Brain tumor, firstly, is caused by the gradual increase of volume, which leads to the increase of intracranial pressure and edema of the optic papilla, resulting in vision loss; secondly, is caused by the direct invasion of the optic pathway by the lesion, resulting in vision loss. If the intracranial pressure is corrected and the pressure on the optic pathway is lifted in time, the vision can be restored or will not continue to decline, but if the person is blind or close to blindness, even if surgery is performed, the vision is often not restored. Brain tumors with symptoms such as headache, dizziness and limb weakness are easy to attract attention, but some intracranial tumors such as pituitary tumors in the saddle area, meningioma, orbital tumors and ophthalmic artery aneurysms, etc., often have first symptoms other than headache and dizziness, but vision loss in one or both eyes and change in visual field defects, which are often misdiagnosed as glaucoma, amblyopia and other eye diseases. Restricted inward and downward movement of the eyes may suggest brainstem lesions; inability to see upward in both eyes suggests lesions at the midbrain vertex and the possibility of pineal tumors; involuntary shaking of the eyes often suggests cerebellar lesions, etc. Therefore, if vision loss occurs and no clear lesion is found in the eyes, and glasses cannot correct the vision, it is recommended to have a CT or MRI examination of the head to exclude brain tumors and other conditions to avoid delaying the best treatment period.