QUANTIFICATION OF RETINAL CAPILLARY DENSITY AND FLOW VELOCITY IN PATIENTS WITH ESSENTIAL-HYPERTENSION

Arterial hypertension is known to be an important risk factor for cere bral and cardiovascular disease. Previous studies in rats have demonst rated that changes in both capillary density and vessel diameter may c ontribute to increased vascular resistance in hypertension. In vivo st udies of human subjects with essential hypertension revealed a reducti on in the number of arterioles in the skin and conjunctiva; no other i n vivo data are available from other tissues. By means of a new imagin g technique, capillary density and capillary blood flow velocity can n ow be assessed in the human retina. We undertook the present investiga tion to determine whether patients with essential hypertension and onl y minor clinical retinal vascular alterations have decreased retinal c apillary density and altered capillary flow velocity. Seventeen hypert ensive patients with only minor retinal vascular alterations and 17 he althy volunteers matched for age were selected. All study participants underwent ophthalmologic examination and fluorescein angiographic stu dies by means of scanning laser ophthalmoscopy. Capillary density and capillary blood flow velocity in the perifoveal network were evaluated from the angiograms. The retinal microcirculation in the perifoveal c apillary network of hypertensive patients showed significant alteratio ns. Both the capillary density and capillary flow velocities were sign ificantly reduced compared with the control group. For the first time alterations of capillary blood flow and capillary density in a vascula r network very similar to that of the brain have been demonstrated in hypertensive patients in vivo. Further studies with this technique may help identify patients at high risk for cerebrovascular diseases.