IMPAIRED CONTRAST SENSITIVITY IN ADOLESCENTS AND YOUNG TYPE-1 (INSULIN-DEPENDENT) DIABETIC-PATIENTS WITH MICROALBUMINURIA

We compared neurosensorial visual function by psychophysical tests (macular recovery time and contrast sensitivity) in two well matched groups of young Type 1 (insulin-dependent) diabetic patients with micro- and normoalbuminuria, respectively. The patients had normal visual acuity (greater than or equal to 1.0) and either no retinopathy or non-proliferative retinopathy. Thirty patients with microalbuminuria (albumin excretion greater than or equal to 15 mu g/min in a least two out of three timed overnight urine samples) were matched (age, diabetes duration, mean one-year HbA(1c), gender) with normoalbuminuric (n = 27) patients. Retinopathy (50 degrees colour fundus photography) was assessed by counting microaneurysms and hemorrhages as 'red spots'. Contrast sensitivity was examined for the spatial frequencies of 1.5, 3, 6, 12 and 18 cycles per degree (cpd). Macular recovery time (nyctometry) refers to the time-related (2 min) ability of the retina to regain visual acuity following exposure to bright light (photostress). Contrast sensitivity score was reduced in patients with microalbuminuria compared to those without; 18 cpd (mean and 95% confidence intervals): [4.2 (3.8-4.7) vs 5.0 (4.6-5.4), p = 0.03]. Macular recovery performance was not significantly reduced: [21.0 arbitrary units (17.5-24.6) vs 26.0 (22.6-30.7), p = 0.12]. We conclude that impaired contrast sensitivity independent of background retinopathy is shown in a group of young Type 1 (insulin-dependent) diabetic patients with low-grade microalbuminuria compared to a group of patients with normoalbuminuria.