Retinal capillary rarefaction is associated with arterial and kidney damage in hypertension

Abstract

Microvascular disease and rarefaction are key pathological hallmarks of hypertension. The retina uniquely allows direct, non-invasive investigation of the microvasculature. Recently developed optical coherence tomography angiography now allows investigation of the fine retinal capillaries, which may provide a superior marker of overall vascular damage. This was a prospective cross-sectional study to collect retinal capillary density data on 300 normal eyes from 150 hypertensive adults, and to investigate possible associations with other organ damage markers. The average age of participants was 54 years and there was a greater proportion of males (85; 57%) than females. Multivariate, confounder adjusted linear regression showed that retinal capillary rarefaction in the parafovea was associated with increased pulse wave velocity (β = - 0.4, P = 0.04), log-albumin/creatinine ratio (β = - 0.71, P = 0.003), and with reduced estimated glomerular filtration rate (β = 0.04, P = 0.02). Comparable significant associations were also found for whole-image vascular-density, for foveal vascular-density significant associations were found with pulse wave velocity and estimated glomerular filtration rate only. Our results indicate that retinal capillary rarefaction is associated with arterial stiffness and impaired kidney function. Retinal capillary rarefaction may represent a useful and simple test to assess the integrated burden of hypertension on the microvasculature irrespective of current blood pressure levels.

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1

OCT angiogram from a single eye, showing the four retinal depths (top): the superficial retinal plexus, the deep retinal plexus, the outer retina and the choriocapillaris. Bottom left shows the scan region (darker) overlaid on the broader retina. Bottom right shows the cross-section of the superior vascular plexus (SVP).

Figure 2

OCT angiogram of the left macula illustrating the regions of interest for retinal capillary density analysis. The central circular fovea region has a diameter of 1.5 mm, the parafovea ring reaches from 1.5 to 2.5 mm from the foveal center and the whole image is a 6 mm square centered on the fovea.

Figure 3

Scatterplots of foveal density against measures of hypertension mediated organ damage, including the unadjusted linear regression model fits (blue line) with the mean (grey area) and observed (red dashed lines) 95% confidence intervals. (a) Pulse wave velocity; (b) log (albumin–creatinine ratio); (c) estimated glomerular filtration rate (eGFR > 90 excluded), (d) boxplot comparing whole image density between groups classified by estimated glomerular filtration rate <  > 60).

Figure 4

Superficial macular OCT-A image samples demonstrating differences in capillary density. (a) High capillary density (foveal density 51.5) in a participant with normal vascular stiffness (PWV 8.8 m/s) and healthy kidney function (eGFR = 90 mL/min/1.73 m2). (b) Low capillary density (foveal density 21.7) in a participant with high vascular stiffness (PWV 12.2 m/s). (c) Low capillary density (foveal density 29.7) in a participant with impaired kidney function (eGFR = 29 mL/min/1.73 m2).