Graded corneal sensitivity for screening of diabetic retinopathy

Several alternative approaches to screen diabetics followed by referral of patients with retinopathy changes, are being investigated. The intent is to demonstrate usefulness of a cost effective, easy and valid screening test. We investigated in this report the efficacy of graded corneal sensitivity for screening presence of diabetic retinopathy. In 105 randomly chosen subjects with (70 subjects) and without (35 subjects) diabetes mellitus, corneal aesthesiometry and status of retinopathy was determined independently. Corneal sensitivity in subjects of diabetes mellitus without retinopathy (1.17 +/- 0.29 gm/mm2) was significantly different when compared to healthy controls (0.99 +/- 0.04 gm/mm2) (p < 0.01). Also corneal sensitivity in eyes with any type of retinopathy was significantly worse (1.94 +/- 1.33 gm/mm2) when compared to eyes without retinopathy. At a cut off value of 1.20 gm/mm2 the sensitivity and specificity of corneal hypoesthesia as a test to detect diabetic retinopathy was 86% and 74%, respectively. For detecting presence of proliferative diabetic retinopathy at a cut off value of 1.49 gm/mm2 the sensitivity and specificity were 89% and 80% respectively. These observations indicate that corneal hypoesthesia may be a reasonable indication of the presence of diabetic retinopathy and could be used to screen diabetic populations for retinopathy, after its validity is confirmed in larger studies.