Comparing wall to lumen ratio (WLR) in involved and less involved areas within diabetic individual

Background: Small arterioles undergo structural changes and remodeling in diabetic retinopathy. This study aims to analyze arterial retinal structure in diabetic patients with no other retinal disease to test whether diabetes is associated with higher arteriolar wall-to-lumen ratio (WLR) compared to control subjects. In addition, to test whether arteriolar WLR is influenced by local diabetic retinal abnormalities within a single individual's eye.;Methods: The study compared 26 diabetic subjects: 11 females (42%) and 15 males (58%), age range (32 to 76) years old, mean (53.55 +/- 11.80) to 25 control subjects: 14 females (56%) and 11 males (44%), age range (23 to 58) years old, mean (33.47 +/-14.18). The measurements were made using the Indiana AOSLO both confocal and multiply scattered light imaging in a series of arterioles. For each arteriole selected, the outer diameter (OD) and inner diameter (ID) were measured five times and the results were used to calculate the (WLR). Measured arterioles were divided into two groups according to (ID) size. Group one was arterioles ≤ 30mum and group two was arterioles > 30mum but ≤ 75microm. Arterioles in diabetic subjects were also classified according to whether they were in more or less involved areas of the retina. An involved area was defined as being within 500mum of a retinal region that showed one or more of retinal diabetic changes; microaneurysms, hard exudates, cotton wool spots, cystoid edema, wall irregularity or intraretinal microvascular abnormalities (e.g. capillary looping and twisting). Less involved retinal areas lacked any of these features. A One-way ANOVA and T-test ware used for statistical analysis.;Results: WLR varied with arteriolar outer diameter. Small arterioles ≤ 30mum had greater WLR than large arterioles > 30mum in both diabetic (1.187 +/- 0.461 vs 0.681 +/- 0.370, P< 0.0001) and control subjects (0.967 +/- 0.559 vs 0.315 +/- 0.161, P small arterioles in control > large arterioles in diabetic >large arterioles in control. (1.1502 > 0.7821 > 0.6695 > 0.3029, P < 0.0001).;There was a relation between WLR and the presence of diabetic retinal changes (1.1834 +/- 0.553 vs 0.8897 +/- 0.402, P < 0.0001) in involved and less involved areas respectively. Sixteen subjects had arterioles measured in both involved and less involved areas and 11 of them had larger WLR in involved areas.;Conclusions: Vascular walls in diabetic patients can be directly and noninvasively measured by AOSLO. WLR is larger in diabetic subjects and the degree of change varies locally with diabetic retinal signs of diabetic involvement. This suggests that arteriolar wall to lumen ratio WLR could be a biomarker of microvascular complication in diabetic retinopathy.