Sudden blindness caused by prolonged cell phone watching may be caused by temporary eye ischemia, eye fatigue, central retinal artery blockage, and so on. 1. Temporary eye ischemia: temporary eye ischemia leads to temporary blindness, long time looking at the cell phone eye overexertion of the whole body blood redistribution, resulting in retinal ischemia, through the rest will be improved. 2. Eye fatigue: excessive long time looking at the cell phone triggered by eye fatigue, so the sudden vision is not clear, you can do some eye exercises on the eyes, usually can be more intake of food containing carotene. 3. Central retinal artery occlusion: Sudden blindness is mostly considered to be caused by central retinal artery occlusion, or fundus hemorrhage, resulting in vitreous blood or retinal detachment. If the symptoms of sudden blindness, you need to rush to the hospital emergency ophthalmology to confirm the diagnosis, under the guidance of the doctor for treatment.