Open a PDF version to print this topic

HealthInfo Canterbury

Vision loss in one eye


Loss of vision in one eye is an emergency. It can be caused by a blocked artery, which can be reversed if it is treated promptly, saving vision in that eye.

If you have lost vision suddenly, even if it's just been temporary and has now recovered, you must seek medical help from your doctor or optometrist.

You can lose vision in one eye for several reasons, some of which are potentially serious. This can be temporary and may only last a few minutes, but the causes may still be important and need treating. Unless you regularly lose vision temporarily during migraines, get your eyes checked straight away.

Ongoing loss of vision

It's best to seek help straight away if you have lost vision in one eye, even if just temporarily. But even if it was some time ago, you should seek medical help.

Time since vision loss

What to do

Why it's important

Last 12 hours

Call an ambulance

If it is a blockage, there is still a good chance the blockage can be reversed.

Last 12 to 24 hours

Call an ambulance or be driven by someone to see your doctor or optometrist

If it is a blockage, there is still a small chance the blockage can be reversed.

More than 24 hours ago

Arrange an urgent appointment with a doctor or optometrist for within the next 24 hours

If it is a blockage, the window for recovering vision has passed, but there is still the possibility that it is not a blockage.

There are many other treatable reasons for the vision loss.

Temporary or brief loss of vision

vision loss one eyeTemporary loss of vision in one eye, or loss of one half of vision, for a few seconds or minutes can be caused by a migraine or blocked blood vessel.

Blocked blood vessel

A common cause is a small clot that has blocked the artery and has now cleared. This is called a transient ischaemic attack (TIA). A TIA of the eye has a special name, amaurosis fugax. It is usually painless but it is serious as it means that you are at more risk of having a stroke.

If you're aged over 50 and are also having headaches, or scalp or jaw pain (for example, when you're chewing food), this could be because of giant cell arteritis. This is an inflammatory problem that affects blood vessels. Book an immediate appointment with your doctor or optometrist.


Your vision loss is probably caused by a migraine if:

If your vision did not recover completely, book an urgent appointment with your doctor or optometrist.

Otherwise, aim to see your doctor about the issue at a later stage.

Other causes

If your vision has got worse in one eye but is only partially affected, there could be an important cause. See your doctor or local optometrist.

Written by Canterbury optometrists. Adapted by HealthInfo clinical advisers. Endorsed by clinical director, Ophthalmology, Canterbury DHB. Last reviewed November 2019.

Page reference: 263981

Review key: HIVOE-263981