Posterior polymorphous corneal dystrophy: a disease characterized by epithelial-like endothelial cells which influence management and prognosis.

This thesis contains a clinical and laboratory summary of findings in PPMD and, for the first time, reports the results of a large series of patients who underwent keratoplasty surgery. Posterior polymorphous dystrophy is bilateral and autosomal dominantly inherited. Slit lamp findings include corneal edema in the more advanced cases, calcific and lipid degenerative changes in severe cases, band-like lesions at the level of Descemet's membrane, localized or diffuse thickenings of Descemet's membrane, posterior corneal vesicular-like lesions, islands of abnormal cells surrounded by normal-appearing endothelial cells. Iridocorneal adhesions ranged in severity from fine or broad-based adhesions seen only on gonioscopy to large iridocorneal adhesions often associated with a glass-like membrane that are seen easily by slit lamp examination. All patients with broad-based iridocorneal adhesions have elevated intraocular pressure. Some patients have elevated pressure but no adhesions. Laboratory examination of corneal, iris, and trabecular meshwork tissue from patients undergoing penetrating keratoplasty and filtering operations reveals an abnormal endothelial cell layer covering the posterior cornea and growing across the trabecular meshwork and onto the iris. Although this tissue contains a variety of cells, the most prominent type is an epithelial-like cell. Extensive laboratory studies demonstrate features in common between the epithelial-like cells and normal epithelium. These include a multilaminar pattern, desmosomal junctions, microvillous projections, cytoplasmic keratin, sparse mitochondria, and rapid growth in tissue culture. These cells appear to determine the management and prognosis of patients with PPMD undergoing surgery. Twenty-two corneal transplants were performed on 20 eyes of 13 patients with PPMD. Their ages ranged from 11 to 77 years. The follow-up time after keratoplasty averaged 4.75 years. Nine grafts (41%) failed. Two failed because of an endothelial rejection, three because of glaucoma, one because of a retrocorneal membrane, two from both a retrocorneal membrane and glaucoma, and one from both an endothelial rejection and glaucoma. Thus, glaucoma was involved in six of the nine failures (27% of all grafts). Clinically visible retrocorneal membranes formed in 4 of the 22 grafts. All four eyes had preoperative slit lamp-visible iridocorneal adhesions. The factor that most prominently influences keratoplasty prognosis is the presence of iridocorneal adhesions.(ABSTRACT TRUNCATED AT 400 WORDS)