Correlation of corneal sensation, but not of basal or reflex tear secretion, with the stage of diabetic retinopathy

Purpose. To examine the possible relation between corneal sensation or tear secretion and the stage of diabetic retinopathy in diabetic patients. Methods. Total reflex or basal tear secretion and corneal sensation were determined in 95 patients with type 11 diabetes mellitus and 58 nondiabetic control subjects. Tear secretion was measured by the Schirmer test and corneal sensation with a Cochet-Bonnet esthesiometer. Results. Corneal sensation and total or reflex tear secretion were significantly reduced in diabetic patients compared with nondiabetic controls. The loss of corneal sensation, but not that of tear secretion, was significantly correlated with stage of diabetic retinopathy in diabetic patients who were diagnosed with no diabetic retinopathy, simple diabetic retinopathy, preproliferative retinopathy, or proliferative retinopathy. Conclusion. Both corneal sensation and total or reflex tear secretion are reduced in individuals with diabetes. The decrease in corneal sensation, but not that in each tear secretion, was correlated with the stage of diabetic retinopathy. Given that loss of corneal sensation is a manifestation of diabetic polyneuropathy, these results are consistent with the notion that both diabetic retinopathy and polyneuropathy result from a basement membrane abnormality.