Clinical Significance of Conjunctival Microvascular Density in Diabetic Retinopathy: A Multimodal Correlation Study...

Diabetic retinopathy (DR) with media opacity presents a diagnostic challenge for retinal evaluation. This study investigated whether conjunctival microvascular assessment using swept-source optical coherence tomography angiography (SS-OCTA) can serve as a potential indicator of retinal pathology. We conducted a comparative study of 163 patients with diabetes (110 with DR, subdivided into 55 nonproliferative and 55 proliferative cases) and 49 age-matched healthy controls. All participants underwent SS-OCTA for conjunctival vessel density (VD) measurement and standard retinal OCTA for retinal VD and ganglion cell complex (GCC) analysis. Statistical correlations were performed to evaluate the relationship between the conjunctival and retinal parameters. Conjunctival VD showed a progressive reduction in DR severity, most prominently in the temporal region (70.7% in controls vs. 55.6% in patients with proliferative diabetic retinopathy [PDR]). Temporal conjunctival VD correlated well with retinal damage, and lower conjunctival density was linked to reduced retinal blood flow (r = 0.21-0.26) and thinner nerve layers (r = 0.22). No significant differences in VD were found between controls and patients with diabetes without DR, suggesting a specificity for retinopathic changes. SS-OCTA assessment of conjunctival VD may provide clinically useful information regarding the retinal status in patients with DR with compromised fundus visualization. This approach is a practical alternative when traditional retinal imaging is obstructed by media opacities.