Balasubramanya Ramamurthy

Autosomal recessive corneal endothelial dystrophy (CHED2) is associated with mutations in SLC4A11

Objective: To map and identify the gene for autosomal recessive congenital hereditary endothelial dystrophy (CHED2, OMIM 217700), a disorder characterised by diffuse bilateral corneal clouding that may lead to visual impairment and requiring corneal transplantation. Methods: Members of 16 families with autosomal recessive CHED were genotyped for 13 microsatellite markers at the CHED2 locus on chromosome 20p13-12. Two-point linkage analysis was carried out using the FASTLINK version of the MLINK program. Mutation screening was carried out by amplification of exons and flanking regions by polymerase chain reaction, followed by direct automated sequencing. Results: Linkage and haplotype analysis placed the disease locus within a 2.2 cM (1.3 Mb) interval flanked by D20S198 and D20S889, including SLC4A11. The maximum limit of detection score of 11.1 was obtained with D20S117 at θ = 0. Sequencing of SLC4A11 showed homozygotic mutations in affected members from 12 of 16 families. Conclusion: These results confirm that mutations in the SLC4A11 gene cause autosomal recessive CHED.

Mutation of the gap junction protein alpha 8 (GJA8) gene causes autosomal recessive cataract

Background:GJA8 encodes connexin-50, a gap junction protein in the eye lens. Mutations in GJA8 have been reported in families with autosomal dominant cataract. Objective: To identify the disease gene in a family with congenital cataract of autosomal recessive inheritance. Methods: Eight candidate genes were screened for pathogenic alterations in affected and unaffected family members and in normal unrelated controls. Results: A single base insertion leading to frameshift at codon 203 of connexin 50 was found to co-segregate with disease in the family. Conclusions: These results confirm involvement of GJA8 in autosomal recessive cataract.

Outcome of corneal transplant rejection: a 10‐year study

Purpose:  To study the incidence of graft rejection and the predictive factors for its reversibility.

Surgical and visual outcomes for posterior polar cataract

Aims: The aims of this study were to report the surgical and visual outcomes of posterior polar cataract and to assess the risk factors for posterior capsule rupture. Method: Medical records of 81 eyes of 59 patients were reviewed. The surgical procedure used, intraoperative complications and postoperative visual outcome were recorded. Results: Of the 81 eyes, 61 eyes (75%) underwent phacoemulsification. Seventeen eyes had extra-capsular cataract extraction, and manual small incision cataract surgery was performed on three eyes. Posterior capsule rupture occurred in 25 (31%) eyes: it was more common in young patients (<40 years) and in the extra-capsular cataract extraction group. Two eyes had nucleus drop during phacoemulsification. The postoperative visual acuity was ⩾20/30 in 76 eyes. Conclusion: Posterior capsule rupture occurred more frequently in extra-capsular cataract extraction compared with phacoemulsification and in patients below 40 years of age. Phacoemulsification, done carefully, leads to good visual outcome.

Deep lamellar keratoplasty in keratoconus with healed hydrops.

Purpose: To report a case of successful deep lamellar keratoplasty (DLK) in a patient with keratonous after healed hydrops. Methods: A 17-year-old boy underwent DLK for corneal scar secondary to healed hydrops in a case of keratoconus. Results: The graft was clear, with a postoperative best spectacle-corrected visual acuity of 20/20. Conclusions: DLK may be a viable option in healed hydrops.

Ultrastructural analysis of damage to nuclear fiber cell membranes in advanced age-related cataracts from India.

The primary goal was to characterize the structural alterations that occur at the fiber cell interfaces in nuclei of fully opaque cataracts removed by extracapsular cataract surgery in India. The dark yellow to brunescent nuclei, ages 38-78 years, were probably representative of advanced age-related nuclear cataracts. Thick tissue slices were fixed, en bloc stained and embedded for transmission electron microscopy. Stained thin sections contained well-preserved membranes and junctions, although the complex cellular topology often made it necessary to tilt the grid extensively to visualize the membranes. Damage to the fiber cell membranes was noted in all regions of the nucleus. The most important damage occurred within undulating membrane junctions where the loss of membrane segments was common. These membrane breaks were not sites of fusion as membrane edges were detected and cytoplasm appeared to be in contact with extracellular space, which was enlarged in many regions. Dense deposits of protein-like material were frequently observed within the extracellular space and appeared to be similar to protein in the adjacent cytoplasm. The deposits were often 20-50 nm thick, variable in length and located on specific sites on plasma membranes and between clusters of cells or cell processes. In addition, low density regions were seen within the extracellular space, especially within highly undulating membranes where spaces about 100 nm in diameter were observed. The membrane damage was more extensive and extracellular spaces were larger than in aged transparent donor lenses. Because high and low density regions contribute equally to the fluctuations in refractive index, the changes in density due to the observed damage near membranes are likely to produce significant light scattering based on theoretical analysis. The dimensions of the fluctuations in the range 20-100 nm imply that the scattering is probably similar to that of small particles that would increase high-angle scattering visible in the slit lamp. Such damage to membranes would be expected to contribute to the total opacification of the nucleus as the cataract matures. The main sources of the fluctuations appear to be the degradation of membranes and adjacent cytoplasmic proteins, as well as the redistribution of proteins and fragments.

Analysis of nuclear fiber cell cytoplasmic texture in advanced cataractous lenses from Indian subjects using Debye-Bueche theory.

Alterations in ultrastructural features of the lens fiber cells lead to scattering and opacity typical of cataracts. The organelle-free cytoplasm of the lens nuclear fiber cell is one such component that contains vital information about the packing and organization of crystallins critical to lens transparency. The current work has extended analysis of the cytoplasmic texture to transparent and advanced cataractous lenses from India and related the extent of texturing to the nuclear scattering observed using the Debye-Bueche theory for inhomogeneous materials. Advanced age-related nuclear cataracts (age-range 38-75 years) and transparent lenses (age-range 48-78 years) were obtained following extracapsular cataract removal or from the eye bank, at the L.V. Prasad Eye Institute. Lens nuclei were Vibratome-sectioned, fixed and prepared for transmission electron microscopy using established techniques. Electron micrographs of the unstained thin sections of the cytoplasm were acquired at 6500x and percent scattering for wavelengths 400-700 nm was calculated using the Debye-Bueche theory. Electron micrographs from comparable areas in an oxidative-damage sensitive (OXYS) rat model and normal rat lenses preserved from an earlier study were used, as they have extremely textured and smooth cytoplasms, respectively. The Debye-Bueche theoretical approach produces plots that vary smoothly with wavelength and are sensitive to spatial fluctuations in density. The central lens fiber cells from advanced cataractous lenses from India and the OXYS rat, representing opaque lens nuclei, produced the greatest texture and scattering. The transparent human lenses from India had a smoother texture and less predicted scattering, similar to early cataracts from previous studies. The normal rat lens had a homogeneous cytoplasm and little scattering. The data indicate that this method allowed easy comparison of small variations in cytoplasmic texture and robustly detected differences between transparent and advanced cataractous human lenses. This may relate directly to the proportion of opacification contributed by the packing of crystallins. The percent scattering calculated using this method may thus be used to generate a range of curves with which to compare and quantify the relative contribution of the packing of crystallins to the loss of transparency and scattering observed.

A cluster of Nocardia keratitis after LASIK.

PURPOSE To report a cluster of Nocardia asteroides keratitis cases after LASIK. METHODS Retrospective review of the history and examination of three patients (four eyes) operated on the same day at a single center who developed postoperative keratitis. All patients underwent lifting of the superficial flap for microbiologic evaluation of the corneal scrapings. The operating surgeon was contacted to identify the possible source of contamination. RESULTS Two patients underwent simultaneous bilateral LASIK; however, only one developed postoperative keratitis in both eyes. One patient had unilateral surgery and developed keratitis in the operated eye. Microscopic examination of smears from all eyes revealed thin, branching, acid-fast, filamentous bacteria that were identified as Nocardia asteroides after culture. The infiltrates resolved with topical administration of amikacin sulphate (2.5%) and topical and oral trimethoprim-sulfamethoxazole. Final visual acuity ranged between 20/25 and 20/80. The operating surgeon had used the same blade and microkeratome in all patients. CONCLUSIONS Nocardia, a relatively unusual organism, can cause an epidemic of infection after LASIK.

Coexistent congenital hereditary endothelial dystrophy and congenital glaucoma.

Purpose: To retrospectively evaluate the coexistence of congenital glaucoma with congenital hereditary endothelial dystrophy. Methods: Ten infants presented to our hospital with diffuse corneal edema and bilaterally elevated intraocular pressure (IOP). These patients were diagnosed with congenital glaucoma. All patients underwent trabeculotomy with trabeculectomy for control of IOP. Although IOP was normalized in all patients, corneal edema persisted. These patients underwent penetrating keratoplasty, and the buttons were subjected to histopathologic examination. Results: The corneal grafts remained clear in all patients. The histopathologic examination of the excised corneal buttons showed diffuse stromal edema, loss of the endothelial cell layer, and thickening of the posterior nonbanded portion of the Descemet membrane, suggestive of congenital hereditary endothelial dystrophy. Conclusions: Congenital hereditary endothelial dystrophy may coexist with congenital glaucoma. This combination should be suspected where persistent and total corneal opacification fails to resolve after normalization of IOP.

Deep Lamellar Keratoplasty for Recurrent Advanced Pterygium

The authors report a case of recurrent advanced pterygium managed by deep lamellar keratoplasty and conjunctival autograft. A woman presented with bilateral recurrent advanced pterygium (more prevalent in the left eye) associated with corneal thinning in the left eye. Two-thirds of the cornea was covered by pterygia. Her visual acuity was counting fingers at 1 meter in the right eye and light perception with projection of rays being accurate in all quadrants in the left eye. She underwent deep anterior lamellar keratoplasty and conjunctival autograft in her left eye. Clarity, state of corneal graft, and postoperative visual acuity were noted. The graft was clear and the patients best-corrected visual acuity improved to 20/60 after the surgery. Deep lamellar keratoplasty with conjunctival autograft is a good option as a single-stage surgery for recurrent advanced pterygium.