SymptomEyes & vision
Vision Loss: Sudden and Partial Loss of Sight
Vision loss means losing part or all of your sight in one or both eyes. When it happens suddenly, over seconds to days, it is a medical emergency, even if it is painless or brief. Common urgent causes are retinal detachment, a blocked artery or vein in the retina, stroke, acute glaucoma, optic neuritis, bleeding inside the eye and giant cell arteritis. Fast treatment can save sight. Gradual loss over months is usually from cataract, glaucoma or macular degeneration.
Also called: Loss of vision, blindness, sudden vision loss, partial vision loss, transient vision loss, amaurosis fugax
At a glance
- What it is
- Loss of all or part of the vision in one or both eyes.
- Sudden causes
- Retinal detachment, retinal artery or vein occlusion, stroke or TIA, acute glaucoma, optic neuritis, vitreous hemorrhage, giant cell arteritis.
- Gradual causes
- Cataract, glaucoma, macular degeneration, diabetic retinopathy.
- Key question
- One eye (eye or optic nerve problem) or the same side in both eyes (brain problem)?
- Action
- Sudden loss needs the ER or an emergency eye service the same day.
When to get help
Call 911 or go to the ER
- Sudden loss of vision in one or both eyes, even if it has come back
- A curtain, shadow or veil coming across your vision
- Vision loss with face droop, arm weakness, speech problems or sudden severe headache
- A painful red eye with blurred vision, haloes, headache and vomiting
- Vision loss after a head or eye injury, or a chemical splash
- Vision loss over age 50 with new headache, scalp tenderness or jaw pain when chewing
See a doctor within a day or two
- Blurred or dim vision in one eye with pain on moving the eye, developing over hours to days
- A sudden shower of floaters or flashes without vision loss
- Sudden wavy or distorted central vision
Book a routine appointment
- Gradual blurring of vision over months
- Increasing difficulty seeing at night or in dim light
What to do now
- Do not wait to see whether it improves. Sudden vision loss, even brief, needs the same day assessment.
- Call 911 or your local emergency number if vision loss comes with stroke signs or after an injury.
- Go to the ER or an emergency eye service for other sudden vision loss.
- Cover each eye in turn to work out whether one or both eyes are affected, and tell the doctor.
- Do not drive yourself.
Treatment for some causes, such as retinal artery occlusion, works only within hours.
Sudden vision loss in one eye
| Cause | Typical features |
|---|---|
| Retinal detachment | Flashes, new floaters, then a shadow or curtain spreading across vision; painless |
| Central retinal artery occlusion | Sudden, painless, severe loss, like a "stroke of the eye" |
| Retinal vein occlusion | Sudden blurring or patchy loss; linked to high blood pressure and diabetes |
| Vitreous hemorrhage | Sudden floaters, red haze or dark vision; common in diabetic retinopathy |
| Optic neuritis | Blurred or dim vision over hours to days, pain on moving the eye, faded colors; linked to MS |
| Acute angle-closure glaucoma | Severe eye pain, red eye, haloes, headache, nausea |
| Giant cell arteritis | Over 50, new headache, scalp tenderness, jaw pain on chewing; can cause permanent blindness |
| Wet macular degeneration | Sudden distortion or a dark patch in central vision |
Temporary vision loss (amaurosis fugax)
Vision in one eye goes dark or blurs, often "like a curtain coming down," then returns within minutes. It is usually caused by a small clot temporarily blocking a retinal artery, often from a narrowed carotid artery in the neck. It is a warning sign for stroke and needs the same urgent assessment as a transient ischemic attack.
Vision loss in both eyes
When vision is lost on the same side in both eyes (for example, the right half of vision in each eye), the problem is usually in the brain:
- Stroke or TIA affecting the visual pathways
- Migraine aura: temporary, with shimmering zigzags lasting up to an hour
- Pituitary tumor: loss of the outer side vision in both eyes, usually gradually
- Raised pressure in the skull: brief blackouts of vision when standing, with headaches
- Head injury
Gradual vision loss
Slow loss over months or years has different causes: cataract, open-angle glaucoma, dry macular degeneration, diabetic retinopathy and uncorrected refractive error. See diminished vision for these.
Partial vision loss patterns
- Central blind spot: macular degeneration, macular hole, optic neuritis.
- Peripheral (side) loss: glaucoma, retinal detachment, retinitis pigmentosa, stroke, pituitary tumor.
- Upper or lower half: retinal vein or artery branch occlusion, ischemic optic neuropathy.
- Patchy loss: diabetic retinopathy, vitreous hemorrhage.
How vision loss is diagnosed
An eye doctor or emergency team will:
- measure vision in each eye and test the pupils
- map the visual fields
- measure eye pressure
- examine the retina and optic nerve after dilating the pupils
- scan the retina with OCT, or use ultrasound if blood blocks the view
Further tests depend on the suspected cause: ESR and CRP blood tests for giant cell arteritis, brain MRI for optic neuritis or stroke, carotid ultrasound and heart tests for artery occlusion, and blood sugar and blood pressure checks.
Treatment
- Retinal detachment: urgent laser, freezing or surgery to reattach the retina.
- Retinal artery occlusion: treated as a stroke, with urgent assessment at a stroke center and prevention of further strokes.
- Retinal vein occlusion: eye injections for swelling, laser, and control of blood pressure, diabetes and cholesterol.
- Acute glaucoma: drops and medicines to lower pressure, then laser to prevent recurrence.
- Optic neuritis: often recovers over weeks; high-dose steroids may speed recovery; testing for MS.
- Giant cell arteritis: high-dose steroids started immediately, often before biopsy confirmation, to protect the other eye.
- Vitreous hemorrhage: treat the cause; surgery if blood does not clear.
- Stroke: emergency clot-dissolving or clot-removal treatment where appropriate.
Low-vision services, aids and rehabilitation help people whose vision does not fully recover.
Frequently asked questions
What causes sudden vision loss in one eye?
Common causes include retinal detachment, blockage of a retinal artery or vein, bleeding inside the eye, optic neuritis, acute glaucoma and giant cell arteritis. Each needs urgent assessment, and some, like artery blockage, need treatment within hours.
Is temporary vision loss serious?
Yes. Brief loss of vision in one eye that returns within minutes can be a warning sign of stroke, caused by a clot temporarily blocking blood flow. Go to the ER for assessment even if your vision is back to normal.
Can vision loss be reversed?
Sometimes. Retinal detachment repaired quickly, optic neuritis, vitreous hemorrhage and acute glaucoma treated early often allow good recovery. Vision lost to retinal artery occlusion, advanced glaucoma or stroke is often permanent, which is why speed matters.
Can stress cause sudden vision loss?
Stress does not usually cause true vision loss, though it can trigger migraine aura and central serous retinopathy, which causes blurred central vision. Sudden vision loss should never be put down to stress without an urgent eye examination.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Ophthalmology: Sudden vision loss; Retinal detachment; Central retinal artery occlusion
- American Heart Association/American Stroke Association: Management of central retinal artery occlusion scientific statement
- National Eye Institute: Retinal detachment
- NHS: Vision loss
- American College of Rheumatology: Giant cell arteritis