Sudden blindness (total or near-total vision loss) in one eye is a medical emergency.

In many instances, you have a short window of time for diagnosis and treatment to avoid permanent blindness. Temporary loss of vision may also be a warning sign of a serious problem, such as stroke.

Keep reading to learn what might cause temporary blindness in one eye and how it’s treated.

Temporary loss of vision can occur in one eye and sometimes both eyes. It’s usually a symptom of an underlying condition that’s causing insufficient blood flow to the eye, such as a blood clot.

The vision loss can last from seconds to minutes. It’s referred to in medical terms as:

  • amaurosis fugax
  • temporary visual loss
  • episodic blindness
  • transient monocular visual loss
  • transient monocular blindness

The most common cause of blindness in one eye is reduced blood flow.

The carotid arteries in your neck bring blood to your eyes and brain from your heart.

Sometimes plaque (fatty deposits) builds up on the walls of these blood vessels, reducing the amount of blood that can pass through them. Small pieces of this plaque can even break off and block blood flow.

The narrowing or blocking of blood vessels bringing blood to your eye can cause temporary blindness.

A blood clot could also cause blockage. A blood clot is a gel-like clump of blood that has coagulated from liquid to a semi-solid state.

If a blood clot blocks your retinal artery, it’s referred to as either a branch retinal artery occlusion or a central retinal artery occlusion.

Temporary vision loss (total or partial) can also be the result of:

Vasospasm can also cause temporary vision loss. This condition is the result of a restriction in blood flow from a sudden tightening of the eye’s blood vessels.

Vasospasm can be caused by:

  • strenuous exercise
  • sexual intercourse
  • long-distance running

Treating temporary loss of vision in one eye starts with the identification of the underlying medical condition.

For example, if blood clots triggered the blind eye, healthcare providers concerned about the possibility of a stroke may recommend:

  • medications to thin your blood, such as warfarin (Coumadin) or aspirin
  • medications to lower your blood pressure, such as beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin-II receptor antagonists, calcium channel blockers, and thiazides
  • surgery, such as a carotid endarterectomy, to clear the plaque in your carotid arteries

Your healthcare provider may also recommend lifestyle changes, including:

The risk for temporary vision loss due to reduced blood flow is higher for people who have a history of:

Loss of vision in one eye is often the result of reduced blood flow to the eye from the heart. It’s typically a symptom of an underlying condition.

A healthcare provider can identify the condition affecting your eye and recommend an appropriate treatment plan.

If you experience sudden blindness in one eye, seek emergency medical assistance. In many cases, prompt diagnosis and treatment can prevent permanent blindness.