Cytologlogic Evidence of Corneal Diseases with Limbal Stem Cell Deficiency

Abstract

PURPOSE: To determine which human corneal diseases show similar abnormal corneal surfaces, characterized by conjunctival epithelial ingrowth (conjunctivalization), vascularization, and chronic keratitis (i.e., a constellation of signs termed limbal stem cell dysfunction [deficiency], which have been noted in experimental rabbit models). METHODS: A total of 134 impression cytology specimens of the perilimbal region collected from 1984 to 1994 were reviewed. Limbal deficiency was diagnosed if conjunctival goblet cells were found on the corneal surface. RESULTS: Ninety-four patients were found to have limbal deficiency. Category 1 comprised 53 patients with a clear history showing limbal stem cell destruction by chemical/thermal burns, Stevens-Johnson syndrome, multiple surgeries and cryotherapies, contact lens wear, and severe microbial keratitis. Patients in category 2 (n = 41), did not have such a history, but gradual loss of stem cell functions over time was disclosed and included diverse causes such as aniridia, multiple endocrine deficiencies, neurotrophic keratopathy, peripheral inflammatory keratopathy or limbitis, and idiopathy. The 40 remaining patients with suspicious findings did not have limbal deficiency. CONCLUSIONS: Impression cytology can be used to diagnose and monitor corneal diseases with limbal deficiency, which manifest distinct clinical problems and are generally poor candidates for penetrating keratoplasty. The identification of category 1 diseases allows one to consider limbal (stem cell) transplantation for surface reconstruction. The presence of category 2 diseases indicates that limbal stem cell functions can be modulated by developmental, hormonal, neuronal, vascular, and inflammatory factors in the limbal stroma.