Ultrastructural changes in corneas of diabetic patients: An electron- microscopy study

Background. Although diabetic retinopathy has been thoroughly studied, little attention has been given to the corneal changes of diabetic patients. Pathophysiologic and clinical findings may be related to the ultrastructural changes found in these corneas. Purpose. To investigate the ultrastructural corneal changes of diabetic patients. Patients and Methods. Transmission electron microscopic ultrathin sections were prepared from corneas of 16 noninsulin-dependent diabetic patients (mean age, 65 years; range, 40-82 years) who suffered from the disease for a mean period of 22 years (range, 10-30 years). We used 16 corneas from healthy age-matched donors as normal controls. ResuLts. In addition to the epithelial changes that include accumulation of glycogen granules, occasional focal epithelial cell degeneration, and irregular thickening and multilamination of the epithelial basement membrane, unusual 120-nm wide-spaced collagen fibril bundles were observed scattered among both Descemet's membrane and stromal matrix. Conclusions. The aggregates of wide-spaced collagen fibrils, which have not been described in other basement membranes of diabetic patients, may reflect an excessive glycosylation rate.