The 52-year-old Master He suddenly developed blurred vision in his left eye, and at first thought it was caused by his old age and presbyopia, so he was fitted with a presbyopic lens for correction. But in the next two months, Master He’s vision got worse and worse, and he also visited the ophthalmology department during that time, but it never got better until three days before he was admitted to the hospital, when he suddenly lost his sight and was found to have a meningioma growing in the posterior orbital tip of his left eye by an MRI scan of his head. The first reaction of many people is to “go to the ophthalmology department” when their vision suddenly deteriorates, just like Master He. In fact, brain tumor will cause intracranial pressure to increase, which will make the eye venous blood flow back to the brain poorly and cause bruising and edema, which will damage the visual cells on the retina in the fundus, resulting in vision loss, and in severe cases, the retina in the fundus will have dotted, linear, lamellar or even flame-like bleeding, blurred vision, and in more severe cases, blindness will be caused by compression of the optic nerve. Therefore, if ophthalmic treatment does not work, it is important to consider that a brain tumor may be at work. Many patients are diagnosed with intracranial tumors only when their vision is severely reduced, such as pituitary tumor, craniopharyngioma, saddle node meningioma, etc. When the tumor is already very large, the vision is obviously reduced. According to statistics, optic nerve atrophy occurs in up to 86%-97% of intracranial tumors admitted and treated by neurosurgery. This means that most patients do not have a good chance to recover their vision after surgery. If intracranial tumors can be detected when vision changes just appear, the treatment will be much better and the patient will maintain a high quality of life after surgery. The following signals should be taken seriously when they appear: 1. Visual impairment or visual field defect of unknown cause, even if there is no obvious fundus change, CT examination of head should be routinely performed, and further MRI examination should be performed for suspicious cases. 2.For patients with ocular muscle paralysis, CT examination of the head should be performed after excluding trauma, diabetes and inflammation. 3. In addition to ocular visual changes, other systemic symptoms, such as endocrine disorders and headache, often accompany the tumor. Many patients who experience vision loss accompanied by headache think they are suffering from eye fatigue and delay treatment. Therefore, when these symptoms appear, the presence of intracranial tumor should be suspected. 4. If there are abnormal symptoms such as tearing in the wind, good and bad vision, vertigo, facial numbness, hoarseness, etc., further examination is needed to exclude the possibility of brain tumor and other major diseases. 5. The main symptoms of brain tumor are headache, vomiting and vision loss. Other common symptoms include obvious memory loss, slower reaction, slurred speech or uncharacteristic agitation, irritability, even hallucinations, sudden tinnitus, deafness, drooping eyelids, vertigo, etc. Brain tumor should be alerted first.