Perimetry, Electro-Oculography, Electroretinography and visual evoked potentials practiced in Ophthalmology, are put under: contingencies, bound to the patient and the equipment itself. In Perimetry difficulties are proportional with the respect between patient and material. In visual Electro-Physiology, the identical problems are seen often amplified by the difficulties due to the setting of the data compilation. It is fitting to opt for a protocol giving in a minimum of time, a maximum of reproducible data of the state of visual functions. A good knowledge of Electro-Physiologie bases will enable the user to avoid lots of traps. The choice of material must come into considerations for the type price reliability and easy utilization. The ERG must be realized taking into account as best as possible, the problem bound to the patients' age. The recording of EOG enables, coupled with the ERG, a functional assessment and a prognosis in the Retinal disease. This examination is sensitive to mechanical, physical and physic factors. Whatever the choice VEP flash or pattern, the patients' age, child or adult, will be determinant in the choice of the method and analysis results. The VEP answer is lost in a wave of interfered results. The VEP should be amplified and taken out from this background sound, while keeping its maximal structure.