Noninvasive techniques for assessing the effect of environmental stressors on visual function.
Visual acuity, a standard measure of visual function, is affected by a variety of physical and toxic stressors. In anesthetized animals, the acuity may be determined by the visual-evoked potential (VEP). We compared two evoked potential methods: the steady-state VEP, elicited with a fixed stimulus, and the sweep VEP, elicited by a dynamic stimulus. The steady-state VEP is a conventional electrophysiological technique for determining acuity, although its signal-to-noise ratio declines at high spatial frequencies and introduces a source of error for acuity determinations. Moreover, it is unsuited for repeated or rapid measurements. The sweep VEP is elicited by a dynamic stimulus which sweeps through a series of spatial frequencies. Response amplitude is measured with a sensitive, synchronous filter. The sweep VEP can be completed in as little as 10 s and may be used for repeated measures. On the other hand, waveform data is lost with the sweep VEP. The two techniques yield fairly similar acuity measures, generally agreeing within a factor of two.
Glickman
R D
RD
KRUG Life Sciences Inc., San Antonio, TX 78279-0644.
Rhodes
J W
JW
Coffey
D J
DJ
D000818:Animals; D004594:Electrophysiology; D005074:Evoked Potentials, Visual / Q000502:physiology; D008253:Macaca mulatta; D010775:Photic Stimulation; D013312:Stress, Physiological / Q000503:physiopathology*; D014785:Vision, Ocular / Q000187:drug effects*; D014792:Visual Acuity / Q000187:drug effects