Flicker-induced retinal vessels dilatation in diabetic patients without clinically detectable diabetic retinopathy

Aim
Clinically detectable signs of diabetic retinopathy are preceded by endothelial dysfunction. Retinal microvasculature dynamics assessment using a dynamic vessel analyzer (DVA) may enable detection of neurovascular changes in vivo at the preclinical stage of diabetic complications and thus may help to recognize patients at increased risk of diabetic retinopathy. The aim of the study was to investigate the response of retinal vessels to flickering light in diabetic patients without clinically detectable diabetic retinopathy.

Materials and methods
Eighty eyes of 40 patients with type II diabetes and no clinically detectable diabetic retinopathy were enrolled in the study group. The control group consisted of 44 volunteers (88 eyes) without diabetes. The Dynamic Vessel Analyzer (DVA) was used to measure retinal vascular dilatation in response to flicker light stimulation.

Results
The AVR obtained by static vessel analysis was similar in both groups, whereas retinal vascular dilation after flicker stimulation in arterioles and veins was significantly reduced in the DM group (mean of 1.79% and 3.24%, respectively) compared with the control group (mean of 2.86% and 4.07%, respectively). DM was an independent factor associated with lower values of the flicker-light-induced vasodilation. A slight positive correlation was noted between the time of physical activity and better arterial response to flicker light in the diabetic group (Rs = +0.34, p = 0.03).

Conclusions
1. Retinal vessel reactivity to flicker light stimulation is reduced in diabetic patients with no clinically detectable signs of diabetic retinopathy. 2.DVA may be a valuable tool for early identification of patients at increased risk of diabetic retinopathy.