Purpose To evaluate associations between optical coherence tomography angiography (OCT-A) metrics and diabetic retinopathy (DR) and compare their discrimination against conventional clinical risk factors.

Methods In this cross-sectional study, 108 adult eyes (right eye if both eligible) with diabetes were recruited from tertiary ophthalmology/optometry clinics. DR was clinically graded using ETDRS categories and dichotomised as no DR vs ≥ mild NPDR (primary outcome). Macular 6×6 mm OCT-A (Zeiss AngioPlex) was acquired; scans with signal strength >7 and without major artefact were included. Quantitative metrics from the superficial capillary plexus included vessel density (VD) and perfusion density (PD) (central/inner/outer/full regions); structural OCT measures and FAZ parameters were secondary. Associations with ≥ mild NPDR were assessed using multivariable logistic regression adjusted for age, sex, HbA1c, and diabetes duration. Discrimination was evaluated with ROC curves/AUC (95% CI) and DeLong comparisons of AUCs.

Results DR was present in 63% of eyes. DR was associated with lower VD (central, inner, outer, full) and lower PD (central, inner, full) (all p≤0.04). After adjustment, central VD (OR 0.82, 95% CI 0.68–0.98) and central PD (OR 0.92, 95% CI 0.86–0.99) remained independently associated with DR. The OCT-A model outperformed the clinical model (AUC 0.73 vs 0.60); the combined model yielded AUC 0.76.

Conclusion VD and PD from the superficial plexus are independently associated with DR and show superior discrimination versus conventional clinical factors alone, supporting OCT-A as an adjunct for earlier DR detection.

The authors have declared no competing interest.

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

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Ethical approval was obtained from the Southern Adelaide Local Health Network Human Research Ethics Committee (#HRE00228). All participants received written and verbal information about the study and provided written consent. The study adhered with the National Statement on Ethical Conduct in Human Research and the Declaration of Helsinki.

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