If you lose your vision suddenly, you probably need to see an optometrist or ophthalmologist immediately. Sometimes you can lose your vision due to a problem that’s existed for a long time. You might not notice any symptoms until your vision is affected. This often goes unnoticed because sight lost in one eye can be compensated for by the other eye. Sudden vision loss can be caused by several factors. For example, occlusion, which is retinal vein or artery obstruction, can affect your vision. To receive the best results for retinal artery occlusion (uh-clue-jun) treatment, you need to be treated within 90 minutes from the time you first notice the symptoms. If you don’t feel any pain but have a history of nearsightedness or trauma, you could have retinal detachment, where the retina is not attached properly. Pain accompanied by a headache and a swollen optic nerve could indicate temporary arteritis (are-ter-I-tis), or swelling of the arteries. Other causes of vision loss can include AIDS, cataracts, glaucoma, diabetes, macular (mack-you-lar) degeneration, retinal detachment, and retinitis pigmentosa (rhet-in-I-tis pig-mint-o-sah). Any change in vision could be a sign of a serious condition, so see an optometrist or ophthalmologist when you experience vision problems.