Any time you can distinctly see a duplicate or shadow of the primary thing that you’re looking at, you’re experiencing double vision.
Double vision typically affects both of your eyes at the same time, but will occasionally only impact one eye. Double vision in one eye is called monocular diplopia, and it can be very disorienting.
The causes of double vision in one eye can range from minor to severe. This article will cover everything you need to know about double vision in one eye, including the signs that you need to talk with a medical professional.
When you have diplopia in one or both eyes, you see two objects when you’re looking at one image.
If you only have double vision when both your eyes are open, you have double vision in both eyes, which is called binocular diplopia.
Double vision in both eyes can be caused by eye conditions, but it can also be related to injuries like concussions and head trauma.
If you can close one eye and still see double, you only have double vision in one eye. This is called monocular diplopia.
If you are only seeing double in one eye, the cause is most likely related to your eye itself (as opposed to a nerve or brain condition). Likely causes include:
Dry eye
Dry eye can be a temporary symptom of another condition, such as allergies. Dry eye can also be chronic. In this case, it’s referred to as dry eye syndrome.
When the surface of your eye isn’t getting lubrication from your natural tears, a blurred or “phantom” image in one eye is not unusual.
Astigmatism
Astigmatism refers to an imperfection of the curve of your eye’s lens or cornea. When the lens or cornea don’t have a perfect curve, you may experience a distortion or blurring of your vision.
If you have astigmatism in only one eye, you may experience double vision in just that eye.
Keratoconus
According to the American Academy of Ophthalmology, keratoconus (when your cornea thins and bulges out) is a condition associated with eye rubbing and eye injury. It also appears to be genetic.
The American Academy of Ophthalmology also describes that keratoconus usually appears in your late teens or early 20s. If you have it, you may experience double vision in just one eye.
Cataracts
Cataracts cause the lens that helps focus your eye to become cloudy. If you have a cataract in one eye, double vision in one eye may be an early indicator.
Pterygium
A pterygium is a noncancerous growth that is often shaped like a wedge. When you have a pterygium, your conjunctiva or mucous membrane grows into your field of vision.
This condition is usually not a cause for concern, and it can be removed if it interferes with your daily life. One of the symptoms of a pterygium is blurry or double vision in one eye.
If you have recurring monocular diplopia, your eye doctor will need to do a full eye exam to confirm your symptoms and identify the reason why.
The exam may start with your eye doctor asking you to look at an image and see if double or blurry vision occurs. You may then be asked to cover one eye and see if the symptom persists.
Your doctor will then do an eye exam and look at each part of your eye. This process will typically uncover if you have the beginning of a cataract, for instance, or if you have astigmatism.
If a physical examination of your eye doesn’t reveal why you’re experiencing double vision, you may need additional imaging (such as an MRI), a referral to a specialist, or a neurological exam to rule out other conditions.
The treatment for double vision in one eye will depend on what’s causing your symptoms. Possible treatments include:
- eye drops to lubricate your eyes and relieve dry eye symptoms
- corrective lenses to improve your vision if you have astigmatism
- surgery to remove cataracts or pterygium growths
- surgical treatment if you have advanced keratoconus
Seeing double in one eye can be a dizzying experience, but it doesn’t mean you need to panic.
This type of double vision can happen simply because your eyes are dry, which can be easily treated.
Recurring diplopia in one eye can be a sign that the surface of your eye has been compromised, causing refractive errors (including double vision).
The causes of double vision in one eye are typically simple enough for your eye doctor to find with a physical examination of your eye, and your treatment options will be determined from there.