Symptom
Sudden vision loss
Medical emergency: seek care now
Clinically reviewed · Last reviewed 2026-06-13
Seek emergency care now if you have
- Sudden loss of vision in one or both eyes
- A dark shadow or curtain spreading across your vision
- Sudden vision loss with weakness, numbness or slurred speech
- Sudden painful vision loss with a red eye, halos or nausea
Possible causes
Sudden vision loss has several serious causes. Seek emergency care first; these are conditions to understand afterwards.
Retinal detachment Flashes, floaters and a shadow over vision; an emergency. Retinal artery occlusion Sudden painless severe vision loss from a blocked artery — an emergency. Retinal vein occlusion Blocked vein at the back of the eye causing sudden blurring or a dark patch. Optic neuritis Sudden blurred or lost vision in one eye, often with pain on eye movement. Giant cell arteritis Headache, scalp tenderness and jaw pain with vision loss in people over 50 — emergency. Glaucoma Acute glaucoma causes sudden painful loss with halos and nausea. Macular degeneration Wet macular degeneration can cause sudden central vision change. Diabetic retinopathy Bleeding in the eye can cause sudden loss in people with diabetes. Ocular migraine (visual aura) Migraine aura causes temporary disturbance that recovers, but new loss must still be checked.
Frequently asked questions
Is sudden vision loss an emergency?
Yes. Any sudden loss of vision, in one or both eyes and whether painful or painless, is a medical emergency that needs immediate care.
What should I do if I suddenly lose vision?
Seek emergency eye care immediately rather than waiting to see if it improves, as prompt treatment offers the best chance of protecting sight.
Can sudden vision loss come back?
Some causes, such as migraine aura, recover on their own, but you cannot know the cause without assessment, so sudden vision loss must always be treated as an emergency.