The Retinal Vasculature and Risk of Age-Related GFR Decline - The Renal Iohexol Clearance Survey

Age-related decline in glomerular filtration rate (GFR) significantly contributes to chronic kidney disease (CKD). This longitudinal study in a nondiabetic population investigated whether retinal microvascular changes are associated with GFR decline.

The Renal Iohexol Clearance Survey (RENIS) included 1837 participants aged 50 to 62 years without self-reported diabetes, kidney or cardiovascular disease. Baseline retinal vessel measurements and retinopathy were assessed with a Visucam PRONM retinal camera. Iohexol clearance was measured over 1 to 4 visits across an 11-year median follow-up. Linear mixed models and logistic regression were used to analyze associations between retinal vessel measurements, retinopathy, mean annual GFR decline, and accelerated GFR decline.

In multiple adjusted linear mixed models, wider central retinal venular equivalent (CRVE) and wider central retinal arteriolar equivalent (CRAE) were associated with a steeper mean measured GFR (mGFR) decline. For each SD increase, CRVE was associated with an mGFR decline of -0.08 ml/min/yr (95% confidence interval [CI]:-0.15 to -0.02; P = 0.012), and CRAE was associated with a decline of -0.09 ml/min/yr (95% CI:-0.15 to -0.02; P = 0.007). CRVE, but not CRAE, was associated with accelerated mGFR decline in the model adjusted for age, sex, and height [OR 1.31 (95% CI 1.07-1.61, P = 0.008]. No significant associations were observed between retinopathy, microaneurysms, and hemorrhages with annual or accelerated mGFR decline.

CRVE and CRAE, but not retinopathy, retinal microaneurysms, or hemorrhages, were associated with steeper mean mGFR, suggesting that microvascular changes may be one of the underlying mechanisms for age-related GFR loss in a general nondiabetic population.