Implantation of the black diaphragm intraocular lens in congenital and traumatic aniridia.

OBJECTIVE: To evaluate the biometry accuracy, visual outcomes, and long-term changes in intraocular pressure after implantation of the black diaphragm intraocular (BDI) lens in cases of aniridia. DESIGN: Retrospective, interventional case series. PARTICIPANTS: Forty eyes of 35 patients with aniridia (15 eyes of congenital origin and 25 as a result of trauma). METHODS: Patient demographics, clinical evolution, and treatment were analyzed for each case undergoing implantation with the Morcher 67F BDI lens (Morcher GmBH, Stuttgart, Germany). MAIN OUTCOME MEASURES: Biometry accuracy, visual outcome, and the development of glaucoma and other complications in these eyes over a mean of 3.5 years. RESULTS: Using the recommended A constant of 118.7, the mean biometry prediction error was -0.12+/-0.44 diopters (D), with a mean absolute error of 1.47+/-0.29 D, equivalent to 80% of target eyes being within 2 D of predicted refraction. The prevalence of glaucoma increased from 10 (25%) of 40 eyes before surgery, to 22 (55%) of 40 eyes at 1 year after surgery. The best-corrected visual acuity in logarithm of the minimum angle of resolution (logMAR) units improved significantly in the 25 eyes with traumatic aniridia, from 1.34+/-0.22 to 0.54+/-0.16 (20/400 to 20/70; P<0.001). In contrast, no significant improvement was seen in the 15 eyes with congenital aniridia, whose preoperative logMAR visual acuity of 1.17+/-0.14 improved to 1.01+/-0.21 (20/300 to 20/200; P = 0.20). CONCLUSIONS: Biometry is reasonably accurate when implanting the BDI lens for aniridia. Glaucoma is the main complication and occurred immediately after surgery, suggesting a possible direct mechanical effect of the large BDI lens. Significantly better visual outcomes were seen when using the 67F BDI lens for traumatic aniridia compared with congenital aniridia. Implantation of the BDI lens in congenital aniridia therefore should be approached with caution, because the recreation of an iris diaphragm does not confer the expected optical benefits in these eyes.

Astigmatic keratotomy for post-keratoplasty astigmatism.

PURPOSE: To assess astigmatic keratotomy as a means of managing post-keratoplasty astigmatism in the era of excimer laser refractive surgery. SETTING: Moorfields Eye Hospital, London, England. METHODS: Fifty paired arcuate keratotomies were performed with refractive and topographic guidance. Refraction, uncorrected visual acuity, best corrected visual acuity, and visual acuity with the patient's preferred correction were measured before and after surgery. RESULTS: The median follow-up was 34 months. The mean cylinder was 9.13 diopters (D) preoperatively and 4.85 D postoperatively. The mean spherical equivalent refraction was -4.21 D preoperatively and -4.26 D postoperatively. The amount of cylinder reduction was correlated with the amount of pre-existing cylinder (P<.001). Thirty eyes (60%) gained and 1 eye (2%) lost Snellen acuity with preferred correction. In the remaining 19 eyes (38%), there was no change in acuity with preferred correction. The mean change in visual acuity with preferred correction was a gain of 1.5 Snellen lines. Three patients intolerant of spectacles or contact lenses before surgery became tolerant. Ten patients (20%) previously unsuitable for laser in situ keratomileusis (LASIK) because of high cylindrical error went on to have LASIK. CONCLUSIONS: Astigmatic keratotomy remains a useful, safe, relatively simple surgical procedure for treating post-keratoplasty astigmatism. Reduction in cylinder was correlated with pre-existing cylinder. Vision with preferred correction was improved in 60% of cases. High astigmatism reduced to a level at which more definitive refractive surgery such as LASIK became feasible.

Identification of novel mutations in the carbohydrate sulfotransferase gene (CHST6) causing macular corneal dystrophy.

PURPOSE: Macular corneal dystrophy (MCD) is a rare corneal dystrophy that is characterized by abnormal deposits in the corneal stroma, keratocytes, Descemet's membrane, and endothelium, accompanied by progressive clouding. It has been classified into three immunophenotypes--MCD types I, IA, and II--according to the serum level of sulfated keratan sulfate (KS) and immunoreactivity of the corneal tissue. Recently, mutations in a new carbohydrate sulfotransferase gene (CHST6) encoding corneal glucosamine N-acetyl-6-sulfotransferase (C-GlcNac-6-ST) have been identified as the cause of MCD. Mutation screening of the CHST6 gene has been undertaken to identify the underlying mutations in five unrelated British families with MCD. METHODS: DNA was extracted from venous blood obtained from all participants, and the coding region of CHST6 was amplified by polymerase chain reaction (PCR). The PCR products were analyzed by direct sequencing and restriction enzyme digestion. Enzyme-linked immunosorbent assay (ELISA) was performed to assess the presence of KS in serum from the probands of MCD-affected families participating in the study. RESULTS: Six novel missense mutations--four homozygous and two compound heterozygous--were identified in the CHST6 gene. The ELISA showed that the disease in all patients participating in the study was of MCD type I, including the subtype IA. CONCLUSIONS: These novel mutations are thought to result in loss of corneal sulfotransferase function, which would account for the MCD phenotype.

Results of photorefractive keratectomy for hyperopia using the VISX star excimer laser system.

PURPOSE: To evaluate safety, efficacy, and predictability of photorefractive keratectomy (PRK) for hyperopic astigmatism of +1.75 to 00 D manifest refractive sphere and up to -2.50 D manifest refractive astigmatism using the VISX Star excimer laser system, version 2.5 software. METHODS: Treatment was performed on 32 eyes of 21 patients. Eighteen of 21 patients were 45 years of age or older. Manifest and cycloplegic refraction together with Pelli-Robson contrast sensitivity assessment was performed prior to surgery and 1, 3, 6, 12, and 24 months after treatment. RESULTS: Twenty-seven of 32 surgical procedures were reviewed 1 year after treatment (84%). Corneal epithelial healing was complete between day 4 and 10. Twelve months after treatment, 25 of 27 eyes (93%) achieved 20/40 or better uncorrected visual acuity and 19 eyes (70%) achieved 20/20. No patient lost two or more lines of Snellen visual acuity assessed 6 months and later after treatment. The mean spherical equivalent refraction was reduced from +2.90 at baseline to +0.10 D at 1 year and +0.40 D at 2 years; 65% of eyes had a refraction within +/- 0.50 D. Four patients had further treatment by laser in situ keratomileusis for undercorrection in three eyes and overcorrection in one eye. Pelli-Robson contrast acuity was significantly reduced 12 months after treatment from a mean 1.72 before to 1.66 after PRK (P = .02, t-test). CONCLUSIONS: PRK for hyperopia using the VISX Star excimer laser system was effective in the treatment of hyperopic astigmatism. Although no patient lost two or more lines of high contrast best spectacle-corrected Snellen visual acuity 1 year after treatment, there was a significant decrease in Pelli-Robson contrast acuity.

The corneal thickness and intraocular pressure story: where are we now?

A review of the current literature was conducted regarding the effect of corneal thickness on the diagnosis of glaucoma, and the influence of excimer laser refractive surgery on intraocular pressure (IOP) measurement with Goldmann applanation tonometry. In general, normals and primary open angle glaucoma patients have a similar distribution of corneal thickness; however, there is a wide variation, ranging from 427 to 716 micro m. Normal tension glaucoma patients have a tendency towards thinner corneas than normals; however, there is an overlap of thickness measurements of more than two-thirds in 95% of patients. There is a trend for ocular hypertensives to have thicker corneas than normals, but again there is an overlap of about one-third in 95% of patients. The general trend after excimer laser refractive surgery is for a decrease in IOP, with a mean fall in IOP measured of 0.63 mmHg per dioptre correction. There is, however, a large scatter of values with some patients having the same or lower IOP post-laser, but with other patients measuring higher pressures. Corneal thickness can influence IOP measurement by Goldmann applanation tonometry; however, the magnitude of the effect is subject to much individual variation.

Acanthamoeba sclerokeratitis: treatment with systemic immunosuppression.

OBJECTIVE: This study describes the clinical features, management, and outcome of 19 patients who had severe Acanthamoeba sclerokeratitis (ASK) unresponsive to conventional management, requiring systemic immunosuppression to control disease. DESIGN: Retrospective, non-comparative, interventional case series. PARTICIPANTS: Records of all patients with Acanthamoeba keratitis treated at Moorfields Eye Hospital between 1989 and 2000 were reviewed. From more than 200 patients, 19 who developed ASK treated with systemic immunosuppression were identified. MAIN OUTCOME MEASURES: Visual acuity, level of pain, and degree of inflammation were recorded after immunosuppressive treatment. RESULTS: ASK requiring immunosuppression occurred in 20 eyes of 19 patients (11 males and 8 females). The mean age (mean +/- standard deviation) at onset was 38.6 +/- 13.2 years. On presentation, best-corrected visual acuity was counting fingers or worse in 11 eyes (55%), 6/18 to 6/60 in 5 eyes (25%), and 6/12 or better in 4 eyes (20%). The mean time between onset of initial symptoms of Acanthamoeba keratitis and commencement of systemic immunosuppression was 4.8 +/- 3.5 months. The mean duration of immunosuppression required to control inflammation was 7.2 +/- 3.9 months. Severe scleritic pain remained uncontrolled in two patients and resulted in enucleation. Best-corrected visual acuity at final follow-up was counting fingers or worse in eight eyes (40%), 6/18 to 6/60 in six eyes (30%), and 20/40 or better in six eyes (30%). The mean follow-up period after resolution of inflammation was 24.3 +/- 20.9 months (range, 0.2-59.7 months). CONCLUSIONS: ASK is an uncommon complication of Acanthamoeba keratitis. The scleritis associated with this infection seems to be an immune-mediated response. After topical amebicidal treatment, systemic immunosuppression may be required to control the pain and tissue destruction associated with ASK.