Interpretation of results of compression ophthalmodynamometry.

Abstract

SUMMARY Retinal artery pressure measurements were correlated with angiograms in 100 patients who underwent these studies for presumed carotid artery occlusive disease. Using 90% stenosis as the level of stenosis required to produce a hemodynamically significant obstruction toflow, we found a false-positive rate of 10% and a false-negative rate of 28%. We conclude that ophthalmodynamometry remains an effective screening tool. Asymmetric retinal artery pressure measurements indicate the high probability of a high-grade stenosis or occlusion of one artery, but negative measurements do not exclude the presence of significant carotid occlusive disease. In this study no patient with the combination of a significantly altered retinal artery pressure and a carotid bruit had an angiogram showing stenosis of 49% or less. Stroke, Vol 13, No 5, 1982 THOMAS AND PETROHELOS 1 were the first to call attention to the importance of measuring retinal artery pressures in patients with occlusion of the internal ca­ rotid artery. They found definite lowering of the ipsi­ lateral retinal artery pressure in 7 of 8 patients with carotid artery lesions and in 8 of 11 similar patients described in the literature. They concluded that the finding of equal retinal artery pressures does not ex­ clude impairment of the internal carotid artery blood flow, but if other reasons for inequality are excluded, unilateral lowering of the retinal artery pressure is strongly suggestive of occlusion in the internal carotid artery. The method of measurement of retinal artery pressures has been well described elsewhere by Hol­ lenhorst 2 and by Smith. 3 Kearns 4 has reviewed the oph­ thalmic findings in carotid artery disease and has con­ cluded that a unilateral, significantly low retinal artery pressure indicates stenosis of 90% or more and that the pressure is often 50% or less (diastolic and systolic) of the pressure of the normal eye. However, a significant number of patients with chronic stenosis of the internal carotid artery, even to the point of occlusion, will have equal retinal artery pressures in the two eyes, as a result of the develop­ ment of collateral circulation to the eye. Kearns 4 ob­ served that normal or equal retinal artery pressures do