Effect of optical defocus on the steady state pattern reversal visual-evoked response.
The effects of optical defocusing with convex lenses on the amplitudes of pattern reversal visual-evoked response (PVER) were investigated. With the large check size and high-contrast pattern, PVER amplitudes showed a linear decrease in response to initial defocusing up to +5 to +6 dptr. As the degree of defocus increased, the PVER amplitude, though irregular, continued to show reliable, definite responses up to +25 dptr. With the intermediate check size and pattern contrast, PVER amplitudes displayed a linear decrease, but unlike the large-check/high-contrast condition, diminished to noise level after a defocus of greater than +4 to +5 dptr. From these results, we speculate that two phases in this function curve derive from the large-check/high-contrast condition: first, the contrast- or contour-dependent phase, and, second, the luminosity/movement-dependent phase.
Katsumi
O
O
Eye Research Institute, Boston, Mass.
Hirose
T
T
Sakaue
H
H
Mehta
M
M
Rosenstein
R B
RB
D000328:Adult; D000550:Amblyopia / Q000503:physiopathology; D015350:Contrast Sensitivity; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D008297:Male; D055095:Optics and Photonics; D010364:Pattern Recognition, Visual