The blood circulation in the eye is of decisive importance for the type and shape of the electroretinogram (ERG). This fact has been established ever since physiologists started to record and study the action potentials of the retina. Occlusion of the arterial blood flow has been used by Granit (1933) as a means of studying the components of the ERG.Clinical investigations in a small series of cases (Karpe 1945) showed that thrombosis and embolism of the retina cause distinct changes in the ERG. After elec?roretinography had been adapted for use as a clinical routine method, Karpe (1949) subsequently demonstrated that the ERG may be supernormal in the presence of slight venous stasis. When, on the other hand, there is complete occlusion, a negative ERG is recorded, particularly when the central vein is blocked. With a highly negative ERG, i. e., a large a wave and a small b potential, the prognosis is poorer than with a supernormal ERG and with a normal or only slightly negative ERG, in which the b potential is still fairly large. In thrombosis of a venous branch, the ERG exhibits only inappreciable pathologic changes or none a t all. In embolism of the central retinal artery, a highly negative ERG is found from the onset, whereas embolism of a branch results in little or no negativity. These data regarding the changes in the ERG in circulatory disturbances of the retina are based on a fairly large clinical series. They were, however, published without any statistical analyses of the case material. *) Received February 19th 19555.
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