Seeing two images of a single object is called diplopia. A simple test helps narrow down the cause: cover one eye at a time.
If double vision stays with one eye covered
This is monocular double vision, coming from the eye itself. Common causes include:
- Uncorrected astigmatism
- Cataract
- Dry eye
- Corneal problems such as keratoconus
If double vision goes away when either eye is covered
This is binocular double vision, meaning the eyes are not aligned. Causes include:
- Nerve palsies, sometimes linked to diabetes or high blood pressure
- Thyroid eye disease
- Myasthenia gravis
- Long-standing squint that has decompensated
- Stroke, aneurysm or head injury
Seek emergency care for sudden double vision, especially with headache, a drooping eyelid, a large pupil, weakness, numbness or difficulty speaking.
Treatment
Treatment depends on the cause. Options include updated glasses, prisms, treating the underlying condition, and sometimes eye muscle surgery.
Frequently asked questions
Can tiredness cause double vision?
Mild, brief doubling when very tired can happen with a small hidden squint, but new or persistent double vision should always be checked.
Will double vision go away?
Some causes, such as certain nerve palsies, improve over weeks to months. Your doctor will monitor you.
Sources
This article is for general information and does not replace an examination by an eye doctor. If you have symptoms, please book a consultation.