RELATIONSHIP BETWEEN CONTRAST SENSITIVITY AND METABOLIC CONTROL IN DIABETICS WITH AND WITHOUT RETINOPATHY

Contrast sensitivity was studied in diabetic adolescents and young adu lts with and without retinopathy in order to evaluate their central vi sion, to analyze the relationship of metabolic control to the presence and severity of retinopathy, and to re-evaluate the response to this test after a significant improvement in metabolic control. Twenty adol escent and young adult diabetics without retinopathy and 40 diabetics with retinopathy of varying degree were enrolled in the study; 20 heal thy age and sex-matched subjects served as controls. Contrast sensitiv ity was assessed with a CSV-1000 contrast testing instrument, testing for four spatial frequencies, 3, 6, 12 and 18 cycles per degree (cpd). Diabetics with no retinopathy showed a weak but significant differenc e at 18 cpd compared with controls (P = 0.04), while diabetics with ba ckground retinopathy showed a significant reduction of contrast sensit ivity at 12 and 18 cpd when compared with controls (P<0.001). In patie nts with preproliferative/proliferative retinopathy a highly significa nt reduction of contrast sensitivity at all frequencies was found comp ared with controls. Furthermore, these patients had a significantly lo wer mean contrast sensitivity than patients without retinopathy. The p atients were reevaluated after a significant amelioration of metabolic control. An improvement in contrast sensitivity was found in diabetic s without retinopathy and with background retinopathy, while there was no change observed in diabetics with severe retinopathy. These result s show that diabetic adolescents and young adults with and without sig ns of retinopathy observed by fluorescein angiography have a reduced c ontrast sensitivity, which is more severe in patients with preprolifer ative/proliferative retinopathy. A significant amelioration of metabol ic control is associated with an improvement of contrast sensitivity i n all patients with the exception of those patients who had signs of p reproliferative/proliferative retinopathy observed by fluorescein angi ography. In summary, this longitudinal study provides the first eviden ce that reduced contrast sensitivity is reversible in diabetics with o r without background retinopathy only.