Vascular crossing patterns in patients with systemic arterial hypertension

Aim: To identify the relationship of retinal arteries in a population with systemic arterial hypertension. Methods: High resolution, dilated, digitised, fundus photographs of consecutive patients with a history of hypertension requiring pharmacologic therapy seen on the Wills Eye Hospital Retina Service were analysed. Included were photographs of the temporal retinal vascular arcades in which media clarity permitted good visualisation of third-order retinal vascular bifurcations. Each first- and second-order arteriovenous (AV) crossing was then examined to identify anatomic patterns at the sites where veins and arteries crossed. Eyes in patients without a history of hypertension were used as controls. Results: Among the 71 patients (134 eyes), there were 430 first-order and second-order AV crossings, in which AV nicking was present at 126 sites. A retinal artery was located anterior to the retinal vein in 122 of the 126 sites (96.8%) at which AV nicking was noted, while nicking associated with the vein located anteriorly to the artery occurred in only 4 of 126 (3.2%) of AV crossings (p<0.001). An anatomical pattern of venous arching, or cascading of a retinal vein over a retinal artery, was noted predominantly when the vein was positioned anterior to the artery in both subjects and controls. Among the 43 venous arching sites in the study group, 41 (95.3%) demonstrated the retinal vein anterior to retinal artery (p<0.001). Conclusions: In patients with systemic arterial hypertension and hypertensive retinopathy, AV nicking of the retinal vein at the site of AV crossing is seen predominantly when the retinal artery lies anterior to the vein, but generally not when the vein lies anterior to the artery. The clinician should realise that when a retinal vein lies anterior to a retinal artery, the absence of AV nicking does not rule out more severe, chronic, retinopathic changes than observed with retinal arterial straightening only.