Diabetic retinopathy is characterised by the local expansion of capillaries in the eye (microaneurysms). This results in a change in the flow and hemodynamic forces, meaning leakage, dysfunction, fluid accumulation (edema) and eventually blindness.
In this HOT article, a team led by Yaakov Nahmias at The Hebrew University of Jerusalem, Israel in combination with researchers at Stanford University and University of Florida, USA define a critical ratio of microaneurysm to vessel diameter for identification of high risk microaneurysms in diabetic retinopathy patients. This ratio determines the changes in flow speed, shear force and pressure.
The researchers used an analytical model to characterise this complex state. They calculated the critical ratio based on a shear threshold value for endothelial cell dysfunction. Above this critical ratio, leakage of the vessel is highly likely. This means that high risk vessels could be targeted for laser-ablation treatment, limiting the amount of unnecessary damage and making treatment more effective.
The validation was carried out using confocal images of diabetic retinas. This comparison also revealed that those microaneurysms over this critical threshold also display an increase in Von Villebrand Factor (vWF) expression. This is a biomarker for endothelial dysfunction and could help to explain the non-linear relationship between microaneurysm size and leakage.
This HOT article contains work relevant to the millions of people in developed countries diagnosed with diabetes and provides further understanding of the mechanisms of retinopathy. It’s free to access for the next 4 weeks*, just click on the link below:
Non-dimensional analysis of retinal microaneurysms: critical threshold for treatment
Elishai Ezra, Eliezer Keinan, Yossi Mandel, Michael E. Boulton and Yaakov Nahmias
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