Fluid filled oculoplethysmography and carotid artery disease: imperfect but useful

Fluid filled oculoplethysmography (OPG) is a widely used method of assessing carotid stenosis but it has limitations in the detection of bilateral internal carotid artery lesions and of external carotid artery stenoses. In this study, 157 consecutive patients having carotid angiography and fluid filled OPG were assessed to determine the accuracy of the technique and define the sources of error. Haemodynamically significant stenosis (HDS) was defined as at least 50% stenosis of the internal carotid artery (ICA). Only the most severely stenosed side of the 35 bilateral HDS lesions was detected owing to the poor reliability of ear pulse delays. Eye/eye delays alone detected the most severely stenosed side in 82 of 98 patients with an HDS stenosis of one or both ICAs for a sensitivity of 84% a specificity of 71% (41/59) and accuracy of 79% (81/157). The measurement of ear/ear pulse delays for external carotid artery (ECA) stenosis had a sensitivity of only 15% (5/34). Ear/eye pulse delays detected none of the 35 patients with bilateral HDS ICA stenosis. Bilateral equal HDS ICA stenoses were a significant source of error. Stenotic disease was present in the aortic arch and branches (five patients) or the carotid siphon (eight patients) and in seven cases it resulted in an incorrect localization on OPG. There was no diagnostic relationship between the severity of delay and the presence of total occlusion. Chronic local eye pathology was present in 13 patients and did not affect the results of the OPG. We have ceased to use ear pulse measurements for routine assessment but continue to use the eye/eye delays in conjunction with a carotid doppler imaging system.