الفهرس 
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Abstract
Great difficulties are encountered when an attempt is made to systematize data concerning visual pathways and relays, Specific as well as non specific visual projections may be distinguished, electro— retinogram and electro-oculogram have been developed to test electrophysiological activiLy at retinal level of visual pathway and their response are generated by large areas of retina and despite their values in measuring generalised dysfunction, there are number of conditions, namely those specifically affecting the macular region which can not be evaluated.
The visual evoked potential affords an accurate assessment of foveal function, the potentials recorded are indirect measures of the fovea, these potentials generated in the occipital cortex represent the end stages of visual processing elicited by appropriate stimulation of the ratina.
The visual evoked potential is one of several evoked potentials which can be recorded from scalp electrodes become lost against the back—ground of normal spontenous activity of the brain this problem was solved by Averaging techniques, Galambos and Davis (1943) and later Dawsan (1947) realized a convenient method of averaging by super — impositioning the responses in a photographic film.
After several years of design and development, the communications biophysics group of niassachsetts institute of technology constructed an evoked response detector and an average response computer in the later 1950’s, around 1962 special purpose computers became available commercially for signal averaging.
Many terms were used to describe it, (VER) visual evoked response, (EOP) evoked occipital potentials (CEP) cortical evoked potential (PEP) photopic evoked potential (VEOG) visual evoked occipitogram and (VECP) visual evoked cortical potential Perry and Childers (1969).