Purpose
Advances in retinal imaging have allowed a better understanding of retinal vascular parameters and their relationship with underlying pathophysiologic processes in and beyond the retina. This study was conducted to compare the retinal arterial bifurcation angle in severe non-proliferative diabetic retinopathy and normal subjects.
Methods
This cross sectional study included 100 cases with severe non-proliferative diabetic retinopathy (NPDR) and 93 normal controls. The first and second retinal arterial bifurcation angles were quantified for both eyes of each subject by means of Adobe Photoshop CS5 software manually, adhering to a predefined protocol. The reliability of measurements was checked by determining the Intraclass Correlation Coefficient (ICC) of 2 separate angle measurements done by the same examiner.
Results
The measurements were reliable (ICC considered). The mean of first (86.91±14.57 Vs 74.21±12.24 and p<0.001) and second (88.61±17.13 Vs 71±12.92 and p<0.001) retinal arterial bifurcation angles in patients with severe non-proliferative diabetic retinopathy were significantly higher than normal subjects. The differences remained significant after adjusting for age, sex, glomerular filtration rate (GFR), duration of diabetes and hyperlipidemia. Also, the mean of first retinal arterial bifurcation angles in normal group was closer to the theoretical optimal bifurcation angle (of 75 degrees) compared to the diabetic group, in which this parameter showed significant difference to the optimum. (p<0.001)
Conclusions
Bifurcation angle of retinal arteries increases in severe NPDR and is a potential criterion for automated diagnosis of diabetic retinopathy.
Keywords: 499 diabetic retinopathy