Early Detection of Diabetic Retinopathy Using Capillaroscopy: A Review

Diabetes is a disease that can cause eye damage without showing symptoms in its early stages. Diabetic retinopathy is one of the most severe complications of diabetes, affecting the small blood vessels in the eye's retina and potentially leading to blindness. The earlier the disease is detected, the higher the chances of a complete recovery. Capillaroscopy is a non-invasive medical instrument that allows for the full visualization of the capillary network underneath the skin. Using stereo-microscopic imaging, capillaroscopy is capable of measuring changes in blood vessel diameter, density, and structure. Research results show that early diabetic retinopathy exhibits significant changes in specific indicators of the vascular network, such as reduced capillary density and increased capillary divergence. The analysis is based on data from a grant-supported clinical trial involving 300 type 2 diabetes patients. Participants were divided into two groups: one group without retinopathy and another with early signs of microaneurysms. In the capillary imaging process, images of the subcutaneous layer were taken from small areas of the body surface. In addition to detailed demographic and treatment history data, regular measurements of blood glucose levels, hemoglobin A1c, and central corneal thickness were taken to detect retinopathy. Capillaroscopy measurements were analyzed using an automated software program. This technology measures mean vessel diameter (MVA), fine vessel characteristics (MVC), and medium-vessel geometric changes (MVD). The presented results indicate that as the severity of diabetic retinopathy increases, capillary density initially decreases and geometric variations in the intermediate vessels increase. These changes serve as indicators for measuring treatment efficacy in diabetic patients, especially in cases where the response to treatment intensity is often overlooked. The aggregated data shows that capillary imaging creates a potential future in medicine as a universal diagnostic tool, enabling doctors to diagnose disease even in the absence of early signs.