Flicker-ERG in macular disease problems of stimulus and recording

✍ Scribed by Jerry H. Jacobson; George Stephens

• Publisher: Springer-Verlag
• Year: 1964
• Tongue: English
• Weight: 622 KB
• Volume: 18
• Category: Article
• ISSN: 0012-4486
• DOI: 10.1007/bf00160601

✦ Synopsis

With 13 figures

In many clinical situations objective determination of macular function, as distinguished from total retinal function, by the electroretinogram, would be of great importance. The eventual visual outcome of many surgical procedures depends upon the macular function. In considering this problem, in 1956, we outlined what we thought to be the possible methods of "uncovering", as GRANIT had put it, from the blanket of overwhelming numbers of rods, the function of the photopic system, or cones. For the purpose of this paper, we will overlook those known and unknown exceptions to the generally accepted situation, and equate photopic system to that beginning its chain of neurons with the cones and the scotopic system to that beginning with the rods.

At that time we propounded the following possibilities:

A. Limitation of the area of the retina stimulated. This would mean utilization of a narrow pencil of light as the stimulus. Although ASHER (1951) had demonstrated the difficulties with this method, and shown, for example, that optical and/or neuronal spread of the stimulus and response were such that it was possible to obtain a representative ERG with a narrow pencil directed at the optic disc, GOURAS et al. (1962) recently did report a differential between central and peripheral response with a small stimulus source.

B. Utilization of known physiological differences between the photopic and scotopic systems. 1) Chromatic -utilization of the relatively greater sensitivity for the long end of the spectrum of the photopic system.