Correlation between renal function and OCTA parameters of the retina and choroid in early-stage diabetic patients

To explore the associations between renal function and retinal/choroidal microvascular characteristics as well as structure through swept-source optical coherence tomographic angiography (SS-OCTA). This cross-sectional study recruited diabetic patients without diabetic retinopathy (DR) who visited the National Metabolic Management Center (MMC) in Shanghai General Hospital, Shanghai, China. The 6 mm×6 mm fundus images obtained by SS-OCTA were divided into three rings: a central ring (C, 1 mm), an inner ring (I, 3 mm), and an outer ring (O, 6 mm). The perfusion and vessel length density of the superficial and deep capillary plexus (SCP-PD, SCP-VLD, DCP-PD, DCP-VLD), foveal avascular zone (FAZ), macular thickness (MT), choroid thickness (CT), choroid volume (CV) and choroidal vascularity index (CVI) were evaluated. Renal function was reflected by the urinary microalbumin‒creatinine ratio (UACR), estimated glomerular filtration rate (eGFR), blood urea nitrogen (BUN) and the renin‒angiotensin‒aldosterone system (RAAS). Pearson correlation coefficients, multivariate analyses and interaction analyses were used to analyse the correlations between OCTA parameters and renal function. eGFR was positively correlated with the SCP-PD (Average, C, I, O), SCP-VLD (Average, C, I), DCP-PD (C, I), DCP-VLD (C, I), CT (C, I, O, Overall) and CV (C, I, O, Overall). BUN was negatively correlated with the SCP-PD (C), SCP-VLD (C), DCP-PD (C, I), DCP-VLD (C), FAZ circulation. UACR was negatively correlated with the SCP-PD (C) and SCP-VLD (C). Angiotensin was negatively correlated with the SCP-PD (C), MT (C, I). According to the multivariate analysis, as chronic kidney impairment progressed, the SCP-PD (C) and SCP-VLD (C) decreased. There are significant correlations between renal function and retinal/choroidal structural and microvascular characteristics in diabetic patients without DR. These findings suggest that OCTA-derived parameters may serve as potential early biomarkers for diabetic microvascular complications.