Visual field is the range of space that can be seen without moving the eye and gazing forward at a point, and is the vision beyond the central macular sulcus. Visual field defect is the damage to the range of visual field. Visual field defect can be divided into the main conscious visual field defect and the visual field defect that cannot be consciously perceived. 1, the subjective visual field defect: (1) central, manifested as the presence of a fixed black spot in the center when viewing objects, such as macular lesions, macular retinal detachment, age-related macular degeneration. (2) Centripetal, manifested by the gradual reduction of the peripheral visual field when viewing objects, such as retinitis pigmentosa, optic nerve atrophy, and advanced glaucoma. (3) Directional, manifested as a sense of lamellar occlusion in a certain direction, such as retinal detachment, retinal branch artery obstruction, ischemic optic neuropathy, optic cross, optic path, and intracranial lesions. Among them, vertical hemianopia (the nasal or temporal half of the visual field is deficient with the point of gaze as the boundary) can provide a basis for the diagnosis of brain disease localization. 2, can not be consciously visual field defects: (1) physiological blind spot enlargement: seen in optic disc edema, optic discitis, optic disc with myelinated nerve fibers, etc.; (2) nasal step: glaucoma early visual field defects; (3) bowed dark spot: for optic nerve fiber bundle damage, seen in glaucoma, high myopia, optic disc vitreous warts, myelinated nerve fibers, ischemic optic neuropathy, etc. Because of the complementary binocular vision, monocular or mild visual field defects are often difficult to detect and should be detected promptly. Vertical hemianopia is extremely important for the localization and diagnosis of brain diseases. Characteristic visual field defects are also an important diagnostic basis for glaucoma, and the visual field should be reviewed every six months or annually if diagnosed as suspicious glaucoma.