CORNEAL AUTOFLUORESCENCE IN DIABETIC AND NORMAL EYES

Corneal autofluorescence has been lately studied as a predictor of ret inopathy severity in diabetic patients. We measured corneal autofluore scence in 138 eyes of 69 diabetic patients and 64 eyes of 32 healthy c ontrols. Diabetic patients were subdivided by the severity of retinopa thy according to the Modified Airlie House Classification (stage 1: no or minimal retinopathy; stage 2: minimal background retinopathy; stag e 3: background retinopathy; stage 4: (pre-) proliferative retinopathy . The fluorescence peak value and the area underlying the corneal auto fluorescence curve were measured with a scanning fluorophotometer (Flu orotron Master, Coherent Radiation Pale Alto CA) Healthy controls' val ues of corneal autofluorescence (peak value: mean 11.03 +/- 3.77 ng. e quivalent fluorescein/ml; area: mean 163.85 +/- 61.40 scan-point x ng. equivalent fluorescein/ml) resulted similar (peak value: p = 0.83; ar ea: p = 0.61) to those of diabetic patients without retinopathy (peak value: mean 11.2 +/- 3.4 ng.eq/ml; area: 170.07 +/- 57.23 scan-pnt.ng. eq/ml). A statistically significant difference was found between diabe tic patients without retinopathy and patients with stage 2, 3, 4 retin opathy. No statistically significant difference was found both for the peak value (p = 0.50) and for the area (p = 0.61) between stage 3 and stage 4 retinopathy. The sensitivity and specificity of corneal autof luorescence as a screening test for diabetic retinopathy were 82% and 62% for the peak value, 87% and 60% for the area; the positive predict ive value for the presence of diabetic retinopathy was 65% for the pea k and 63% for the area.