Abstract
Superior limbic keratoconjunctivitis (SLK) is a condition of unknown etiology. Histological signs include acanthosis, dyskeratosis, keratinization, and ballon degeneration of the bulbar conjunctival epithelium. Ultrastructural examination of biopsy material from five eyes of patients with SLK shows numerous nuclear changes in the conjunctival epithelial cells. These include abnormal distribution and aggregation of nuclear chromatin, the presence of filaments within the nucleus, and dense accumulations of cytoplasmic filaments which surround the nucleus, resulting in "strangulation" and the formation of multilobed nuclei or multinucleated cells. These changes do not appear to have been described previously in any cell type.