Visual field defect refers to the damage of the patient’s field of vision, and most of the causes of visual field defect are eye diseases, such as retinitis pigmentosa, glaucoma, retrobulbar optic neuritis, fundopathy, etc. In the early stage of visual field defects, patients may not have any obvious feeling due to mild symptoms, but as the disease progresses, patients may often feel as if there is a curtain covering part of the visual field in front of their eyes, which affects their vision. There are also dark spots in the visual field, which may be located in the center of the visual field or in the center of the field, close to the center of the visual field. Some patients may also have ring-shaped or bow-shaped dark spots, which may be accompanied by hemianopsia (i.e., half of the normal visual field is missing). It is recommended that patients with visual field defects be seen in a hospital for evaluation of their condition and treatment as prescribed by the doctor.