Quantitative analysis of retinal vascular changes in essential and renovascular hypertension

Abstract

To describe a quantitative analysis method for retinal vascular changes and to study retinal vascular changes in patients with mild essential or renovascular hypertension in relation to 24-h ambulatory blood pressure monitoring. A cross-sectional prospective study was performed in 10 patients with essential hypertension and nine with renovascular hypertension selected from the outpatient clinic (continuing medication) compared with eight age-matched normotensive control subjects. Fundal photography was performed in both eyes, preceded or succeeded (in random order) by 24-h ambulatory blood pressure monitoring. The fundus photographs were projected on a glass table and vascular morphometric variables were determined. Vascular density was evaluated using a stereological technique with a square grid overlay. The main outcome measures were arterial and venous diameters near the optic disc and at the first bifurcation, vessel length, angles of bifurcating arteries and veins, and peripheral arteriolar and venular density. Both the arterial and the venous diameter was larger in the essential hypertensives and the renovascular hypertensives compared with the controls. Vascular diameter was positively correlated with mean arterial pressure during the night and with the night : day mean arterial pressure ratio (a measure of nocturnal blood pressure decline). Venular density was decreased in essential hypertension only and was not correlated with blood pressure. Our quantitative retinal vascular analysis method detected an increased vascular diameter in both essential and renovascular hypertensives, which was related to night-time blood pressure and, in particular, to an attenuated nocturnal blood pressure decline. Vascular rarefaction in essential hypertension was not related to blood pressure and could influence the pathogenesis of essential hypertension.