Ex vivo cultivation of corneal limbal epithelial cells in a thermoreversible polymer (Mebiol Gel) and their transplantation in rabbits: an animal model.

We evaluated the efficacy of autologous expanded corneal epithelial cell transplants derived from harvested limbal biopsy cultured on a thermoreversible polymer (Mebiol Gel) for the management of unilateral limbal stem cell deficiency (LSCD). Corneal limbal biopsies from 12 rabbits were cultured on a thermoreversible polymer Mebiol Gel at 37 degrees C. Cells were harvested from the dishes after 3 weeks by reducing temperature to 4 degrees C. Autologous transplantation was undertaken to reconstruct the experimentally induced limbal stem cell deficiency in the rabbit eyes. The corneas of both eyes of all rabbits were harvested later for molecular studies. Reparative surgery was a total success in seven rabbits, partial success in two, and failure in three eyes. Histology of the seven successful eyes showed the successful growth of the corneal epithelium. Immunohistochemistry and reverse transcriptase polymerase chain reaction showed the cornea phenotype and stem cell-associated markers in the limbus of the seven successful eyes, indicating the homing of these cells into limbus. In the three failure cases and in the two control rabbit eyes, used in the study, histology showed presence of goblet cells and vascularization in the stroma with abortive formation of corneal epithelium. Our results suggest that transplantation of autologous limbal epithelial cells grown in thermoreversible polymer Mebiol Gel may restore a nearly normal ocular epithelial surface in eyes with unilateral LSCD.

Cultivation of human corneal limbal stem cells in Mebiol gel--A thermo-reversible gelation polymer.

BACKGROUND & OBJECTIVES: Cultivated limbal stem cell transplantation is being used as a current treatment modality for limbal stem cell deficiency. However, use of allogenic biological material as substrate is associated with risks of transmission of certain diseases and allograft rejection. Therefore development of non-toxic biodegradable synthetic polymers is important. We undertook this study to evaluate the use of a synthetic polymer Mebiol gel as a substrate for the growth of limbal phenotype cells and cornea phenotype cells from limbal explants. METHODS: Human cadaveric limbal explants cells were cultivated on Mebiol gel. The proliferative capacity of cultivated cells was analyzed with thymidine incorporation studies. Immunostaining for presumed limbal stem cell association markers and cornea differentiation markers was performed and confirmed with reverse transcription (RT-PCR). RESULTS: The limbal explants underwent proliferation in vitro. The cultivated cells expressed the presumed limbal stem cell association markers (ABCG2 and p63), the transient amplifying cell markers (connexin 43, integrin alpha9) and the cornea differentiation marker (K3). RT PCR confirmed the immunohistochemical data. INTERPRETATION & CONCLUSION: Our findings showed that the synthetic polymer Mebiol gel was able to support limbal explant proliferation. The cultured cells expressed presumed limbal stem cell association markers, transient amplifying cells and cornea phenotype markers. Mebiol Gel can be used as a scaffold for growing limbal explants.

Cystoid macular edema after pediatric intraocular lens implantation: fluorescein angioscopy results and literature review.

PURPOSE: To evaluate the occurrence of cystoid macular edema (CME) after lens extraction, anterior vitrectomy, and intraocular lens implantation (IOL) in children using angioscopy after administration of oral fluorescein. SETTING: Centers in Tamil Nadu, India, and Hong Kong, China. METHODS: This study comprised 18 children (28 eyes) who had cataract extraction, posterior capsulorhexis, anterior vitrectomy, and in-the-bag IOL implantation. The presence of CME was evaluated 1 week and 4 to 6 weeks after surgery using fluorescein angioscopy. RESULTS: Anterior chamber fibrin occurred in 4 eyes (14.3%). Fluorescein angioscopy was performed 1 week after surgery in all eyes and after 1 month in 25 eyes (89.3%). No eye demonstrated the presence of CME on fluorescein angioscopy. CONCLUSIONS: Cystoid macular edema did not occur in the early period after pediatric cataract surgery using current surgical techniques. Longer follow-up is required to ascertain the incidence of CME in the late postoperative period.

Fellow eye treatment in excimer photo refractive keratectomy.

PURPOSE: To describe symmetry of response in fellow eyes of patients undergoing photorefractive keratectomy (PRK) for myopia, analyse the risk factors leading to asymmetry in response and to determine if delayed treatment of the second eye increases safety and predictability of PRK. METHODS: Retrospective review of case records of 133 patients who underwent bilateral myopic PRK and had a minimum follow up of 6 months in both eyes. RESULTS: Postoperative uncorrected visual acuity, spherical equivalent (SE) refraction within +/- 1 D of emmetropia, best-corrected visual acuity (BCVA) and corneal haze were not significantly different in fellow eyes of patients undergoing PRK for myopia. Of 87 eyes in group 1 (myopia < 6 D), 96.6% had uncorrected visual acuity > or = 6/12, 89.7% were within +/- 1 D of emmetropia, none lost > or = 1 line BCVA, and none had haze > or = grade 3. Similar results for 98 eyes in group II (myopia 6 to 9.9 D) were 75.6%, 55.1%, 2.0% and 2.0% respectively. For 81 eyes in group III (myopia > or = 10 D) the results were 42.7%, 33.3%, 8.6%, and 4.9% respectively. Among 84 patients with similar preoperative myopia in both eyes, 54 (64.3%) patients had a postoperative SE difference < or = 1 D in fellow eyes. Risk factors for asymmetric response among fellow eyes included increasing preoperative myopia (p < 0.001) and dissimilar treatment technique in the two eyes (p = 0.03). Corneal haze did not increase significantly after the third postoperative month. CONCLUSION: This study demonstrates that considerable symmetry of response exists in fellow eyes of patients undergoing myopic PRK. Early PRK in the fellow eye of patients with < 6 D myopia is safe and allows quick visual rehabilitation of the patient. In patients with myopia > or = 6 D, a 3-month interval before treating the second eye may improve the safety of the procedure.

Corneal autografting: a systematic approach.

OBJECTIVE: To describe a systematic approach to corneal autografting. PATIENTS AND METHODS: Retrospective review of case records of 3 patients who underwent this procedure. RESULTS: All patients achieved satisfactory visual recovery. Oversized grafts of 0.5 mm had less post-operative complications in the recipient eye. A phakic blind eye that received a 0.5 mm undersized graft had a temporary ocular hypertensive phase. CONCLUSIONS: Corneal autografting is a safe and effective technique in selected patients. The preferred surgical technique consists of surgery first on the blind eye, excision of a 0.5 mm oversized donor graft, cataract extraction if the eye is phakic, and use of an appropriate temporary keratoprosthesis to maintain donor eye integrity until autografting is completed in the eye with visual potential.

Bilateral corneal infiltrates after excimer laser photorefractive keratectomy.

A 26-year-old man developed painless inferior subepithelial infiltrates away from the site of ablation in both eyes after excimer laser photorefractive keratectomy (PRK) for myopia. Clinical characteristics of the corneal infiltrates resembled staphylococcal-immune infiltrates. The condition responded to treatment with topical diluted steroids and antibiotics. There was no residual corneal scarring. The infiltrates did not affect the refractive outcome of the surgery. Recognition of this rare entity will help clinicians avoid aggressive investigative and treatment modalities that can affect the results of PRK.

Partial flap during laser in-situ keratomileusis: pathogenesis and timing of retreatment.

PURPOSE: To report the timing of retreatment and clinical outcomes in patients with a partial corneal flap during laser in-situ keratomileusis (LASIK), and to describe the causes of this complication. METHODS: Retrospective review of case records of four patients (4 eyes) who had a partial corneal flap during LASIK. RESULTS: The mean age of the four patients was 23 +/- 4.7 years, and mean preoperative spherical equivalent (SE) refraction was -9.1 +/- 3.1 D (range, -5.5 to -13 D). A 160 microns corneal flap was attempted during the initial treatment. Retreatment with a 180 microns corneal flap was performed at a mean of 5.1 +/- 1.6 weeks (range, 4 to 7.5 weeks) after the initial procedure. There were no intraoperative complications during retreatment. Post-LASIK mean SE refraction was -1.0 +/- 1.1 D (range, +0.38 to -2.0 D), after a mean follow up of 19 +/- 15.7 weeks (range, 7 to 42 weeks). Best spectacle-corrected visual acuity decreased in one eye from 6/5 to 6/6 and was maintained in the others. CONCLUSION: LASIK retreatment can be performed as early as one month after a partial flap, if the refraction is stable and a thicker corneal flap is created.

Nocardia Asteroides keratitis: report of seven patients and literature review.

PURPOSE: To describe clinical features and treatment outcomes in patients with advanced Nocardia asteroides keratitis. METHODS: Retrospective review of case records of 7 patients with culture-proven Nocardia keratitis. RESULTS: Corneal infection occurred after corneal trauma in two patients, cataract surgery in three patients, penetrating keratoplasty in one patient and was associated with a silicone buckle element infection in one patient. Mean duration of infection at presentation was 33.4 days (7-75 days), and five patients had received prior treatment with corticosteroids. Six of seven patients had deep corneal suppuration at the time of presentation, clinically suggestive of mycotic keratitis. In two patients who had received prolonged corticosteroid therapy (> or = 45 days), the eyes could not be salvaged. Complete resolution of infection was achieved in all 4 eyes treated with topical fortified cefazolin eye drops (50 mg/ml).

Corneal topography in atypical pellucid marginal degeneration.

PURPOSE: Pellucid marginal degeneration (PMD) is commonly described as a noninflammatory corneal ectasia typically involving the inferior cornea. Although reports of superior corneal changes in PMD exist, the topographic patterns of these PMD variants are not well characterized. We describe corneal topographic alterations seen in eyes with atypical PMD. METHODS: Computer-assisted videokeratography was performed in 10 eyes of five patients with PMD. RESULTS: Eight of the eyes studied had changes involving the superior cornea, with or without changes in the inferior cornea. Atypical presentations of PMD included extension of inferior peripheral thinning above the horizontal meridian and occurrence of superior corneal thinning and ectasia with or without typical inferior changes. Atypical PMD reveals topographic patterns similar to classic PMD, but corneal changes also involve the nasal, temporal, or superior quadrants or a combination of these. The topographic maps reflect the location of peripheral corneal thinning and extent of corneal protrusion. CONCLUSIONS: Corneal topographic changes in atypical PMD are similar to those seen in typical PMD but can involve the superior cornea.

Limbal allografting from related live donors for corneal surface reconstruction.

OBJECTIVE: To report the results of limbal allograft transplantation, from human leukocyte antigen (HLA)-matched and -unmatched related live donors, in patients with ocular surface disease due to chemical burns and Stevens-Johnson syndrome. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: Eight patients (nine eyes) with severe chemical burns (n = 7 eyes) and Stevens-Johnson syndrome (n = 2 eyes). INTERVENTION: Recipient eyes were treated with excision of cicatricial tissues. Transplantation of superior and inferior limbal grafts was performed from related live HLA-matched (n = 7) and -unmatched donors (n = 2). Systemic cyclosporine was not used in any of the recipients. MAIN OUTCOME MEASURES: Reconstruction of corneal surface epithelium, restoration of avascularity, increase in ocular comfort, and improvement in visual acuity. RESULTS: With a mean observation period of 17.2 months, phenotypically corneal epithelium, decreased vascularization of the corneal surface, and improved ocular comfort were seen in seven (77.8%) eyes. In all seven eyes, gradual recurrence of peripheral corneal vascularization occurred during the follow-up period. Features of graft rejection developed in three (42.9%) of these seven eyes. In two eyes, limbal transplantation from HLA-unmatched donors failed to reconstitute the corneal surface. Limbal allograft transplantation resulted in visual acuity of 20/400 or greater in only two (22.2%) eyes at last follow-up. Corneal grafts performed 7 and 16 months after successful limbal transplantation in two eyes developed recurrent epithelial breakdown and superficial corneal scarring. None of the donor eyes in this study had any complication. CONCLUSION: Transplantation of limbal tissue from related live donors successfully reconstructs the corneal surface in HLA-matched recipients. Recurrence of vascularization on long-term follow-up probably results from inadequate stem cell transfer, immune-mediated stem cell damage, or both. Limbal allografting is best performed by transplanting the entire limbus from a cadaveric donor eye with systemic immunosuppression of the recipient, even if the donor is HLA-compatible.

Limbal autografting: comparison of results in the acute and chronic phases of ocular surface burns.

PURPOSE: To compare outcomes of limbal autograft transplantation (LAT) in the acute and chronic phases of ocular surface burns. METHODS: Retrospective analysis of case records of 16 consecutive patients who underwent LAT for ocular surface burns, at our institute, between April 1994 and March 1997. RESULTS: Limbal autograft transplantation was successful in reconstructing the corneal surface and restoring ocular comfort in 15 (93.8%) eyes. Limbal autografting failed to reconstruct the ocular surface in one patient undergoing surgery 2 weeks after grade IV alkali burns. In 13 eyes with counting fingers or worse vision, functional success (visual acuity >20/400) was attained after LAT in nine (69.2%) eyes. Visual acuity > or = 20/80 was achieved in two (25%) of eight eyes undergoing surgery for a persistent epithelial defect (PED) and five of six (83.3%) eyes undergoing surgery after the epithelial defect had healed (p = 0.03). Nine patients underwent simultaneous superior and inferior limbal autografting. Mean epithelial healing time in six of these patients undergoing surgery in the acute phase of injury (<4 months) was 15+/-6.1 days. In three patients undergoing a similar procedure in the chronic phase of injury, the healing time was 8.3+/-6.7 days. CONCLUSIONS: Limbal autograft transplantation is successful in reconstructing the corneal surface and restoring ocular comfort after ocular surface burns. Surgery in the acute phase of injury (<4 months), in the presence of a PED, could result in delayed corneal reepithelialization and poorer visual prognosis. If performed in the acute phase of injury, LAT should be performed after adequate limbal vascularization and resolution of surface inflammation in the recipient eye, avoiding graft placement over ischemic limbus.

Bilateral penetrating keratoplasty--indications, results and review of literature.

PURPOSE: To analyze the indications, functional results, and rates of graft rejection and failure after bilateral penetrating keratoplasty (PK) in a major eye care hospital and research center in India. METHODS: Retrospective review of the case records of 38 patients who underwent bilateral PK and had at least 6 months follow-up after corneal transplantation in the second eye. RESULTS: The mean age of the 38 patients (20 M, 18 F) was 35 +/- 25 years (range, 0.5 to 79 years). Mean follow-up was 49 +/- 23 months (range, 13.4 to 116.4 months) after surgery in the first eye and 31 +/- 22 months (range, 6.6 to 103.6 months) after surgery in the second eye. The average time interval between surgery in the first and second eye was 18 +/- 10 months (range, 0 to 38 months). The commonest indications for surgery were corneal dystrophies (50%), aphakic bullous keratopathy (21%), and keratoconus (11%). Postoperatively, secondary glaucoma occurred in 2 first and 3 second eyes. Best-corrected visual acuity at last follow-up was > 6/12 in 34% of first eyes and 50% of second eyes, and was < 6/60 in 26% and 18% of first and second eyes respectively. Allograft rejection occurred in 4 of the first eyes and 3 of the second eyes. The two-year graft survival rate in first eyes was 70% and in second eyes was 83%. Worse outcomes were noted in grafts performed for secondary endothelial failure. Earlier graft failure occurred in first eyes (54 +/- 5 months) compared to second eyes (79 +/- 10 months) (Logrank Test p = 0.2311). CONCLUSIONS: Bilateral penetrating keratoplasty has reasonable success in selected patients. Corneal transplantation in the second eye does not seem to increase the risk of graft rejection in either eye.

Ligneous conjunctivitis: a clinicopathologic study of 3 cases.

The clinical, histopathologic features, and treatment outcomes in 3 patients with ligneous conjunctivitis are described. Bilateral, idiopathic membranes occurred in the palpebral conjunctiva in 2 patients. In 1 patient, unilateral conjunctival changes occurred in the bulbar conjunctiva, at the site of pterygium excision. Treatment included topical hyaluronidase, chymotrypsin, heparin, and cyclosporine and surgical excision with limited or no success. In one patient, conjunctival autografting from the normal fellow eye resulted in pseudomembrane formation at the donor site in the previously unaffected eye. Histopathological evaluation of excised membranes revealed the presence of amorphous eosinophilic hyaline material and chronic inflammatory cells. Immunohistochemical study revealed a predominance of T-lymphocytes. This case series confirms the recalcitrant clinical course of ligneous conjunctivitis. Conventional treatment modalities described in literature were not useful in the management of this condition. Surgical manipulation of the unaffected fellow eye in patients with unilateral disease can result in pathologic conjunctival changes, and is best avoided.

Conjunctival-limbal autografts for primary and recurrent pterygia: technique and results.

Our technique of pterygium excision with conjunctival-limbal autografting is described and the safety and efficacy of the procedure in India is analysed. Case records of 51 consecutive patients (53 eyes) who underwent surgery at our institute between November 1992 and September 1994 were retrospectively analysed. Recurrence was defined as fibrovascular tissue crossing the corneoscleral limbus onto clear cornea in the area of previous pterygium excision. 2 (3.8%) of the 53 pterygia (primary 36; recurrent 17) recurred, after a mean follow up of 18.9 +/- 12.1 months (range: 1.5-43 months). Both recurrences occurred within a year of follow up, in patients who were < or = 40 years of age. No major operative or postoperative complications were encountered. The inclusion of limbal tissue in conjunctival autografts following pterygium excision appears to be essential to ensure low recurrence rates. The technique is safe, simple and inexpensive and is recommended for the management of both primary and recurrent pterygia in Indian eyes.

Photorefractive keratectomy: the Sankara Nethralaya experience.

BACKGROUND AND OBJECTIVE: Excimer laser photorefractive keratectomy (PRK) is quickly establishing itself as a dependable treatment modality for the correction of myopia. We review in this report our experience with the Summit OmniMed UV200 excimer laser (Summit Technology, Inc., Waltham, MA) in the treatment of low to high degrees of myopia. PATIENTS AND METHODS: We retrospectively analyzed the results of excimer laser PRK in 139 eyes of 127 patients treated between November 1993 and August 1994. RESULTS: The study population was comprised of 75 males and 52 females with a mean ago of 26.9 +/- 6.21 years (range, 19 to 52 years). All patients were followed for at least six months and the mean follow-up was 11.7 +/- 3.63 months (range, 6 to 22 months). Mean pre-operative myopia was -8.23 +/- 3.32 diopters (D) (-2.63 to -19.50 D). Of 139 eyes, 101 (72.7%) had a pre-operative myopia greater than -6.00 D; and 32 (23.0%) had a pre-operative myopia greater than -10.00 D. At last follow-up, 73 (52.5%) eyes were within +/-1.00 D of emmetropia, 92 (66.2%) eyes had an uncorrected visual acuity of > or = 6/12, and 12 (8.6%) eyes lost 2 or more lines of spectacle corrected visual acuity. Severe corneal haze (grade 3 to 4) was seen in 20 (14.4%) eyes at last follow-up. Complications encountered in this series included steroid response in 15 (10.8%) eyes, and reactivation of herpes simplex keratitis in one (0.7%) eye. Statistical analysis reveals that the only risk factor independently associated with regression > or = 2.00 D following PRK is the occurrence of severe corneal haze (grade 3 and 4). CONCLUSION: Excimer laser PRK appears to be a safe and predictable method for the treatment of myopia < 6.00 D. With higher degrees of myopia the results appeared to be more guarded, mainly due to the healing pattern of the cornea following single zone myopic ablations.