Early Choroidal Microvascular Alterations Detected by Optical Coherence Tomography 3 Angiography in Diabetic Eyes Without Retinopathy

Purpose: To evaluate early choroidal microvascular alterations in diabetic eyes without clinically detectable retinopathy using optical coherence tomography angiography (OCTA), with quantitative analysis of choriocapillaris (CC) flow voids and en face Haller's layer metrics. Methods: This study included 102 eyes divided into three groups: healthy controls, diabetic patients without DR (no DR group), and those with non-proliferative DR (NPDR group). Spectral-domain OCT and swept-source OCT were used to assess choriocapillaris (CC) voids, Haller's layer vessels, and subfoveal choroidal thickness (SFCT) lag. Results: The average size and total area of CC voids significantly increased with DR severity, indicating early microvascular impairment. In contrast, there were no significant differences in the thickness or area of Haller's layer vessels among the groups. CC void changes were independent of SFCT. Conclusions: CC void parameters may serve as early imaging biomarkers of diabetic choroidopathy, even before the development of DR. These findings support the use of noninvasive OCTA as a tool for early detection and monitoring of choroidal changes in diabetic eyes.