الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The eye is the sensory organ of vision that transmits informations received by light falling on it into electrical signals which are transmitted to the brain via the visual pathways. Biological currents are very weak, so they must be amplified through electronics. The study of these electrical signals is very important to understand the mechanism of vision and to diagnose some retinal diseases. ERG represents the combined electrical activity of different cells within the retina. Primary open angle glaucoma is a chronic disease that, in its fully developed state, is easily recognized. However, as in many chronic diseases, the onset is insidious, making early diagnosis difficult. The early detection of damage to the visual system by glaucoma is important, because visual loss is usually permanent. Individuals at greatest risk for glaucoma must be identified so that appropriate observation is instituted. Although many methods have been introduced to assess visual function Summary glaucoma and in patients suspected of having glaucoma, electrophysiologic evaluation is very important. Pattern ERG is a useful technique for early diagnosis of the disease especially among subjects with ocular hypertension having good visual acuity and normal visual field. A marked loss of optic fibres not detectable clinically may occur before the development of visual field defects in glaucoma patients. Stereoscopic optic disc and nerve fibre layer photography have been advocated as more sensitive indicators of damage as well as other tests of visual functions including; colour vision, flicker perimetry, contrast sensitivity and recording of visual evoked potential and the pattern electroretinogram.