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A 56-year-old Caucasian male was referred to the corneal service for the management of post penetrating keratoplasty (PK) astigmatism in his right eye. He had also previously undergone trabeculectomy and cataract surgery in the same eye. Corneal topography showed high postoperative astigmatism of 8.74 dioptres. He was intolerant to contact lens wear and could not tolerate spectacle correction due to high anisometropia. He proceeded to undergo a secondary ‘piggyback’ toric intraocular lens (IOL) insertion procedure with an improvement in his best corrected visual acuity to 6/9. With the decrease in anisometropia he was able to tolerate a full spectacle correction. We report the use of a new injectable sulcus fixated toric piggyback IOL for the correction of post PK astigmatism in a pseudophakic eye. To the best of our knowledge this is the first report on the use of this new ‘add on’ IOL for this clinical condition.
Penetrating keratoplasty (PK) has proven to be an effective surgical option for the treatment of both anterior and posterior corneal disorders. Although the survival rates of the corneal grafts are over 80% for non-inflammatory corneal disorders,1 visual rehabilitation following PK continues to remain a challenge. Unpredictable wound healing caused by the full thickness wound can lead to high degrees of hyperopia, myopia and irregular astigmatism. The prevalence of high degree of corneal astigmatism (over 5 D) following PK has been reported to be between 15% and 31%.2 Minimal amounts of astigmatism and anisometropia may be managed with spectacle correction. Contact lens fitting can be challenging due to irregular corneal topography and poor visual quality. Several surgical options have been described in the past in correcting post PK astigmatism. This could broadly be classified as surgical procedures on the corneal graft like astigmatic keratotomy (AK),3 wedge excision with or without AK,4 photorefractive keratectomy (PRK)5 and laser-assisted in situ keratomileusis (LASIK)6 and intraocular procedures, which include piggyback intraocular lens (IOL) and toric anterior chamber (AC) iris fixated IOL.7–10 We herein report the use of new injectable sulcus fixated toric piggyback IOL for the correction of post PK astigmatism in a pseudophakic eye. To the best of our knowledge this is the first report on the use of this new ‘add on’ IOL for this clinical condition.
A 56-year-old Caucasian male was referred to the corneal service for the management of post PK astigmatism in his right eye (RE). His past ocular history was significant for a PK procedure performed in his RE 27 years ago for keratoconus. He also underwent a trabeculectomy in that eye for medically uncontrolled glaucoma 6 years following the PK procedure. In 2000 he underwent a phacoemulsification with implantation of a three piece acrylic IOL (AcrySof MA30BA; Alcon Laboratories, Fort Worth, Texas, USA) procedure combined with AK. On examination he had an uncorrected visual acuity of counting fingers at 2 m RE and 6/9 in the left eye (LE). Best spectacle corrected visual acuities (BCVA) were 6/36 RE with a −7.5/+7.0 at 120 ° and 6/7.5 LE with a −0.75/+1.50 at 140. Slit lamp biomicroscopy showed a well-centred clear corneal graft with no sutures, and a posterior chamber IOL well centred within the capsular bag. Examination of the LE showed mild keratoconus, which had remained stable for many years with no change to the manifest refraction. Intraocular pressures were within normal limits with no anti-glaucoma medication. Fundus examination showed a cup disc ratio of 0.5 OD and 0.2 OS and a normal looking retina and fovea.
Corneal topography (iTrace; Tracey Technologies, Houston, Texas, USA) of the RE showed high post PK astigmatism of 8.74 D with keratometry readings of 47.88 D at 129 ° and 39.14 D at 42 ° (figure 1). Preoperatively the corneal graft had a central endothelial cell density of 1196/mm2.
He could not tolerate spectacle correction due to high anisometropia and had become intolerant to contact lens wear. Having suffered with poor unaided vision in the RE for many years he was motivated to try any surgical procedure to improve the vision in that eye. Several surgical options including LASIK, PRK and secondary piggyback toric IOL were discussed. After discussing in detail the risks and the benefit of each he opted to undergo a secondary piggyback toric IOL procedure. Preoperative assessment included manifest refraction, corneal topography (iTrace; Tracey Technologies), specular microscopy and axial length measurement (IOL Master; Carl Zeiss Meditec, Oberkochen, Germany). Based on this a custom sulcus fixated injectable piggyback IOL (Sulcoflex; Rayner, Hove, England) was manufactured.
The procedure was performed under topical and intracameral anaesthesia (see supplementary video). Preoperatively the pupil was dilated with 2.5% phenylepherine and 1% cyclopentolate. Prior to the procedure using a marking pen the horizontal and the vertical meridians (90 ° and 180 °) of the cornea were marked under a slit lamp using the slit beam. Intraoperatively a Mendez gauge was used to mark the steep meridian on the cornea. Following a temporal paracentesis 0.1 ml of preservative free lidocaine was injected in the AC. A dispersive ophthalmic viscosurgical devise (OVD, VisCoat; Alcon, Fort Worth, Texas, USA) was used to fill the AC. A 2.75 mm posterior limbal incision was constructed superiorly. A dispersive OVD (Provisc; Alcon) was injected to the AC thus enabling the dispervise OVD to coat and protect the corneal endothelium in a similar fashion to the ‘soft-shell’ technique described during cataract surgery. Through the 2.75 mm wound the toric IOL was injected in to the ciliary sulcus using a disposable injector (figure 2). The axis marks on the IOL were aligned to the marks made on the cornea corresponding to the steep meridian (figure 3). Following the removal of OVD the orientation of the toric IOL was once again checked and the posterior limbal wound was closed with a single 10-0 nylon suture that was removed 4 weeks postoperatively. There were no intraoperative complications.
Postoperatively the eye was treated with topical ofloxacin (Exocin; Allergan, Irvine, California, USA) and dexamethasone (Maxidex; Alcon) four times a day for 3 weeks. At the end of 3 weeks topical ofloxacin was discontinued but the topical steroid was continued and was gradually tapered to once a day over a period of 6 months. At the end of 6 months he was kept at a maintenance dose of once a day. Following the procedure the unaided vision in the RE improved from CF at 1 m to 6/24. BCVA improved from 6/36 (with −7.5/+7.0 at 120 °) to 6/9 with −0.75/+3.50 at 110. With the decrease in anisometropia he was able to tolerate a full spectacle correction to the RE. The RE refraction remained stable at 6 month follow-up and specular microscopy at 6 months time gate showed a endothelial cell density of 1049 cells/mm2.
When dealing with post PK astigmatism the literature is heavily populated with several surgical techniques which can be broadly classified in to secondary surgical procedures performed on the corneal graft and intraocular procedures which involves implanting an IOL either in the anterior or posterior chambers. Of the secondary procedures performed on the corneal graft laser procedures like LASIK seem to be more predicable in correcting the post PK refractive error when compared to AK which primary corrects only the cylindrical component of the refractive error.11 However it can lead to flap complications like buttonhole, free cap and also to graft dehiscence. The use of PRK may lead to stromal haze and loss of BCVA.5
Off the intraocular techniques the use of secondary IOL is preferred to IOL exchange as it is considered to be less traumatic. The technique of implanting two IOLs together (piggybacking) was first described in 199312 where it was used to correct hyperopia in microphthalmos. Since then the method of implanting a second IOL (piggyback or add on IOL) in pseudophakic eyes is becoming increasingly popular. The use of piggyback IOLs to correct post PK refractive error was first described by Gayton et al.13 In their series of seven patients, there was an improvement in the total mean deviation spherical error from 3.41 D prior to surgery to 0.98 D afterwards. Since then Paul et al7 reported six eyes that underwent piggyback IOLs where the mean spherical equivalent reduced from −8.05 D preoperatively to −0.94 D postoperatively with no complications. Nuijts et al14 reported the largest series on the use of toric iris clip AC IOL (Artisan, Ophtec, Groningen, The Netherlands) for the correction of post PK astigmatism. Spherical equivalent was reduced from −4.90 ± 5.50 D before surgery to −0.96 ± 0.86 D at final follow-up. The endothelial cell loss was 7.6 ± 18.9% at 3 months and 16.6 ± 20.4% at 1 year. Although the visual outcomes are excellent, this rigid PMMA lens requires a large 5.3 mm incision. Such an incision after PK can lead to an unpredictable biomechanical response of the corneoscleral tissue to the incision and a greater variability in surgically induced astigmatism may be seen.
Park et al9 were the first to describe the use of a toric piggyback IOL to correct post PK astigmatism. They used a toric plate haptic IOL (Starr IOL, Vision Pharmaceuticals, Macclesfield, Cheshire, UK) through a 2.8 mm incision in a 72-year-old female who although had excellent visual outcome went on to develop corneal graft failure secondary to endothelial rejection 14 months after the piggyback procedure. As specular microscopy was not performed it is unclear whether this patient was at risk of graft failure.
The other previously reported complications of piggyback IOLs include interlenticular opacification and hyperopic shift.13 15 These complications can be avoided by using a acrylic IOL and by placing the second lens in the ciliary sulcus.
The Sulcoflex is a hydrophilic acrylic injectable IOL with undulating haptics and posterior 10 ° haptic angulation which provides excellent rotational stability (figure 2). It has an overall length of 13.50 mm with 6.50 mm optic. The lens is supplied in a 0.9% saline solution in a pouched blister pack and is injected using a disposable soft tipped injector. The drawback of the current model is that the maximum cylindrical correction is only up to 6 D. However we are led to believe that the manufacturer is currently working on higher cylindrical corrections. This initial report suggests that this new sulcus fixated injectable toric IOL seems to provide excellent visual and refractive outcomes with good rotational stability. However a larger cohort and longer follow-up is necessary to assess the long-term effect of this lens.
Competing interests None.
Patient consent Obtained.