Abstract
Abstract: :
Purpose: To determine the effect of year-long treatment with the oral ACE Inhibitor lisinopril (10 mg per day) vs placebo on retinal blood flow and blood-retinal barrier permeability in a group of type I diabetic patients. Methods: We used a randomized, double-masked, placebo-controlled, parallel study design. Sixteen type I diabetic patients were recruited. Four were lost during follow-up. In the 12 patients that completed the study, average age was 30 years (range 19 to 44 years), average duration of diabetes was 10 years (range 3 to 17 years), and average age at onset was 20 years (range 8 to 36 years). Average length of follow-up was 11.4 months. Laboratory evaluations (HbA1c, serum potassium and creatinine, urinary microalbumin, and creatinine clearance) were performed at 3-month intervals. Ophthalmic evaluations, including retinal photography (ETDRS seven standard fields), retinal blood flow in a major temporal artery (Canon CLBF 100 laser Doppler instrument), and vitreous fluorophotometry (Ocumetrics Fluorotron Master), were performed at 6-month intervals. Nine patients had no observable retinopathy; 3 patients had retinal microaneurysms. Results: In the placebo group (n=8), retinal blood flow decreased by 15.6% ± 20.8% (mean ± sd) during follow-up. In the lisinopril group (n=4), retinal blood flow increased by 14.6% ± 10.9%. The difference between the groups was statistically significant (p = 0.027, Mann-Whitney U-test). There were no significant effects of changes in blood pressure or heart rate on the changes in blood flow. Changes in blood-retinal barrier permeability as calculated using the method of Van Best and Vreeswijk were directly correlated with the changes in retinal blood flow (r = 0.67, p = 0.016, n=12). Finally, in the placebo group, the changes in retinal blood flow during follow-up were directly correlated with the patient age at onset of diabetes (r = 0.82, p = 0.012, n=8). Conclusions: The results confirm earlier published reports of progressive decreases in retinal blood flow in type I diabetic patients with no or minimal retinopathy. Treatment with lisinopril appears to reverse this process. The relation between blood flow and calculated blood-retinal barrier permeability changes suggests that permeability measurements alone, without regard to blood flow, must be interpreted with caution.
Keywords: blood supply • diabetes • clinical (human) or epidemiologic studies: tre