Rationale: Premature cardiovascular disease is a leading cause of death in patients with chronic kidney disease (CKD). In animal models CKD has been shown to cause renal and extrarenal vascular remodeling and capillary rarefaction, but data in humans with CKD are sparse. Retinal arteriolar wall-to-lumen ratio (WLR) is an established marker of early end-organ damage and there is evidence that arteriolar and capillary changes in the retinal circulation mirror those in the general and in particular the cerebrovascular microcirculation.
Objective: The aim of this study was to compare retinal capillary density and arteriolar structure between patients with CKD and healthy individuals.
Methods: We compared 76 patients with CKD stage 3+ or proteinuria >500 mg/g creatinine in the presence of a normal GFR from the German Chronic Kidney Disease cohort to 53 healthy control subjects, who participated in clinical trials during 2007 and 2015 in our Clinical Research Center. Retinal vascular parameters were measured non-invasively in vivo by scanning laser Doppler Flowmetry (SLDF, Heidelberg Engineering, Germany). Capillary rarefaction was assessed by intercapillary distance.
Results: Patients with CKD showed greater WLR (0.403 ± 0.11 vs 0.351 ± 0.11, p = 0.010) and greater wall thickness (WT) (15.1 ± 4.1 vs 13.5 ± 3.8, p = 0.026) compared to healthy individuals. Intercapillary distance (ICD) (22.4 ± 5.7 vs 20.2 ± 4.1, p = 0.008) was greater in the CKD group compared to the healthy control group. After adjustment for differences in clinical characteristics of the groups (age, gender, BMI, serum cholesterol) WLR (p = 0.046), WT (p = 0.025) and ICD (p = 0.003) remained significantly different between the two groups. There was a correlation between serum phosphate level and WLR in the CKD group (r = 0.288, p = 0.013).
Conclusion: Patients with moderately severe CKD show retinal signs of end-organ damage indicated by an increased wall-to-lumen ratio and capillary rarefaction.
Keywords: Capillary rarefaction; Chronic kidney disease; Microcirculation; Retina.
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