Combined granular-lattice ('Avellino') corneal dystrophy.

BACKGROUND/PURPOSE: In 1988, a report was published describing the histopathologic examination of corneal buttons of 4 patients who had undergone unilateral keratoplasty because of decreased vision caused by what had been diagnosed clinically as granular dystrophy. But on pathologic examination, lesions characteristic of both granular dystrophy and lattice dystrophy were found in each of the 4 corneal buttons. The patients came from 3 different families, each of which traced its origin to the Italian province of Avellino. We studied the clinical and histopathological features of 4 corneas affected by combined granular-lattice dystrophy, adding thereby to the total of 12 other corneas that have been so-described in the literature. METHODS: Two women underwent bilateral penetrating keratoplasty for what was diagnosed clinically as Reis-Bücklers dystrophy in the first patient, and as granular dystrophy in the second patient. We studied all 4 corneas pathologically, using both conventional hematoxylin and eosin stains as well as special histochemical techniques. RESULTS: All 4 corneas contained lesions characteristic of both granular dystrophy and lattice dystrophy, a circumstance that has given rise to the name "combined granular-lattice dystrophy." The patients are not known to be of Italian ancestry. CONCLUSIONS: Three clinical signs characterize combined granular-lattice dystrophy: (1) anterior stromal discrete, grayish-white deposits; (2) lattice lesions located in mid-stroma to posterior stroma; and (3) anterior stromal haze. Both clinically and histopathologically, the lattice lesions are of greater diameter than are those that occur in lattice dystrophy type I. In the past few years, striking advances have been made in understanding the genetics of combined granular-lattice dystrophy. The most recent of these was published just 2 months before the 1997 meeting of the American Ophthalmological Society, and establishes a common molecular origin for granular dystrophy, lattice dystrophy type I, Avellino dystrophy, and Reis-Bücklers dystrophy.