[Ear to retina time and ophthalmodynamometry after ligation of the common carotid artery in rabbits (author's transl)].

Unilateral ligation of the common carotid artery was performed in rabbits. Before ligation, immediately thereafter, and 6 weeks later the ophthalmic artery pressure was determined and at the same time a synchronous measurement of the ear to retina time was done on both sides. The results were statistically analyzed (Tables 1-4). Ligation of the right common carotid artery resulted in a highly significant difference in systolic ophthalmic artery pressure between the two eyes of 16.4 mm Hg, and in diastolic pressure one of 13.0 mm Hg. After ligation of the left similar pressure differences of (systolic) 17.8 mm Hg and (diastolic) 15.2 mm Hg were shown. During the following 6 weeks these differences decreased considerably, to 41.5% and 29.2% after ligation on the right and to 33.5% and 36.6% after ligation on the left. The ear to retina time was markedly prolonged on the side of the ligation. This resulted in a highly significant side difference of 0.42 s immediately after ligation on the right common carotid artery and 0.4 s immediately after ligation on the left side. After 6 weeks these differences were only slightly reduced, to 80% and 72.7% respectively. These animal experiments demonstrate clearly that an acute occlusion of one common carotid artery in rabbits can easily be diagnosed by ophthalmodynamometry as well as by synchronous measurement of the ear to retina time. In chronic occlusions determination of the ear to retina time is superior to pressure measurement. This is of particular interest since in these experiments an ophthalmodynamometric method was used that is much superior to the clinical method of ophthalmodynamometry.