CYTOLOGIC EVIDENCE OF CORNEAL DISEASES WITH LIMBAL STEM-CELL DEFICIENCY

Purpose: To determine which human corneal diseases show similar abnorm al corneal surfaces, characterized by conjunctival epithelial ingrowth (conjunctivalization), vascularization, and chronic keratitis (i.e,, a constellation of signs termed limbal stem cell dysfunction [deficien cy], which have been noted in experimental rabbit models). Methods: A total of 134 impression cytology specimens of the perilimbal region co llected from 1984 to 1994 were reviewed. Limbal deficiency was diagnos ed if conjunctival goblet cells were found on the corneal surface, Res ults: Ninety-four patients were found to have limbal deficiency. Categ ory 1 comprised 53 patients with a clear history showing limbal stem c ell destruction by chemical/thermal burns, Stevens-Johnson syndrome, m ultiple surgeries and cryotherapies, contact lens wear, and severe mic robial keratitis. Patients in category 2 (n = 41), did not have such a history, but gradual loss of stem cell functions over time was disclo sed and included diverse causes such as aniridia, multiple endocrine d eficiencies, neurotrophic keratopathy, peripheral inflammatory keratop athy or limbitis, and idiopathy. The 40 remaining patients with suspic ious findings did not have limbal deficiency, Conclusions: Impression cytology can be used to diagnose and monitor corneal diseases with lim bal deficiency, which manifest distinct clinical problems and are gene rally poor candidates for penetrating keratoplasty. The identification of category 1 diseases allows one to consider limbal (stem cell) tran splantation for surface reconstruction, The presence of category 2 dis eases indicates that limbal stem cell functions can be modulated by de velopmental, hormonal, neuronal, vascular, and inflammatory factors in the limbal stroma.