Critical analysis of the digitalized pulse timing oculoplethysmography.

To critically analyze the accuracy of the OPG/Zira unit in the diagnosis of significant carotid artery stenosis, 135 patients (270 carotid arteries) were reviewed in comparison with the biplane carotid arteriograms. For practical purposes the radiological findings were divided into two categories; the first category included patients with normal carotids or carotids with less than 40% stenosis and the second category included patients who had carotid stenosis of greater than 40% (significant stenosis). The 136 arteries with significant stenosis on the arteriograms had positive OPG (136/160); i.e., 85.0% sensitivity, 101/110 arteries had negative arteriograms and negative OPG; i.e., 91.8% specificity. There was 6.2% false positive rate (9/145) and 19.2% false negative (24/125). The overall diagnostic accuracy was 87.7% (237/270).