Corneal autofluorescence: an indicator of diabetic retinopathy

The metabolic disorder in diabetics often results in progressive retinopathy with severe visual impairment. Changes in metabolism can influence corneal autofluorescence. This has led to speculation that diabetic retinopathy might be associated with changes in corneal autofluorescence. Corneal autofluorescence of both eyes was determined by fluorophotometry in 94 insulin-dependent diabetes mellitus patients and in 46 healthy controls to evaluate its correlation with diabetic retinopathy. The modified Airlie House classification was used for grading diabetic retinopathy: (1) no or negligible retinopathy; (2) minimal background retinopathy; (3) background retinopathy; and (4) (pre-) proliferative retinopathy. The corneal autofluorescence values of grade 1 retinopathy patients did not differ significantly from those of the healthy controls (mean +/- standard deviation in ng equivalent fluorescein/ml: 11.6 +/- 3.0 and 11.4 +/- 2.8, respectively; P = 0.8). The means of grade 2, 3, and 4 retinopathy patients (mean +/- standard deviation in ngEq fluorescein/ml: 16.2 +/- 4.4, 16.7 +/- 4.3, 20.9 +/- 5.4, respectively) were significantly higher than the means of grade 1 patients and healthy controls (P less than 0.004). The mean values of patients with grade 4 were significantly higher than those of patients with grades 2 and 3 (P less than 0.01). The sensitivity and specificity of corneal autofluorescence as a screening test for diabetic retinopathy were 80% and 76%, respectively; the positive predictive value for the presence of retinopathy was 90%. The values for screening on (pre-) proliferative diabetic retinopathy were 68%, 72%, and 58%, respectively. These data show corneal autofluorescence to be an adequate indicator of diabetic retinopathy.(ABSTRACT TRUNCATED AT 250 WORDS)