Retinal OCTA parameters and the risk of worsening kidney function in patients with type 2 diabetes: a longitudinal cohort study.

AIMS: To determine whether retinal optical coherence tomography angiography (OCTA) parameters are associated with subsequent worsening kidney function (WKF) in patients with type 2 diabetes (T2D) and to assess their relationship with early renal function trajectory.

METHODS

In this prospective cohort study, 180 patients with T2D underwent macular OCTA imaging and were followed for renal outcomes (median follow-up, 37 months). Cross-sectional associations between OCTA parameters and systemic biomarkers were examined. Multivariable Cox models adjusted for age, sex, diabetes duration, HbA1c, HDL-c, and baseline estimated glomerular filtration rate (eGFR) evaluated associations with WKF. eGFR slope over the first 12 months was estimated using linear mixed-effects models in 141 participants. Sensitivity analyses further evaluated image quality distributions, ocular comorbidities, single-eye selection, and additional adjustments for baseline renal/hemodynamic parameters. Exploratory mediation analysis assessed whether early eGFR slope accounted for OCTA-outcome associations.

RESULTS

Forty-two participants (23%) developed WKF. Several OCTA parameters correlated with systemic and renal biomarkers in unadjusted analyses but were not significant after multivariable adjustment. In primary adjusted Cox models, nasal inner-ring superficial vessel density (NI-SVD) was independently associated with WKF (HR, 1.10 per 1% increase; 95% CI, 1.02-1.19; p=0.013). Early eGFR slope (-1.53 ± 1.38 mL/min/1.73 m2/year) was strongly associated with WKF (HR, 0.70; 95% CI, 0.54-0.89; p=0.004). NI-SVD remained significant after adjustment for early eGFR slope (HR, 1.11; 95% CI, 1.02-1.21; p=0.021). Sensitivity analyses indicated that the association between NI-SVD and WKF remained consistent with the primary analysis. Mediation analysis did not demonstrate a statistically significant indirect effect (indirect HR = 1.02, 95% CI: 0.996-1.050).

CONCLUSIONS

NI-SVD, a parafoveal OCTA metric was independently associated with WKF in T2D. This association was not explained by early renal functional decline, suggesting that retinal microvascular alterations are independently linked to long-term renal prognosis in T2D.