Summary

The clinical electroretinogram (ERG) is highly responsive to circulatory disturbances in the retina. In the investigation reported here, it was sought to ascertain whether the ERG would lend itself to clinical diagnosis of circulatory disorders central to the eye primarily, those disparities between the right and left ophthalmic artery blood flows which accompany occlusive disease of the carotid arteries. I t emerged that the ERG alone did not, as a rule, reveal any typical disparities as between the two eyes, even in acute unilateral occlusion of an internal carotid. A load test was therefore essential if the ERG potentials were to be serviceable as an index for comparison of the right and left ophthalmic artery circulations. A standardized method of examination called electroretino-dynamography (ERDG) was devised. I t involves elevation of the intraocular tension by mechanical compression of the eyeball during ERG recording. The two eyes are examined separately in identical manner. In tests of thirty-two normals the ERG b-wave showed a similar decline for both eyes, no significant disparity being demonstrable. The ERDG disparity ranged from zero to 10 per cent and averaged 4 per cent. Twenty pathologic cases eye disease and optic nerve lesions as well as cases of cerebral insult without carotid thrombosis exhibited somewhat larger disparities than the normals, the range being from zero to 15 per cent. Sixteen cases of occlusive lesions of the carotid proximal to the ophthalmic artery presented very substantial disparities, the b-wave declining more sharply on the side of the (most pronounced) circulatory obstruction. The ERDG disparity ranged between 11 per cent (one of the bilateral cases) and 56 per cent. On comparison with the results obtained by the ophthalmodynamometric method, electrotino-dynamography showed, in the normals, considerably smaller disparities (mean, 4 per cent) than did ophthalmodynamometry (systolic disparity averaging 10 per cent; diastolic, 8 per cent). In cases with occlusive lesions of the carotid artery, on the other hand, electroretino-dynamography consistently revealed much greater disparities (mean, 39 per cent) than did ophthalmodynamometry (systolic disparity, on the average, 20 per cent; diastolic, 16 per cent). Electroretino-dynamography is a more sensitive method than ophthalmodynamometry for the determination of inequalities in blood circulation as between the two ophthalmic arteries. Moreover, it has the advantage of being