Choroidal Flow Deficit Linked to Type 2 Diabetes Duration, Study Offers New Insights for DR Screening

The choriocapillaris, a dense network of capillaries located beneath the retina, is essential for supplying blood to the outer retinal layers, and its functional changes or blood flow impairments have been linked to the development of diabetic complications. Diabetes mellitus (DM) causes microvascular damage due to prolonged hyperglycemia, even before any visible retinal changes occur. With this in mind, Lourdes Vidal-Oliver, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, Mannheim, Germany, and colleagues aimed to investigate the relationship between optical coherence tomography angiography (OCTA) measurements and the duration of disease in type 2 diabetic patients without retinopathy, to better understand the early vascular changes associated with diabetes.

For this purpose, the researchers included 82 eyes from 82 type 2 diabetic patients without diabetic retinopathy (DR). They measured choriocapillaris flow deficit (CC FD%), vessel density (VD), and vessel length density (VLD) in both the superficial vascular plexus (SVP) and deep vascular plexus (DVP), comparing these parameters across different macular sectors. Additionally, the circularity of the foveal avascular zone (FAZc) was assessed.

To evaluate the relationship between each vascular parameter and disease duration, linear regression analysis was performed in univariate and multivariate models, with adjustments made for age, sex, HbA1c levels, and arterial hypertension.

The study led to the following findings:

• Choriocapillaris flow deficit (CC FD%) increased by 3.7%, 2.3%, 3.8%, and 4.6% in the nasal, superior, temporal, and inferior macular sectors, respectively, for each additional decade of disease duration, after adjusting for confounding factors.
• Mean vessel density (VD) and vessel length density (VLD) in both the superficial vascular plexus (SVP) and deep vascular plexus (DVP) decreased as the duration of diabetes increased, though the associations were weaker.
• Only VD in the superior and temporal sectors of the SVP showed a significant relationship in the multivariate analysis, with β = -0.12 for the superior sector and β = -0.13 for the temporal sector.
• The circularity of the foveal avascular zone (FAZc) also decreased with increased diabetes duration, but the observed association was weaker.

"Our findings demonstrate that the choroidal flow deficit percentage significantly rises with the duration of type 2 diabetes in patients without clinically visible retinopathy. This suggests that choroidal parameters could serve as potential markers for tracking disease progression and may be valuable tools in diabetic retinopathy screening and risk assessment," the researchers wrote.

"Longitudinal studies are necessary to further explore the role of choroidal changes in predicting the onset of diabetic retinopathy, which could help tailor individualized screening protocols," they concluded.

Reference:

Vidal-Oliver, L., Herzig-de Almeida, E., Spissinger, S. et al. Choriocapillaris flow deficit is associated with disease duration in type 2 diabetic patients without retinopathy: a cross-sectional study. Int J Retin Vitr 10, 91 (2024). https://doi.org/10.1186/s40942-024-00611-y