When deciding the correct intervention for ectopic lentis, it is important to formulate a comprehensive plan regarding the diagnosis, surgical timing, surgical approach and plan for visual rehabilitation. As discussed previously, identifying a cause of ectopic lentis is important because this finding can help to diagnoses life threatening associated conditions. After a cause is identified, the next question a surgeon asks is whether the patient needs surgery for visual function or to prevent long-term complications. If a patient can achieve visual rehabilitation and maturation with glasses and/or contact-lens correction, many times surgery can be delayed or prevented. Despite maximal conservative management, Romano et al. reports ametropic amblyopia in 50% of patients with familial ectopic lentis. The vision in these patients ranged from 20/50 to 20/200.2
If optimal correction cannot be accomplished, surgical removal of the lens may be warranted.3
If considering surgery, a thorough ophthalmic examination must be completed, as findings can help the surgeon plan for the anticipated surgery. By examining the anterior chamber depth and angle, a surgeon can better access the degree and direction of subluxation. Looking at the lens under undilated and dilated conditions can aid in assessing the degree and location of zonular dysfunction.3
A full retinal examination must be conducted, especially in patients with Marfan syndrome, as they can be predisposed to retinal holes.4
It is also important to consider risk of thromboembolic events in patients with ectopic lentis secondary to homocystinuria.1
Communication is paramount with the anesthesiologist in this situation and some surgeons advocate bilateral surgery to minimize the number of general anesthetics.1
Once surgical removal is deemed necessary to improve a child’s vision and/or to prevent irreversible amblyopia, the question is then how best to remove the subluxed lens. Traditionally, in the pre-automated vitrectomy era, removal of subluxed crystalline lens in young eyes was met with extremely high rates of complication such as vitreous loss and retinal detachments with variable and modest visual gains.1,5–7
The advent of the close-system, automated, irrigation-vitrectomy was a game-changer for approaching these cases. Investigators favor either a limbal, anterior approach or a pars-plana approach. From either approach, there are generally good outcomes and minimal complications.5–10
summarizes the results of primary lensectomy via either the anterior or pars-plana approach. While the closed system allows for safe removal of the subluxed lens, the key to success and to minimize complications in all these reports is a thorough and meticulous removal of the vitreous gel and to make sure that there are no vitreous incarcerations that would potentiate retinal detachments. Theoretically, a pars-plana approach may allow for more thorough vitreous removal and spot pre-existing or iatrogenic retinal tears; however, the published literature does not support the superiority of the pars-plana approach over a limbal approach. While we utilized an anterior/limbal approach, we feel that the choice is up to the surgeon and his/her comfort level and expertise with either approach.
Primary lensectomy for ectopia lentis in pediatric patients.
Once the crystalline lens is removed, optical rehabilitation of the child with aphakia and no capsular support presents the next therapeutic challenge. Options include aphakic spectacles, contact lens, angle-supported anterior chamber intraocular lens implant (ACIOL),11,12
anterior chamber iris-enclavated IOL,13
posterior-chamber iris-fixated IOL implant,14,15
posterior-chamber capsule-placed IOL centered with a capsular tension ring,16
or a SFIOL implant.11,17–24
Each of these approaches has inherent limitations and problems. Wearing aphakic spectacles is the safest but least physiologic method of optical correction, often resulting in aniseikonia and visual distortion. Aphakic glasses are not well tolerated by young children because of the glasses’ weight, awkward appearance, prismatic distortion, and constriction of visual fields. Contact lens use requires ongoing care, has an inherent increased risk of corneal infection, and contact-lens intolerance can develop.25
Both of these approaches are limited by children’s and their family’s compliance with using the vision-correcting devices with the constant specter of refractive amblyopia. In aphakia, good visual acuity outcomes are highly dependent on compliance with amblyopia therapy in the first several years of life. Compliance with occlusion therapy is often variable among patient populations. Epley et al. reported worse visual outcomes in their younger patient cohort due to poor compliance with optical rehabilitation and occlusion.11
With that being said, the vast majority of the aphakic patients from the series described previously of primary lensectomy achieved good corrected visual acuities with 70–100% achieving 20/60 or better 5–10
and as high as 93% achieving 20/40 or better in one series ().7
IOLs obviously offer the advantage of permanent compliance, minimal aniseikonia, and an early and generally predictable refractive result. Relative short-term outcomes (9–16 months) with ACIOLs have been reported to provide good visual outcomes in young patients with no significant complications.12
However, ACIOL implants in the pediatric population generally have had significant long-term complications, such as endothelial cell loss, corneal decompensation, iris-sphincter erosion and pupillary ectopia.26,27
Because of these problems, posterior-chamber SFIOLs are generally preferred over ACIOLs in aphakic children with inadequate capsular support for PCIOL implantation,11
and we agree with this general preference. Nonetheless, alternatives to conventional angle-support ACIOLs and SFIOLs do exist. The Artisan iris-enclavated IOLs have been used in a very limited basis in pediatric patients with subluxed crystalline lenses with good short-term outcomes while they have enjoyed wider usage in cases of congenital cataracts.13
Also, posterior-chamber iris-fixated IOLs have been utilized with longer follow-up likewise with reported good visual outcomes and low complication rates in one paper 14
while another group reported good visual outcomes but with significant rates (33%) of IOL dislocation due to IOL slippage.15
Lastly, it is possible to implant a conventional capsular tension ring or a modified scleral-fixated capsular tension ring to allow in-the-bag placement of an IOL.16
In this report of 37 eyes, the mean post-operative BSCVA was 20/78 (range 20/32–20/200). The authors reported that if amblyopic eyes were removed from the analysis, then the mean BSCVA improved to 20/50. However, posterior capsule opacification requiring intervention occurred in 83.8% of patients (31 out of 37) during the median follow-up period of 27 months (range 1–59 months).
Scleral-fixated IOLs are the most popular means of implanting an IOL in an aphakic pediatric eye. Nonetheless, much more is known about the outcomes and complications of SFIOL in the adult population. Hyphema or vitreous hemorrhage as a complication is not surprising, considering that scleral suturing of a PCIOL requires that the needle pass through vascular tissue. In most cases, the bleeding resolves spontaneously.28
It has been proposed that placing the sutures anteriorly (0.5–1.0 mm behind the surgical limbus) to allow the lens to sit in the true sulcus space and avoid the vascular ciliary body may reduce the risk of bleeding.29
However there is discussion about the location of the true sulcus space relative to the surgical limbus.30,31
The caveat to these debates is that these reports pertain to experiment in adult cadaveric eyes and surgery in adult eyes and not pediatric eyes. A survey of reports regarding SFIOL in pediatric eyes found that, when reported, the location of suture placement ranged from 0.5 to 2.0 mm posterior to the limbus.17–19,23,24
With the exception of one report, there were relatively few incidences of intraocular bleeding, and in all cases where they are encountered, they are all self-resorbing within days. This one exception reported intraocular bleeding in 13 out of 25 eyes (52%) in which the suture was placed 1.0 mm posterior to the limbus.24
We tend to pass the suture 1.5 mm posterior to the limbus, and in our relatively small series, we did not encounter intraocular hemorrhage. It has additionally been suggested that to prevent intraocular bleeding that the surgeon take care to maintain a pressurized globe at all times during the surgery and to minimize tissues traversed during transscleral needle passes, and we agree this recommendation.32
summarizes several series in the literature, including the current series, of pediatric patients that underwent either primary or secondary SFIOLs along with the complications and visual outcomes.
Scleral-fixated intraocular lenses (SFIOL) in pediatric patients.
Retinal detachment is a potentially devastating complication after implantation of a SFIOL. In one series of adult eyes, retinal detachment occurred in 4.9% of 122 eyes during a follow-up period of 42 months.33
Again the reported rate of retinal detachment after SFIOLs in children seems to be much lower. In the papers reviewed, there was one case out of 197 (). The adult eyes that suffered retinal detachments also included those that had suffered previous trauma; therefore, the cause of retinal detachment may not be due directly to the surgical implantation of a SFIOL.34
The pediatric series reviewed also included eyes that were traumatized; additionally, patients with Marfan syndrome feature prominently in the pediatric series where there is a known increased risk of retinal detachments. It remains interesting to speculate why there seems to be a lower risk of retinal detachment in pediatric eyes.
One of the significant complications in adults who have undergone sutured IOLs is the eventual erosion and exposure of the fixation knot through the conjunctiva. Long-term transscleral suture exposure rates of 5% to 50% have been reported when sutures were covered with conjunctiva only, and exposure rates of 14.7–17.9% have been reported when sutures were covered with sclera flaps.35–37
Again, the rate of suture erosion in pediatric cases seems to be lower. Our review of the literature revealed six cases (). In all pediatric case series, the sutures were buried under partial-thickness scleral flaps, which we advocate, which may have reduced the risk of erosion and exposure. It is also possible that exposure of suture knots was not noted in pediatric case series due to the generally short follow-up periods of published reports. Additionally, we speculate that the healthier and thicker conjunctiva and tennon’s capsule of pediatric eyes may help to prevent frank suture erosion.
Besides symptomatic foreign-body sensation as a result of suture erosion and exposure, the main fear of having an exposed suture is that of endophthalmitis as infecting organisms may gain access to the eye via exposed sutures. Late endophthalmitis after SFIOL implantation is a real danger.38
Although scleral flaps reduce the risk of suture exposure, in the long term, suture ends can erode through partial-thickness scleral flaps and conjunctiva. Indeed, there is one reported case of a late-onset endophthalmitis in a pediatric eye with SFIOL that developed 3 years after the surgery.24
Unfortunately, there is no description of whether suture exposure was seen or part of the pathophysiology.
A disturbing complication of transscleral fixation of IOLs is the late failure of the 10-0 polypropylene sutures through degradation or trauma, which would result in lens decentration or subluxation. Histopathologic findings have shown a lack of significant fibrosis around the lens loops, suggesting that the suture remains the only support for the SFIOLs.37
Polypropylene suture is considered to be non-absorbable; however, they do degrade slowly over time and are not “permanent”.39
One report of largely adult patients found late polypropylene suture breakage in 16 of 61 eyes (26.2%) occurring about 50 months after IOL fixation.40
Another report of adult eyes with a shorter duration of follow-up (24 months) found a lower rate of suture breakage (2.2%) in 89 eyes after penetrating keratoplasty and SFIOL implantation.41
In contrast, in another report with more than 10 years of follow-up of 16 adult patients with SFIOLs, no cases of suture breakage occurred.42
Therefore, while perhaps not a certainty, the concern is that 10-0 polypropylene sutures degrade and eventual breakage will increase over time with resultant IOL dislocation. This is of obvious concern for the pediatric patient. In pediatric series, we encountered a total of 10 cases of SFIOL dislocation due to suture breakage ().23–24
These reports had the longest average follow-up periods of 5.1 and 6.8 years of the surveyed series. In one report, the author noted that the suture breakage occurred at 3.5, 5, 6, and 8 years.23
Additionally, the author reported that a survey of pediatric ophthalmologists revealed an additional 10 eyes with dislocated SFIOLs from broken 10-0 polypropylene sutures and three additional eyes from another published series. In all cases, the situation was successfully dealt with surgically with good retention of visual acuities. In another report, the average time to suture breakage and IOL dislocation was 8.7 ± 1.2 years; in this report, all IOLs were explanted.24
As a result, several recommendations have been put forth to reduce the risk of suture breakage and IOL dislocation. These include the usage of multiple sutures, thicker sutures (9-0 polypropylene), and different suture materials.23,24,32
Further research is needed to find an ideal method and/or material for fixation of IOLs to the sclera.
summarizes the results from the pediatric SFIOL reports in the literature. Additionally, it reports the visual outcomes reported. In general, the average best-vision ranges from approximately 20/60 to a bit shy of 20/30. Compared to reports of aphakic eyes with spectacle or contact-lens correction (), it would appear that fewer eyes with SFIOLs achieve 20/40 or better vision. However, one should keep in mind that eyes that come to SFIOLs oftentimes have failed or are intolerant of contact-lens correction or are unilateral aphakic eyes. As such there is likely a higher proportion of eyes with amblyopia in the SFIOL group, especially if the patient is young. In one report of a series of unilateral aphakic eyes, only 39% of the entire cohort achieved 20/40 or better vision after SFIOL implantation. In contrast, a subgroup analysis of patients from the cohort that became aphakic after 9 years of age, and thereby after the amblyopic age-range, revealed that 83% achieved 20/40 or better vision.11
In conclusion, vitrectomy techniques revolutionized the management of pediatric ectopia lentis cases due to the ability to successfully remove the subluxed crystalline lens and vitreous and avoid marked complications. The most important determinant of good visual outcome in these vulnerable eyes is amblyopia. If a child develops good vision before visually-significant lens subluxation, s/he should do well after surgery. If, however, the child is at risk of amblyopia or already has amblyopia, the visual outcome is much more guarded. Nonetheless, aggressive visual correction can still reverse the amblyopia trend. Our series with amblyopia in 6 out of 7 patients demonstrates that poor pre-operative vision can be improved if not reversed with intervention.
While the decision to implant an IOL at the time of lensectomy is a difficult one due to uncertainty about whether a child and his/her family have access to and/or will be able to comply with aphakic correction and amblyopia therapies, the low rate of complication from IOL implantation should prompt physicians treating these special patients to consider primary IOL implantation more frequently as a viable option. Even though the risks associated with IOL implantation in aphakic eyes are low and there is significant overlap of the complications from lensectomy and IOL implantation, there are, nonetheless, IOL-specific complications that are worrisome. The chief of these relates to the use of 10-0 polypropylene sutures in pediatric patient as was discussed previously. We feel that even though better methods and materials need to be developed to achieve longer-term safety for IOL implantation in the absence of capsular support, the surgical option should not be withheld from the pediatric patient facing permanent visual handicap from amblyopia. We feel that this is especially true in cases that will result in unilateral aphakia. A child with bilaterally subluxed lenses should either be bilaterally aphakic or have IOLs implanted in both eyes.