Retinal Arterioles in Hypo-, Normo-, and Hypertensive Subjects Measured Using Adaptive Optics

Small artery and arteriolar walls thicken due to elevated blood pressure. Vascular wall thickness show a correlation with hypertensive subject history and risk for stroke and cardiovascular events.

The inner and outer diameter of retinal arterioles from less than 10 to over 150 μm were measured using a multiply scattered light adaptive optics scanning laser ophthalmoscope (AOSLO). These measurements were made on three populations, one with habitual blood pressures less than 100/70 mm Hg, one with normal blood pressures without medication, and one with managed essential hypertension.

The wall to lumen ratio was largest for the smallest arterioles for all three populations. Data from the hypotensive group had a linear relationship between outer and inner diameters (r² = 0.99) suggesting a similar wall structure in individuals prior to elevated blood pressures. Hypertensive subjects fell below the 95% confidence limits for the hypotensive relationship and had larger wall to lumen ratios and the normotensive group results fell between the other two groups.

High-resolution retinal imaging of subjects with essential hypertension showed a significant decrease in vessel inner diameter for a given outer diameter, and increases in wall to lumen ratio and wall cross-sectional areas over the entire range of vessel diameters and suggests that correcting for vessel size may improve the ability to identify significant vascular changes.

High-resolution imaging allows precise measurement of vasculature and by comparing results across risk populations may allow improved identification of individuals undergoing hypertensive arterial wall remodeling.