Retinal angiographic blood flowmetry is reduced in the ocular ischaemic syndrome

The aim of this study was to examine the use of quantitative fluorescein angiographic analysis as a means of estimating rates of perfusion of the retina in eyes with a circulatory deficit secondary to carotid artery stenosis. The study included 21 eyes with ocular ischaemic syndrome (OIS) and 20 control eyes from subjects with carotid artery stenosis but without signs of ocular ischaemia. Analyses of video fluorescein angiograms extracting time intervals for the time delay between specific phases of the angiogram were performed. Time delay was compared between groups and in relation to degree of carotid artery stenosis and ocular systolic blood pressure. Among the three flow indices of retinal perfusion (arteriovenous passage time 1 (AVP1), arteriovenous passage time 2 (AVP2) and venous filling time (VP)), those including the venous filling phase were significantly prolonged in the OIS group. Furthermore, AVP2 was delayed by 3 sec. in OIS eyes (16.6 sec. versus 13.6 sec. in controls). VP was 2.4 sec. longer in OIS eyes (11.5 sec. versus 9.1 sec.). We found a significant correlation between AVP2 and ocular perfusion pressure, but no correlation between the degree of carotid artery stenosis and any of the flow indices. In a patient population spanning a wide ocular systolic blood pressure range, angiography-based quantitative flowmetry demonstrated a difference between carotid artery stenosis patients with and without OIS and a correlation between flow and ocular perfusion pressure. While angiographic flowmetry proved effective in discriminating between groups of individuals, it can only be used to support the diagnosis of the ocular ischaemic syndrome in patients with extreme flow reduction.