Effect of simulated octant visual field defects on the visual evoked potential (VEP).

everal previous clinical research studies1--6 have found he pattern visual-evoked potential (VEP) to be useful in etecting a wide range of visual-field defects objectively. n a previous study completed in our laboratory,6 circuar, annular, hemi-field, and quadrant absolute visual-field efects were simulated and assessed objectively for detecion and discrimination using the pattern VEP method. he results were clear and consistent, and thus encourging. The group mean VEP amplitude exhibited a linear ncrease (y = 0.805x + 2; R = 0.986) with increase in central ircular field diameter. In comparison, the group mean mplitude decreased linearly (y = −0.769x + 16.22; R = 0.987) ith increase in central blank field diameter for the annuar stimuli. Lastly, VEP responses were able to differentiate etween hemiand quad-defects. No significant change n latency was found with any stimulus configuration. All f the aforementioned categories of simulated visual-field efects were detected with excellent repeatability. Thus, hese findings suggested that the VEP could be used as an bjective technique to detect different types of visual field efects rapidly and reliably. However, none of the previus studies further simulated and tested visual-field defects maller than quadrants.1--6 Therefore, in the current study, ur checkerboard pattern test field was further divided into ight horizontally oriented, rectangular stimulus regions i.e., octants). Thus, the purpose of the present study was to ssess quantitatively the effect of simulated octant, bsolute visual field defects on VEP responsivity in a isually normal adult population. This avenue was purued to assess potential detectability of even smaller, imulated absolute visual-field defects than in previous nvestigations. w s t t