Diagnostic utility of in vivo confocal microscopy in Acanthamoeba keratitis following corneal crosslinking.

Acanthamoeba keratitis (AK) is a rare but potentially sight-threatening complication of corneal collagen crosslinking (CXL) for keratoconus. In this report, we describe an early adolescent male who underwent routine CXL for progressive keratoconus in his left eye. Preprocedural left visual acuity (VA) was 6/9. At day 5 postprocedure, multifocal corneal infiltrates were identified. Corneal scrape, bandage contact lens cultures and herpetic and Acanthamoeba PCR were negative. In vivo, confocal microscopy (IVCM) identified Acanthamoeba cysts within the corneal stroma. Intensive amoebicidal therapy was initiated, but recovery was complicated by significant inflammation, resulting in widespread aggressive corneal vascularisation necessitating topical steroids and steroid-sparing agents. At 10 months, his left VA was 6/24. This report emphasises the importance of maintaining a high index of suspicion for AK in cases of post-CXL microbial keratitis and highlights the diagnostic value of IVCM, particularly in culture-negative and PCR-negative cases.

Exome-based mutation screening in South African children with primary congenital glaucoma.

OBJECTIVES: To identify pathogenic variants in a cohort of 23 black South African children with sporadic primary congenital glaucoma (PCG) using an exome-based approach. METHODS: Children with PCG were recruited from two Paediatric Ophthalmology Clinics in Johannesburg, South Africa. Whole exome sequencing was performed on genomic DNA. Of the 23 children, 19 were male and 19 had bilateral PCG. A variant prioritization strategy was employed whereby variants in known PCG genes (CYP1B1, LTBP2 and TEK) were evaluated first, followed by the identification of putative disease-causing variants in other genes related to eye diseases and phenotypes. RESULTS: Validated pathogenic variants in the CYP1B1 gene (c.1169 G>A; p.Arg390His) and TEK gene (c.922 G>A; p.Gly308Arg) were identified in one child each. No LTBP2 mutations were identified in this cohort. In silico predictions identified potentially damaging rare variants in genes previously associated with eye development phenotypes or glaucoma in a further 12 children. CONCLUSIONS: This study demonstrates the value of whole exome sequencing in identifying disease-causing variants in African children with PCG. It is the first report of a TEK disease-causing variant in an African PCG patient. Potential causative variants detected in PCG candidate genes warrant further investigation.

Medium-Term Failure of Descemet's Stripping Only and Fuchs' Dystrophy With Pancorneal Guttae.

PURPOSE: The purpose of this study was to report the medium-term outcome of our index case of Descemet stripping only (DSO) in the clinical setting of Fuchs endothelial corneal dystrophy with pancorneal guttae. METHODS: This was a retrospective case report. RESULTS: A 44-year-old woman with bilateral Fuchs endothelial corneal dystrophy was referred for consideration of DSO. At initial slit-lamp examination, widespread guttae were observed with no clear zone visible. Confocal microscopic examination also failed to isolate a population of undisturbed endothelial cells. DSO with supplemental ripasudil was performed with corneal clearance achieved at 2.5 months. A stable result was obtained for 18 months with a subsequent slow decline in vision and return of diurnal fluctuation. At 3.5 years after DSO, DMEK was performed with resolution of symptoms. CONCLUSIONS: Medium-term failure in this clinical setting is further evidence that DSO is likely best offered to patients with central guttae but a clear corneal periphery, indicative of a healthy cell reservoir.

Case Report: Use of Amniotic Membrane for Tectonic Repair of Peripheral Ulcerative Keratitis With Corneal Perforation.

Purpose: To provide a perspective and surgical video demonstration of peripheral corneal ulceration and perforation managed with multilayered amniotic membrane transplantation. Case Reports: Case 1 describes a 48-year-old female with progressive redness and pain, and an inferonasal corneal thinning and perforation in the left eye from peripheral ulcerative keratitis. She underwent conjunctival recession with amniotic membrane inlay and onlay (Sandwich technique) transplantation. The amniotic membrane integrated well, and her Snellen visual acuity improved from 6/21 preoperatively to 6/9 at 3 months post op. Case 2 describes a 78-year-old male with redness and pain with temporal corneal thinning bilaterally and perforation in the right eye from peripheral ulcerative keratitis. Both eyes underwent similar surgical intervention with smooth integration of the amniotic membrane in the cornea and improvement in the visual acuity. Both patients were also started on systemic immunosuppression in collaboration with the rheumatology team. Conclusion: We report successful use of multilayered amniotic membrane transplantation for the treatment of corneal ulceration and perforation. The authors believe the simplicity of the surgical technique, easier access to amniotic membrane tissue, and lower induced post-operative astigmatism all provide advantages over alternative treatment modalities.

Familial congenital cataract, coloboma, and nystagmus phenotype with variable expression caused by mutation in PAX6 in a South African family.

Purpose: To report on a clinical and genetic investigation of a large, multigenerational South African family of mixed ancestry with autosomal dominant congenital cataracts, coloboma, and nystagmus. Methods: Ophthalmic examination was performed in 27 individuals from the same admixed South African family. DNA was sampled from either peripheral blood or buccal swabs in all 27 individuals, and whole genome sequencing was performed in six individuals. Sanger sequencing was used to validate the probable mutation in the remaining family members. Results: Twenty-seven family members with 19 affected individuals were included in the study. The predominant phenotype, with highly variable expression, was congenital cataract (14 individuals), posterior segment coloboma (17 individuals), and nystagmus (18 individuals). Other features present included high myopia, microcornea, and strabismus. An R208W mutation in PAX6 (dbSNP rs757259413; HGMD CM930572; NM_000280.3:c.622G>A; NP_000271.1:p.Arg208Trp) was identified as being the most probable pathogenic mutation. Cosegregation of the mutation with the phenotype was confirmed in all 27 family members. Conclusions: PAX6 is a highly conserved gene crucial for normal oculogenesis, and although mutations within the gene may cause an array of ocular developmental abnormalities, most are associated with aniridia and aniridia-related ocular defects. The observation that PAX6 aniridia phenotypes are largely associated with nonsense mutations and milder non-aniridia phenotypes with missense mutations suggested that there may be specific genotype-phenotype correlations for the gene. The R208W mutation in PAX6 identified in this family challenges this theory as it has previously been reported in three unrelated families and is associated with aniridia and non-aniridia phenotypes across the four families. PAX6 with its wide phenotypic associations and highly variable expression should be considered a candidate gene in the diagnostic screen for any ocular developmental abnormality.

A 20-Year Retrospective Review of Retinoblastoma at Two Tertiary Academic Hospitals in Johannesburg, South Africa.

AIM: This paper presents a 20-year review of retinoblastoma in Johannesburg, South Africa, aiming to better characterize the disease in this sub-Saharan setting. METHODS: The study represents a retrospective case series of retinoblastoma patients presenting to Charlotte Maxeke Johannesburg Academic Hospital and Chris Hani Baragwanath Academic Hospital between January 1, 1992, and December 31, 2011. RESULTS: The total number of cases identified was 282, with 245 meeting the study inclusion criteria. Retinoblastoma comprised 6.9% of the total pediatric oncology presentations; 65.3% were unilateral, 34.3% bilateral, and 0.4% trilateral. The overall male-to-female ratio was 1.08. The mean age at presentation overall was 32.6 months (median 28.0), in the unilateral group 39.4 months (median 33.0), and in the bilateral group 19.7 months (median 17.0). The mean delay to presentation overall was 7.0 months (median 4.0). The most frequent presenting symptoms were leukocoria (37.1%) and proptosis (34.7%). The distribution of disease stages at presentation (International Retinoblastoma Staging System) was 1.6% stage 0, 24.1% stage I, 27.8% stage II, 16.3% stage III, and 25.3% stage IV. 26.5% defaulted care. The 5-year Kaplan-Meier survival estimate was 57.7% overall. CONCLUSION: This study shows that delayed presentation and refusal of therapy remains a significant barrier to effective treatment in this African setting.

Novel mutation in the CHST6 gene causes macular corneal dystrophy in a black South African family.

BACKGROUND: Macular corneal dystrophy (MCD) is a rare autosomal recessive disorder that is characterized by progressive corneal opacity that starts in early childhood and ultimately progresses to blindness in early adulthood. The aim of this study was to identify the cause of MCD in a black South African family with two affected sisters. METHODS: A multigenerational South African Sotho-speaking family with type I MCD was studied using whole exome sequencing. Variant filtering to identify the MCD-causal mutation included the disease inheritance pattern, variant minor allele frequency and potential functional impact. RESULTS: Ophthalmologic evaluation of the cases revealed a typical MCD phenotype and none of the other family members were affected. An average of 127 713 variants per individual was identified following exome sequencing and approximately 1.2 % were not present in any of the investigated public databases. Variant filtering identified a homozygous E71Q mutation in CHST6, a known MCD-causing gene encoding corneal N-acetyl glucosamine-6-O-sulfotransferase. This E71Q mutation results in a non-conservative amino acid change in a highly conserved functional domain of the human CHST6 that is essential for enzyme activity. CONCLUSION: We identified a novel E71Q mutation in CHST6 as the MCD-causal mutation in a black South African family with type I MCD. This is the first description of MCD in a black Sub-Saharan African family and therefore contributes valuable insights into the genetic aetiology of this disease, while improving genetic counselling for this and potentially other MCD families.