Effects of hypertension on the retinal vein width at the retinal arterio-venous crossings

Purpose. The study was designed to quantify retinal vein width changes at t he arterio-venous crossing and to evaluate the effects of hypertension on v ein widths at "vein posterior to the artery" (VPA) and "vein anterior to th e artery" (VAA) crossings. Methods. The width of the retinal veins was measured at points before and a fter the arterio-venous crossings by a computerized image analysis system i n ten normal subjects and 35 hypertensive patients. Retinal vein width chan ges at fixed intervals from the arterio-venous crossing points, both VAA an d VPA, were measured as a function of the stage of the hypertensive retinop athy in the subjects. Results. Mean retinal vein width showed significant (p < 0.05) narrowing at VPA crossings at stages 2,3 and 4 of hypertensive retinopathy. For the VAA crossings, there was no significant decrease in the width of the Vein at a ny stage. There was no significant narrowing of the vein at VPA crossings i n normal subjects or in stage 0 and stage I hypertensive retinopathy patien ts. Conclusions. The decrease in the width of the retinal vein in stages 2, 3 a nd 4 hypertensive retinopathy patients at VPA crossings can cause turbulenc e in blood flow, leading to intimal damage and occlusion. The absence of na rrowing may explain the low incidence of branch retinal vein occlusions at VAA crossings.