The Effects of Allogeneic SLET

Simple limbal epithelial transplantation (SLET) was introduced in 2012 by Sangwan and coworkers to overcome the issues mainly related to the cost of a GMP-certified product and ease of surgical manipulations that al- lows use of smaller pieces of limbus from the contralateral eye (thus avoiding iatrogenic problems). A completely epithelialized, avascular and stable corneal surface was achieved by 6 weeks and was maintained in all recipient eyes at a mean follow-up of 9.2 ± 1.9 months. Best corrected visual acuity improved from worse than 20/200 in all recipient eyes before surgery to 20/40 or better in four (66.6%) eyes. None of the donor eyes developed any complications.Basu et al. reported autologous SLET on a population of 125 patients which included 65 adults and 60 children suffering from unilateral LSCD. 76% (95/125) of eyes maintained a successful outcome at final follow-up without progressive conjunctivalization, development of persistent epithelial defect, infection, or need for repeat SLET. Survival probability of 80% in adults and 72% in children after 1 year. So far, most of the reports have been about autoSLET, that is, the limbal explants are obtained from the unaffected eye of the same recipient, avoiding immune reaction at the later stage. Also, they demonstrated SLET had promising result both in adults and children. A study by Iyer and coworkers used alloSLET in early stages after ocular chemical injury to achieve rapid epithelialization. Instead of taking the biopsy from the recipient's healthy eye, they took it from a cadaveric donor and performed the SLET. Epithelialization and improved best corrected visual acuity and corneal phenotype were achieved at early stages; however, 7 of 18 eyes had a gradual failure of the allograft, and 5 eyes underwent subsequent limbal autograft. Symblepheron formation involving one to two quadrants was recorded in 3 eyes (16.7%). Visual rehabilitative procedures in the chronic phase of chemical injury, in most instances after alloSLET in the acute stage, did not require any keratoplasties. Unfortunately, most diseases causing limbal deficiency, e.g., surface burns (alkali/ thermal), Stevens-Johnson syndrome, contact lens-related epitheliopathy, and ocular cicatricial pemphigoid, tend to affect both eyes of a patient. Autologous SLET may not be applicable in patients with bilateral eyes involvement. In this study, the effect of allogeneic SLET will be investigated.