Corneal autofluorescence was investigated by fluorophotometry in patients with non-insulin-dependent diabetes mellitus and healthy volunteers, and evaluated as to its correlation with diabetic retinopathy. The corneal autofluorescence of diabetes patients, which was significantly higher than that of healthy controls, correlated significantly with the severity of retinopathy. In addition, the corneal autofluorescence of burned-out retinopathy patients was significantly lower than that of proliferative retinopathy patients. These results suggest that corneal autofluorescence is correlated with retinal ischemia and that corneal autofluorescence can be an indicator of the activity of diabetic retinopathy. Corneal autofluorescence may originate in the accumulation of some factor induced by retinal ischemia within the corneal stroma.