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Visual field losses and changes of the optic nerve disk are signs of optic neuropathy in glaucoma; psychophysical and electrophysiological tests can contribute to an early detection of glaucomatous optic neuropathy. Electrophysiological methods, like pattern electroretinogram (PERG) and visual induced cortical potentials can be useful in the diagnosis of glaucoma since they are compatible with the functions of retinal ganglion cells. A combination of psychophysical and electrophysiological examination methods contribute to an early diagnosis of glaucoma because they make it possible to study different aspects of visual functions. The results of psychophysical tests correlate to a greater extent than electrophysiological tests with defects in visual fields. Temporal, temporal-and-spatial contrast sensitivity and visual induced cortical potentials, whose changes are detected in the "preperimetric" stage of glaucoma, are the most sensitive parameters, while PERG changes later. Both the color contrast and light PERGs reduce in glaucoma. However, a significant correlation was detected only between the reduction of the color contrast PERG and visual field defects. A reduced sensitivity of dark and color channels of the retinal cone systems was also registered. Defects of color sensitivity are more pronounced and they precede the onset of light sensitivity changes. Defects of color and contrast sensitivity are an early sign of the progressing of optic neuropathy in glaucoma.