Evaluating retinal circulation using video fluorescein angiography in control and diabetic rats

Video fluorescein angiography has been used to evaluate retinal circulatory parameters in diabetic and non-diabetic Sprague-Dawley rats. Video fluorescein angiograms were recorded from the retina using a modified retinal fundus camera following a 5 ul bolus injection of sodium fluorescein dye into the jugular vein. Retinal circulatory parameters were measured using computer assisted image analysis. These analyses were performed on 25 diabetic rats with 1 week duration of diabetes and 26 matched, non-diabetic, rats. There was a significant (p = .0001) increase in retinal Mean Circulation Time (MCT) in the diabetic group (1.83 +/- 0.40 s) compared to the control group (1.09 +/- 0.27 s). There were no significant differences in arterial or venous diameters comparing diabetic and control groups. In a separate paired experiment, measurements were made from the same animals both before and after one week duration of diabetes. A paired t-test analysis demonstrated significantly increased MCT times in the 6 diabetic animals (p = .001) while there was no significant differences detected in the 4 corresponding control animals. These results indicate that significant increases in retinal circulation times can be measured as early as 1 week after streptozotocin induced diabetes in this animal model.