title: Effect of different stimulus configurations on the visual evoked potential (VEP).
abstract: The purpose of this study was to assess changes in the response profile of the pattern visual evoked potential (VEP) using three stimulus configurations simulating visual-field scotomas: central circular and central blank fields increasing incrementally in diameter from 1° to 15°, hemi-field, and quadrant patterns. Five visually normal adult subjects (ages 22-68 years) were tested binocularly at 1 m for each stimulus configuration on 5 separate days. A checkerboard test pattern (64 × 64 black-and-white checks, 85% contrast, 64 cd/m(2) luminance, 20 s of stimulus duration, 2-Hz temporal frequency) was used. The group mean VEP amplitude increased in a linear manner with increase in the central circular diameter (y = 0.805x + 2.00; r = 0.986) and decrease in central blank field diameter (y = -0.769x + 16.22; r = 0.987). There was no significant change in latency in nearly all cases. The group mean coefficient of variability results indicated that the VEP amplitude was repeatable for the different stimulus configurations. The finding of VEP response linearity for the circular stimulus fields, and repeatability for all stimulus configurations, suggests that the clinician may be able to use the VEP technique with the suggested test patterns as a rapid and simple tool for objective assessment for several types of visual-field defects for a range of abnormal visual conditions and special populations.
authors.affiliation: Department of Biological and Vision Sciences, SUNY State College of Optometry, New York, NY 10036, USA. nyadav@sunyopt.edu
authors.forename: Naveen K
authors.initials: NK
authors.lastname: Yadav
authors.forename: Diana P
authors.initials: DP
authors.lastname: Ludlam
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Ciuffreda
mesh_terms: D000328:Adult; D000368:Aged; D005074:Evoked Potentials, Visual / Q000502:physiology*; D006801:Humans; D008027:Light; D008875:Middle Aged; D011930:Reaction Time; D012607:Scotoma / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*; D055815:Young Adult