Corneal sensitivity, as measured with an aesthesiometer, was determined in a group of diabetics and in an age and sex-matched population of nondiabetics. There was a statistically significant difference (P<.003) between the two groups, with diabetic patients having a much higher incidence of elevated tactile corneal thresholds. In each diabetic subject, the two corneas tended to be symmetrically involved. Presumably, this sensory deficit is the consequence of a diffuse polyneuropathy that includes both trigeminal nerves or their branches.
The decrease in corneal sensitivity may be observed shortly after the onset of diabetes in some patients, and it appears that tactile corneal thresholds do rise with increased duration of diabetes. Age does not appear to influence corneal sensitivity.
The degree of corneal anesthesia found in diabetics does not lead to serious consequences in an otherwise healthy eye.
Schwartz DE. Corneal Sensitivity in Diabetics. Arch Ophthalmol. 1974;91(3):174-178. doi:10.1001/archopht.1974.03900060182003