiesvery serious1no serious inconsistencyserious2no serious imprecisionstrong association3[plus sign in circle]ΟΟΟ
VERY LOW
Refractive Cylinder
2Observational studiesvery serious1no serious inconsistencyserious2no serious imprecisionstrong association3[plus sign in circle]ΟΟΟ
VERY LOW
Best Spectacle Corrected Vision (Gain/Loss Snellen Lines)
3Observational studiesvery serious1no serious inconsistencyserious2no serious imprecisionstrong association3[plus sign in circle]ΟΟΟ
VERY LOW
Additional Refractive Surgeries
3Observational studiesvery serious1no serious inconsistencyserious2no serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
Adverse Events
3Observational studiesvery serious1no serious inconsistencyserious2no serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
1Downgraded due to serious limitations including use of data from both eyes of most patients without correcting the analysis for the within-subject correlations, selection bias (unmatched study groups and attrition bias); and inclusion of additional refractive surgeries in results.
2Three studies compared pIOLs with older LASIK techniques which may be less accurate and precise than the current wavefront-guided laser systems.
3Upgraded due to a strong association as patients move from being unable to see uncorrected to good uncorrected vision. While there was no control group for comparison, the natural history of refractive errors in the age group included in these studies suggests that visual acuity would remain the same or worsen, but not improve.

Table A7:

GRADE Assessment of the Literature Comparing pIOLs with LASIK for the Treatment of Myopic Astigmatism
No of
studies
DesignLimitationsQuality assessmentImprecisionOther
considerations
Overall
Quality
InconsistencyIndirectness
Uncorrected Visual Acuity
2observational studiesVery serious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Predictability of Refraction
2observational studiesVery serious1no serious inconsistencyno serious indirectnessno serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
Stability of Refraction
1observational studiesVery serious1no serious inconsistencyno serious indirectnessno serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
Manifest Refraction Spherical Equivalent
1observational studiesvery serious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Refractive Cylinder
1observational studiesvery serious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Best Spectacle Corrected Vision (Gain/Loss Snellen Lines)
2observational studiesvery serious1no serious inconsistencyno serious indirectnessno serious imprecisionstrong association2[plus sign in circle][plus sign in circle]ΟΟ
LOW
Additional Refractive Surgeries
1observational studiesvery serious1no serious inconsistencyno serious indirectnessno serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
Adverse Events
1observational studiesvery serious1no serious inconsistencyno serious indirectnessno serious imprecisionnone[plus sign in circle]ΟΟΟ
VERY LOW
1Downgraded due to serious limitations including use of data from both eyes of most patients without correcting the analysis for the within-subject correlations, selection bias (unmatched study groups and attrition bias); no sample size calculations; and inclusion of additional refractive surgeries in results.
2Upgraded due to a strong association as patients move from being unable to see uncorrected to good uncorrected vision. While there was no control group for comparison, the natural history of refractive errors in the age group included in these studies suggests that visual acuity would remain the same or worsen, but not improve.

Table A8:

GRADE Assessment of the Literature Comparing pIOLs with PRK for the Treatment of Myopic Astigmatism
No of
studies
DesignLimitationsQuality assessmentImprecisionOther considerationsOverall
Quality
InconsistencyIndirectness
UCVA, BSCVA, MRSE, Contrast Sensitivity, Refractive Cylinder
1Randomized trialsvery serious1no serious inconsistencyno serious indirectnessserious2strong association3[plus sign in circle][plus sign in circle]ΟΟ
LOW
Predictability, Stability of Refraction, Adverse Events
1Randomized trialsvery serious1no serious inconsistencyno serious indirectnessserious2none[plus sign in circle]ΟΟΟ
VERY LOW
1Downgraded due to serious limitations. The study scored 1 out of 5 on Jadad scale (method of randomization not reported, no blinding, no description of reason for dropouts/withdrawals). As well, the study used results for both eyes of most patients, but did not correct for the within-subject correlated data in the analysis.
2Downgraded because the evidence is based on only one study of 46 patients (23 in each group).
3Upgraded due to a strong association as patients move from being unable to see uncorrected to good uncorrected vision. While there was no control group for comparison, the natural history of refractive errors in the age group included in these studies suggests that visual acuity would remain the same or worsen, but not improve.

Table A9:

GRADE Assessment of the Literature Comparing pIOLs with CLE for the Treatment of Myopia
No of
studies
DesignLimitationsQuality assessmentImprecisionOther
considerations
Overall
Quality
InconsistencyIndirectness
All Outcomes (Predictability, Manifest Refraction Spherical Equivalent, Best Spectacle Corrected Visual Acuity, Endothelial Cell Loss, Adverse Events)
1observational studiesvery serious1no serious inconsistencyno serious indirectnessserious
(sparse data)2
strong association3[plus sign in circle]ΟΟΟ
VERY LOW
1Downgraded due to serious limitations including use of data from both eyes of most patients with no correction in the analysis for the within-subject correlation, different enrolment criteria for the study groups, and high loss to follow-up in both groups after 2 years.
2Downgraded because the evidence is based on only one study of 39 patients (21 and 18 in the pIOL and CLE groups, respectively)
3Upgraded due to a strong association as patients move from being unable to see uncorrected to good uncorrected vision. While there was no control group for comparison, the natural history of refractive errors in the age group included in these studies suggests that visual acuity would remain the same or worsen, but not improve.

Appendix 4: Results of Systematic Review

Table A10:

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Study Results
BSCVA refers to best spectacle corrected visual acuity; cat, category; CI, confidence interval; ECD, endothelial cell density; endpt, endpoint; e, eyes; fup, follow-up; HC, Health Canada; inc, increase; ICL, implantable collamer lens; IOP, intraocular pressure; mo, months; NR, not reported; preop, preoperative, postop, postoperative; SD, standard deviation; SE, spherical equivalent; UCVA, uncorrected visual acuity; VA, visual acuity; vis, vision; wk, week; yr, year

Notes

Suggested Citation

This report should be cited as follows:

Medical Advisory Secretariat. Phakic intraocular lenses for the treatment of refractive errors: an evidence-based analysis. Ontario Health Technology Assessment Series 2009;9(14).

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About the Medical Advisory Secretariat

The Medical Advisory Secretariat is part of the Ontario Ministry of Health and Long-Term Care. The mandate of the Medical Advisory Secretariat is to provide evidence-based policy advice on the coordinated uptake of health services and new health technologies in Ontario to the Ministry of Health and Long-Term Care and to the healthcare system. The aim is to ensure that residents of Ontario have access to the best available new health technologies that will improve patient outcomes.

The Medical Advisory Secretariat also provides a secretariat function and evidence-based health technology policy analysis for review by the Ontario Health Technology Advisory Committee (OHTAC).

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The information gathered is the foundation of the evidence to determine if a technology is effective and safe for use in a particular clinical population or setting. Information is collected to understand how a new technology fits within current practice and treatment alternatives. Details of the technology’s diffusion into current practice and input from practising medical experts and industry add important information to the review of the provision and delivery of the health technology in Ontario. Information concerning the health benefits; economic and human resources; and ethical, regulatory, social and legal issues relating to the technology assist policy makers to make timely and relevant decisions to optimize patient outcomes.

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Disclaimer

This evidence-based analysis was prepared by the Medical Advisory Secretariat, Ontario Ministry of Health and Long-Term Care, for the Ontario Health Technology Advisory Committee and developed from analysis, interpretation, and comparison of scientific research and/or technology assessments conducted by other organizations. It also incorporates, when available, Ontario data, and information provided by experts and applicants to the Medical Advisory Secretariat to inform the analysis. While every effort has been made to reflect all scientific research available, this document may not fully do so. Additionally, other relevant scientific findings may have been reported since completion of the review. This evidence-based analysis is current to the date of publication. This analysis may be superseded by an updated publication on the same topic. Please check the Medical Advisory Secretariat Website for a list of all evidence-based analyses: http://www.health.gov.on.ca/ohtas.

List of Abbreviations

BSCVA
Best spectacle corrected visual acuity
CLE
Clear lens extraction
EI
Efficacy index
GRADE
Grading of Recommendations Assessment, Development and Evaluation
HTA
Health technology assessment
IOL
Intraocular lens
LASIK
Laser-assisted in situ keratomileusis
LASEK
Laser-assisted sub-epithelial keratomileusis
logMAR
Logarithm of the minimum angle of resolution
MRSE
Manifest refraction spherical equivalent
Nd:YAG
Neodymium:yttrium-aluminum-garnet
pIOL
Phakic intraocular lens
PMMA
Polymethyl methacrylate
PRK
Photorefractive keratectomy
RCT
Randomized controlled trial
SI
Safety index
UCVA
Uncorrected visual acuity

Footnotes

1The other iris-fixated lenses included in Chen et al. (23) were the first generation Worst-Fechner biconcave iris-claw IOL (318 eyes) and the Artiflex IOL (72 eyes), which are not licensed by Health Canada.

2The other posterior chamber lenses included in Chen et al. (23) were the Russian design plate silicone IOL (Fyodorov), the Chiron-Adatomed IOL, and the PRK.

3The 144 anterior subcapsular cataracts included 4 eyes with both anterior subcapsular cataracts and cortical opacities, 3 eyes with both anterior subcapsular cataracts and nuclear sclerosis cataracts, and 1 eye with both anterior subcapsular cataracts and posterior subcapsular cataracts. (23)

4Two of the posterior chamber lens studies (24;25) and two iris-fixated lens studies (13;26) reported results for the same trials/patient populations. These studies were not excluded as duplicates as they report different time points or outcomes. However, results for any outcomes that were reported in 2 or more of these studies were based only on the study that provides the most complete results.

536% includes only the myopic and hyperopic eyes. The eyes with astigmatism were excluded from this report because they received a lens that is not licensed by Health Canada.

6Emmetropia occurs when parallel rays are focused exactly on the retina and vision is perfect. This corresponds to a MRSE of 0.0 diopters.

7Results from Chang et al. (31) and Stulting et al. (26) were excluded from the weighted mean calculations because the sample sizes at the follow-up time point were not provided in the text.

8Six studies provided the EI in the reported results. For 3 studies, while the EI was not reported, it was possible to calculate the value using the mean preoperative BSCVA and mean postoperative UCVA provided in the study. However, for 7 studies, there was inadequate data to calculate the EI, so the authors were contacted to ask for the EI or raw data. We were unable to contact 2 authors as the available email addresses were not active. Two authors responded to our request and provided us with the necessary information to include the studies in our analysis (1 of these authors provided us with combined EI data as only stratified results by myopia severity were reported in the paper).

9The 3 and 4 year data were based on the Lackner et al. results, but because no other studies reported results at these time points, weighted means were not used to calculate the EIs, so they are not affected by inflated sample size weights.

10The distance between the eye’s natural crystalline lens and the pIOL is called the vault. Vaulting should provide maximal clearance between the pIOL and the eye’s lens. However, if the lens is over or under vaulted, then it comes into contact with structures in the eye and can cause problems.

11FDA target for UCVA for high myopia (applies to eyes with preoperative BSCVA of 20/20 or better):

  • At least 75% of eyes achieve UCVA of 20/40 or better

12A clinically significant change is defined as a gain or loss of 2 or more Snellen lines of BSCVA. (41)

13The defocus equivalent refraction is a measure of the refractive state of the eye which takes into account residual astigmatism and is calculated as the sphere (respecting the sign) plus half the cylinder (respecting the sign) plus half the cylinder (ignoring the sign). (42)

14PRK custom ablation techniques for high myopia did not exist at the time of the study

15Mitomycin C was used to aid in the healing process after PRK

16The results did not specify whether the reported endothelial cell loss was at 6 months or 1 year.

17It was not specified when the postoperative interview regarding satisfaction and visual disturbances was conducted.

18Arne (48) did not report UCVA, so this observation does not include the comparison between pIOLs and CLE.

19Arne (48) did not report stability, so this observation does not include the comparison between pIOLs and CLE.

20Toric pIOLs are designed to treat astigmatism, whereas, non-toric pIOLs cannot correct astigmatism.

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