Choroidal Microvascular Alterations on Ultra-Widefield Swept-Source OCTA in Type 2 Diabetes: Associations with Outer Retinal Structural Changes and Systemic Risk Markers.

PURPOSE: To characterize choroidal microvascular alterations in diabetes without diabetic retinopathy (NDR) or mild non-proliferative diabetic retinopathy (NPDR) and evaluate associations with retinal structural changes and systemic risk markers.

METHODS

This retrospective cross-sectional study included 209 healthy controls, 203 patients with NDR, and 199 treatment-naïve patients with mild NPDR. Ultra-widefield swept-source optical coherence tomography angiography (UWF-SS-OCTA) quantified choroidal and retinal parameters. Systemic markers, including blood pressure, HbA1c, lipid profiles, and renal markers, were assessed in diabetic participants. Correlation analyses assessed associations of choroidal microvascular parameters with retinal structural changes in the overall population and diabetic participants. Multivariable regression evaluated associations with systemic risk markers, with NDR-specific sensitivity analyses.

RESULTS

Choriocapillaris vascular density (CC-VD) and choroidal vascularity index (CVI) were reduced in NDR versus controls, whereas retinal vascular density decreased only in NPDR (all p < 0.05). Outer retinal thickness and volume increased in NDR. In the overall cohort, both were inversely correlated with CC-VD and CVI (r = -0.25 to -0.30, all p < 0.001), with associations remaining significant in diabetic participants. Systolic blood pressure ≥140 mmHg and urinary albumin excretion rate >20 μg/min were independently associated with lower CC-VD (β = -1.03 and -1.36, respectively), whereas cystatin C >1.09 mg/L was associated with lower CVI (β = -0.92; all p < 0.05). These systemic associations persisted in NDR-specific analyses.

CONCLUSION

UWF-SS-OCTA revealed reduced CC-VD and CVI in diabetes without clinically apparent DR. Associations with outer retinal thickening and systemic risk markers suggest links among choroidal microvascular alterations, retinal structural changes, and systemic risk.