Of 281 eyes that had had Sato's anterior-posterior radial keratotomy for myopia or myopic astigmatism, 80 (50 patients) underwent follow-up examinations ten to 20 years later. Sixty of the 80 eyes had bullous keratopathy. The onset of this disease occurred when the patient was about 40 years old, regardless of the patient's age at the time of surgery. Seven corneal buttons were obtained from patients with bullous keratopathy who required penetrating keratoplasty. Light and electron microscopy disclosed subepithelial bullae, degenerate or absent Bowman's zone, and thickened Descemet's membrane. Flattened fibroblastic endothelial cells were observed in three of the seven cases. This type of radial keratotomy surgery seems to produce severe corneal decompensation many years later, possibly as a result of damage from the corneal incisions in combination with endothelial losses from aging.