The value of ophthalmodynamometry as a diagnostic aid in carotid artery disease has been established and so have its limitations.1-6 The use of electroretinography for clinical evaluation of the carotid artery system was suggested by previous studies in animals7,8and in 1 human subject.9Granit demonstrated a selective disappearance of theb-wave during carotid compression in cats.7Theb-wave resumed a normal amplitude after release of the compression. Horsten and Winkelman showed a gradual, complete disappearance of thea- andb-wave in cats with carotid clamping for 7½ to 15 minutes.8After release of the clamp, both waves reappeared; however, these were sometimes of smaller amplitude than before clamping, suggesting permanent retinal damage. The greater sensitivity of theb-wave to retinal ischemia was suggested by the faster disappearance and slower reappearance. Kriz found a consistently larger ERG from the right eye