Conjunctival-limbal autografts for primary and recurrent pterygia: technique and results. (1/345)

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.  (+info)

Expression of cell adhesion molecules on limbal and neovascular endothelium in corneal inflammatory neovascularization. (2/345)

PURPOSE: To investigate the expression of cell-adhesion molecules on corneolimbal and neovascular endothelium and the associated leukocyte infiltration in an experimental model of inflammatory corneal neovascularization (NV). METHODS: Corneal NV was induced in BALB/c mice by placement of nylon sutures. Interleukin-1 receptor antagonist (IL-1ra) was used topically to determine whether suppression of IL-1 could affect adhesion molecule expression and leukocytic infiltration. At set time points, corneal samples were analyzed immunohistochemically for expression of P-selectin, E-selectin, intercellular adhesion molecule (ICAM)-1, vascular adhesion molecule (VCAM)-1, and platelet- endothelial adhesion molecule (PECAM)-1. Leukocytic infiltration at different time points was quantified histologically. In companion experiments mice deficient in ICAM-1 were investigated to determine the functional relevance of this molecule in corneal leukocyte infiltration. RESULTS: Significant enhanced expression of ICAM-1 was detected on the corneolimbal vascular endothelium as early as 8 hours and on the newly formed corneal NV by day 3, and treatment with IL-1ra led to significant suppression of this expression. IL-1ra-induced suppression of ICAM-1 expression was accompanied by a profound decrease in corneal leukocytic infiltration by 44.6% at day 1 (P < 0.003), 71.8% at day 3 (P < 0.001), 60.1% at day 7 (P < 0.001), and 63.8% at day 14 (P < 0.001), compared with control corneas. Similarly, in ICAM-1 knockout mice, the corneal leukocytic infiltration was 50.3%, 52.9%, and 36.4%, compared with wild-type control animals on day 1 (P < 0.001), day 7 (P < 0.005), and day 14 (P < 0.001), respectively. Expression of PECAM-1 was constitutively present on perilimbal vascular endothelium and had no response to IL-1ra treatment. No significant expression of P-selectin, E-selectin, or VCAM-1 was detected in this experimental model. CONCLUSIONS: These results suggest that leukocytic infiltration in this model of inflammatory corneal NV is closely associated with ICAM-1 expression, and that topical IL-1ra displays corneal anti-inflammatory effects, largely by suppressing ICAM-1 expression on vascular endothelial cells.  (+info)

Evidence of long-term survival of donor-derived cells after limbal allograft transplantation. (3/345)

PURPOSE: Severe destruction of the corneal limbus causes conjunctival invasion and subsequent visual loss. Limbal allograft transplantation (LAT) was recently proposed for the treatment of these disorders. However, whether the method functions as a stem cell transplantation of the corneal epithelium remains unclear. This study provided evidence that donor-derived corneal epithelial cells survive long after LAT. METHODS: Epithelial cells on the paracentral cornea in patients who have undergone LAT were subjected to fluorescence in situ hybridization (FISH) and polymerase chain reaction restriction fragment length polymorphism (RFLP) analysis. X and Y chromosomes were detected using sex chromosome-specific probes in the FISH analysis, and HLA-DPBI antigens were examined in the RFLP analysis. Eyes receiving conventional penetrating keratoplasty (PKP) served as controls. RESULTS: Donor-derived epithelial cells were detected in three of five eyes (60.0%) in the FISH analysis and in seven of nine eyes (77.8%) in the RFLP analysis. Among these eyes, one and three eyes in the FISH and RFLP analysis, respectively, had both donor- and recipient-derived cells. In control PKP eyes, none of the eyes in the FISH analysis and one of eight eyes (12.5%) in the RFLP analysis had donor-derived cells. CONCLUSIONS: These results suggest that donor-derived cells survive much longer after LAT than those after PKP, and that LAT may function as stem cell transplantation of the corneal epithelium.  (+info)

Inhibition of vascular endothelial cell morphogenesis in cultures by limbal epithelial cells. (4/345)

PURPOSE: To study the in vitro angiogenic activity of human conjunctival and limbal epithelial cells and conjunctival, limbal, and corneal fibroblasts in a three-cell-type coculture model. METHODS: Human umbilical vein endothelial cells (EC) were cocultured with epithelial cells, fibroblasts, or epithelial cells and fibroblasts to test their effect on EC morphogenesis. Neutralizing antibodies to some known angiogenic factors were added to the culture to see whether the EC morphogenesis may be blocked by a particular antibody. RESULTS: Conjunctival and limbal epithelial cells exhibited very little or no stimulatory effect on EC tube formation when examined in an EC- epithelial cell coculture system. In contrast, conjunctival, limbal, and corneal fibroblasts all promoted EC morphogenesis when examined under the same culture conditions. Fibroblast-induced EC morphogenesis was inhibited by addition of anti-vascular endothelial growth factor (VEGF) and/or anti-basic fibroblast growth factor (bFGF) antibodies to the culture medium. In the three-cell-type coculture system consisting of ECs, fibroblasts, and epithelial cells, limbal epithelial cells (but not conjunctival epithelial cells) exhibited a strong inhibitory effect on fibroblast-induced EC tube formation. CONCLUSIONS: The proangiogenic activity of ocular surface fibroblasts is probably mediated through a paracrine mechanism by VEGF and bFGF. Limbal epithelial cells, but not conjunctival epithelial cells, inhibit fibroblast-stimulated angiogenesis.  (+info)

Allo-limbal transplantation in patients with limbal stem cell deficiency. (5/345)

AIM: To report the outcome of a series of patients with stem cell deficiency who underwent allo-limbal transplantation and to describe a technique for this procedure. METHODS: Six consecutive patients underwent allo-limbal stem cell transplantation. The primary diagnosis included alkali burn (n = 2), trachoma (n = 1), chronic rosacea blepharitis and kerato-conjunctivitis (n = 1), aniridia (n = 1), and Stevens-Johnson syndrome (n = 1). The limbal rim consisted of peripheral cornea and perilimbal sclera. FK-506 was used postoperatively for immunosuppression. RESULTS: The length of follow up ranged from 3 to 24 months (mean follow up 11.8 (SD 9.3) months). The outcome was considered satisfactory in five of six cases. The corneal surface was completely epithelialised within 2 weeks, and there was a substantial improvement in vision and symptoms. One patient had recurrent epithelial defects related to eyelid abnormalities. No side effects associated with systemic immunosuppression were noted. CONCLUSION: Allo-limbal transplantation, with systemic immunosuppression with FK-506 is useful in reconstruction of the ocular surface with improvement in vision in patients with severe stem cell deficiency.  (+info)

Expression of a single pair of desmosomal glycoproteins renders the corneal epithelium unique amongst stratified epithelia. (6/345)

PURPOSE: To determine desmosomal glycoprotein isoform expression in bovine corneal, limbal, and conjunctival epithelium and desmosomal profile and distribution during corneal re-epithelialization. METHODS: Immunofluorescence (IF) for desmosomal components on cryostat sections of fresh epithelia was supported by immunoblot analysis of tissue lysates. Wounded corneas maintained in organ culture were examined by IF at times up to full re-epithelialization (96 hours). RESULT: Immunofluorescence for desmoplakin confirmed desmosome presence throughout all three epithelia. Plakoglobin was also ubiquitous. Of the desmosomal glycoproteins, desmocollin 2 (Dsc2) and desmoglein 2 (Dsg2) were expressed throughout, but Dsc3 and Dsg3 were confined to the limbus and conjunctiva, and Dscl and Dsgl were absent. Dsc2 and Dsg2 IFs were stronger in superficial layers, but Dsc3 and Dsg3 were stronger basally, fading suprabasally. Glycoprotein expression in cornea and conjunctiva was confirmed by immunoblot analysis. No change in glycoprotein expression occurred during re-epithelialization. CONCLUSIONS: Uniquely among stratified epithelia, cornea expresses only a single pair of desmosomal glycoproteins, Dsc2 and Dsg2. Expression of Dsc3 and Dsg3 in limbus and conjunctiva coincides with their association with cell proliferation in other epithelia, but corneal epithelial cells did not express Dsc3 or Dsg3 during re-epithelialization. Absence of Dscl and Dsgl correlates with lack of keratinization in ocular epithelia. These expression patterns may have significance for the specific properties and differentiation patterns of the epithelia. Presence of desmosomes throughout re-epithelialization raises the question of how migrating cells mutually re-position.  (+info)

Detection of gonioscopically occludable angles and primary angle closure glaucoma by estimation of limbal chamber depth in Asians: modified grading scheme. (7/345)

AIM: To evaluate the performance of limbal chamber depth estimation as a means of detecting occludable drainage angles and primary angle closure, with or without glaucoma, in an east Asian population, and determine whether an augmented grading scheme would enhance test performance. METHOD: A two phase, cross sectional, community based study was conducted on rural and urban areas of Hovsgol and Omnogobi provinces, Mongolia. 1800 subjects aged 40 to 93 years were selected and 1717 (95%) of these were examined. Depth of the anterior chamber at the temporal limbus was graded as a percentage fraction of peripheral corneal thickness. An "occludable" angle was one in which the trabecular meshwork was seen in less than 90 degrees of the angle circumference by gonioscopy. Primary angle closure (PAC) was diagnosed in subjects with an occludable angle and either raised pressure or peripheral anterior synechiae. PAC with glaucoma (PACG) was diagnosed in cases with an occludable angle combined with glaucomatous optic neuropathy and consistent visual morbidity. RESULTS: Occludable angles were identified in 140 subjects, 28 of these had PACG. The 15% grade (equivalent to the traditional "grade 1") yielded sensitivity and specificity of 84% and 86% respectively for the detection of occludable angles. The 5% grade gave sensitivity of 91% and specificity of 93% for the detection of PACG. The interobserver agreement for this augmented grading scheme was good (weighted kappa 0.76). CONCLUSIONS: The traditional limbal chamber depth grading scheme offers good performance for detecting occludable drainage angles in this population. The augmented scheme gives enhanced performance in detection of established PACG. The augmented scheme has potential for good interobserver agreement.  (+info)

Autologous limbal transplantation in patients with unilateral corneal stem cell deficiency. (8/345)

AIM: To describe a surgical technique for autologous limbal stem cell transplantation and the outcome of a series of patients with unilateral stem cell deficiency. METHODS: A report of six consecutive patients who underwent autologous limbal stem cell transplantation is presented. The primary diagnosis included alkali burn (n=3), conjunctival intraepithelial neoplasia (CIN) (n=1), recurrent pterygium (n=1), and contact lens induced keratopathy (n=1). The autologous transplanted tissue consisted of peripheral cornea, limbus, and conjunctiva obtained from the contralateral eye. Three of the above patients underwent penetrating keratoplasty in association with auto-limbal transplantation. A significant modification to established techniques was the close monitoring of conjunctival epithelial migration in the immediate postoperative period. If conjunctival epithelium threatened to migrate on to the corneal surface, it was mechanically removed at the slit lamp and prevented from crossing the limbus. This was required in three patients. RESULTS: The mean follow up was 18.8 months. The outcome was satisfactory in all cases: a stable corneal surface was restored and there was a substantial improvement in vision and symptoms. One patient had a primary failure of the corneal allograft associated with glaucoma, and 6 months later developed a retinal detachment. No complications were noted in the donor eye with the exception of one patient who developed filamentary keratitis along the edge of the donor site. CONCLUSION: Autologous limbal transplantation with corneal, limbal, and conjunctival carriers was found to be useful for ocular surface reconstruction, over a mid-term follow up, in patients with unilateral stem cell deficiency. Close monitoring of the migration of conjunctival epithelium in the immediate postoperative period, and preventing it from crossing the limbus, ensured that the corneal surface was re-epithelialised exclusively from epithelial cells derived from the transplanted limbal tissue. This approach should improve the success of this procedure.  (+info)