title: Simultaneous pattern reversal ERG and VER recordings. Effect of stimulus field and central scotoma.
abstract: The effects of the sizes of the stimulus field and of an artificially created central scotoma on simultaneously recorded pattern-reversal electroretinogram (P-ERG) and pattern-reversal visual-evoked response (P-VER) were investigated. With an increase in the stimulus field from 4 degrees X 4 degrees to 12 degrees X 12 degrees, the amplitude of the P-ERG increased steadily. The amplitude of the P-VER also showed an increase up to a stimulus field of 6 degrees X 6 degrees or 8 degrees X 8 degrees, but showed no increase with further expansion of the stimulus field. A central scotoma, created by placing a square of black paper at the center of the 12 degrees X 12 degrees stimulus field, was increased from 4 degrees X 4 degrees to 10 degrees X 10 degrees by 2-degree increments. Amplitudes of both the P-ERG and the P-VER decreased with increasing central scotoma size. The P-VER decreased significantly with a 4 degrees X 4 degrees central scotoma. Although both the P-ERG and the P-VER were influenced by the overall stimulus field and the central scotoma, there was a distinct difference in their behavior. The P-VER showed saturation above a certain stimulus field size and, with a central scotoma of 4 degrees X 4 degrees, much more reduction than the P-ERG, suggesting that the P-VER depends more on the macular area than does the P-ERG. The P-ERG also exhibited a substantial macular dependency, which, however, was not as great as that of the P-VER. The greater macular dependency of the P-VER compared to the P-ERG, as observed in our study, reflects the larger anatomic representation of the macula at the higher visual level.
authors.affiliation: Eye Research Institute of Retina Foundation, Boston, Massachusetts 02114.
authors.forename: H
authors.initials: H
authors.lastname: Sakaue
authors.forename: O
authors.initials: O
authors.lastname: Katsumi
authors.forename: M
authors.initials: M
authors.lastname: Mehta
authors.forename: T
authors.initials: T
authors.lastname: Hirose
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004596:Electroretinography; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D008297:Male; D009898:Optic Disk / Q000502:physiology*; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation; D011897:Random Allocation; D012160:Retina / Q000502:physiology