Compensatory epithelial hyperplasia in human corneal disease.

Compensatory hyperplasia of the corneal epithelium (CEH) has been observed histopathologically in animal and human eyes after excimer laser photoablative keratectomy, and has been implicated as a cause of variable refractive results and refractive regression after this procedure. Retrospective histopathologic analysis of routine keratoplasty specimens revealed CEH in 85 of 130 (65%) corneas with keratoconus, 18 of 36 (50%) corneas with chronic herpes simplex virus (HSV) keratitis, and 14 of 25 (56%) corneas coded as nonspecific scars. Mild CEH occurred apically and/or peripherally in keratoconus. Massive CEH (up to 200 microns thick) occurred in chronic HSV keratitis with irregular stromal loss. Our data indicate that CEH occurs frequently in several corneal diseases marked by stromal ectasia or loss. We postulate that stromal loss may contribute to CEH by providing relative protection against exfoliative shearing forces of superior eyelid closure. Our study complements previous reports that imply that CEH is a contributory factor in refractive regression after excimer laser photoablation.