| Popis: |
The value of visual evoked potentials (VEP) in the control and therapy of processes afflicting the visual pathways is not clear. The response can be altered by a number of factors which hinder an accurate interpretation (Barnett et al. 1980; Blom et al. 1980; Dustman and Beck 1969; Harter and White 1968; Hawkes and Stow 1981; Sokol et al. 1981). Such factors include check size, luminescence, visual field, state of refraction, and pupillary diameter. Their influence on the various VEPs — pattern reversal (PREP) and flash-evoked potentials (FEP), half- or full-field stimulation — is well known but difficult to distinguish from other influences, e.g., from pathological influences on the visual response. Differing results have therefore been published concerning especially the validity of side differences in localizing the pathological process. Some authors recommend VEP as the most sensitive procedure in the control of tumor patients, even in preserving visual acuity during operation (Feinsod et al. 1976). |
