Association between visceral adiposity indices and retinal microvascular parameters stratified by urinary protein status

Visceral fat accumulation is a well-established risk factor for both cardiovascular and microvascular diseases. The lipid accumulation product (LAP), visceral adiposity index (VAI), and Chinese visceral adiposity index (CVAI) are recognized tools for assessing visceral obesity. Retinal microvascular parameters serve as non-invasive biomarkers of systemic microvascular health, while qualitatively assessed urinary protein is a marker of early renal injury and endothelial dysfunction. Currently, evidence linking visceral obesity indices to retinal microvasculature is limited, and whether urinary protein status is associated with differences in this association remains unclear. This study aimed to investigate the associations of LAP, VAI, and CVAI with retinal microvascular parameters, and to explore differences in these associations between protein-positive and protein-negative individuals through stratified analysis. This study included 3,401 healthy individuals undergoing physical examinations. Participants were categorized into a positive group (n = 1,008) and a negative group (n = 2,393) based on their urine protein result. Demographic data, metabolic indicators, and retinal vascular parameters were collected. Spearman/Pearson correlation analysis was employed to explore the associations among these indicators. Multivariate linear regression analysis stratified by urine protein status was conducted to verify the independent association between the visceral obesity index and arteriole-to-venule ratio (AVR), as well as the differences between the groups Baseline characteristics revealed significantly higher levels of triglycerides (TG), LAP, and VAI in the urinary protein-positive group (all P < 0.05). Overall correlation analysis demonstrated that LAP, VAI, and CVAI were all inversely correlated with AVR (all P < 0.001). Stratified analysis indicated that the negative associations of LAP, VAI, and CVAI with AVR were more pronounced in the urinary protein-positive group. In multiple linear regression analyses, after adjustment for age and sex, LAP, VAI, and CVAI showed stronger negative associations with AVR and contributed more to the model’s explanatory power in the protein-positive group than in the protein-negative group. In fully adjusted models, these associations were attenuated but remained statistically significant, and the stronger effects in the protein-positive group persisted. Visceral adiposity indices are independently associated with retinal microvascular narrowing, and this association differs significantly between individuals with positive and negative urinary protein, with a more pronounced inverse relationship in the protein-positive group.