Sudden loss of vision is usually caused by eye strain or certain diseases. There are many reasons for sudden vision loss, the common ones are: 1, long hours of watching TV, reading cell phones, reading books, etc.. The eyes do not get rest, resulting in eye fatigue, often this will cause the eyes will slowly decline in vision, appear to see things blurred. 2, the elderly often due to retinal vein blockage and vision loss. 3. Acute angle-closure glaucoma can cause a sudden loss of vision, usually accompanied by rainbow vision (rainbow in front of the eyes), eye pain, nausea and vomiting. 4, retinal detachment will cause sudden vision loss, especially high myopia. 5.Diabetic patients can also experience vision loss when they have elevated blood sugar in the early stage. 6, A transient ischemic attack can lead to sudden loss of vision, but it can be recovered quickly. 7. A sudden and sharp increase in blood pressure can also cause a sudden loss of vision. 8, Acute eye diseases such as optic neuritis, optic nerve ischemia, central plasmacytoid retinopathy, wet age-related macular degeneration, vitreous hemorrhage, acute uveitis can lead to sudden vision loss. In short, sudden vision loss, to go to the hospital in time to check, so as not to miss the best time for treatment.