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

Background, Although diabetic retinopathy has been thoroughly studied, litt le attention has been given to the corneal changes of diabetic patients. Pa thophysiologic 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 e lectron microscopic ultrathin sections were prepared from corneas of 16 non insulin-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 contr ols. Results. In addition to the epithelial changes that include accumulati on of glycogen granules, occasional focal epithelial cell degeneration, and irregular thickening and multilamination of the epithelial basement membra ne, unusual 120-nm wide-spaced collagen fibril bundles were observed scatte red among both Descemet's membrane and stromal matrix. Conclusions. The agg regates of wide-spaced collagen fibrils, which have not been described in o ther basement membranes of diabetic patients, may reflect an excessive glyc osylation rate.