Diplopia causes you to see two images of one object. This condition is commonly called double vision. Typically, this vision problem is the result of an underlying condition. Identifying and treating the cause can help you recover your eyesight and stop other symptoms from occurring.

There are two types of diplopia: monocular diplopia and binocular diplopia. You can figure out the type of diplopia you have with a simple test. While the double vision is occurring, cover one eye. If the double vision disappears while covering either eye you have binocular diplopia. In monocular diplopia, the double vision goes away when the affected or “bad” eye is covered, and returns when the unaffected or “good” eye is covered.

Monocular diplopia is the result of a problem with one of your eyes. A problem within your brain or the nerves to your eyes may be the cause of binocular diplopia. Once your doctor identifies which type of double vision you have, they can start looking for the cause.

Monocular double vision occurs due to a problem with one eye and is less common than binocular double vision. Many people with monocular diplopia report that one of the images will be very clear, while the other will be faded or washed out.

Possible causesAdditional symptoms and information
severe astigmatismIrregular shape and curvature of your eye can cause blurred vision and double vision.
corneal shape changes (keratoconus)This vision problem occurs when the clear lining over the front of your eye (cornea) begins to grow thin and develop a cone-shaped bulge. This bulge can cause double vision, blurred vision, and sensitivity to light. Scars or swelling of the cornea can also cause vision changes.
cataractThe lens that covers your eye is normally clear, but a cataract causes it to grow cloudy and foggy over time. This can lead to vision problems, including double vision. Other problems with the position or shape of the lens can also cause double vision.
dry eyeYour eyes constantly produce lubricating fluids. These fluids make blinking or turning your eyes more comfortable. If there isn’t enough fluid, you may experience stinging, itching, and vision problems.
pterygiumThe primary symptom of this vision problem is a raised, fleshy growth on the clear tissues that cover your eyelids and eyeballs (conjunctiva). This growth is not cancerous. It is a rare cause of double vision and the problem only occurs when the growth covers the cornea.

Binocular diplopia will disappear if you shield one eye. Double vision occurs because the two eyes are not working together. People with this type of double vision will often report that the two images they see are equally clear.

Possible causesAdditional symptoms and information
nerve damageThe delicate nerves of your eyes are responsible for running information between your eyes and your brain. Any inflammation or injury to the nerves can cause double vision.
diabetesThis disease can cause nerve damage that may lead to double vision and permanent vision problems.
cranial nerve palsyThe cranial nerves run along the surface of your brain. Sometimes, these nerves can become paralyzed. When this happens, you may develop vision problems, including double vision. Diabetes and high blood pressure are common causes.
myasthenia gravisThis immune condition affects communication between nerves and muscles throughout your body. In the eyes, this can cause rapid fatigue. This weakness of the eye muscles can lead to double vision.
Graves’ diseaseThis immune system disorder is the result of an overactive thyroid. About 30 percent of people with this condition experience some type of vision problem.
strabismus (crossed eyes) This is a common cause of double vision in children. The muscles of the eyes have trouble working together. It leads to a variety of vision problems and can cause permanent vision loss. This problem requires the attention of an eye specialist in any child over 4 months old.

Double vision always requires a doctor’s evaluation to determine the cause. Double vision is a symptom of something abnormal going on within your eye, brain, or nervous system. The problem needs a complete evaluation in order to uncover the cause.

In many cases, the extra image you see in your field of vision is the result of a treatable condition. But any sudden changes in your vision require immediate medical attention.

Some conditions need urgent medical care in order to prevent permanent vision loss or life-threatening complications.

Each possible cause for double vision has potential complications. The causes of double vision can range from something easily correctable to something more complicated, such as a chronic disease.

Some people with double vision may experience nausea or vertigo because of the altered field of vision. Others may experience eye strain and sensitivity to light or sounds.

Life-threatening conditions such infections or brain tumors can cause double vision, but these cases are rare. In these cases, severe eye pain or headache often occurs along with visual changes. Any headache accompanied by vision changes is considered life-threatening and requires immediate medical care.

Diagnosing double vision as monocular or binocular is usually straightforward. Determining the cause may be more difficult. If you have double vision, your symptoms and vision experiences will aid in the diagnosis.

When you visit your doctor, they will take note of your symptoms and perform a few tests to look for additional vision problems. They will also likely conduct a brief test to diagnose the type of diplopia.

Once you have a diplopia diagnosis, the work of finding a cause begins. To do this, your doctor will likely perform three types of testing:

1) Take stock of your current state of health

You and your doctor may spend some time updating your health history. This includes:

  • A full history of your symptoms: Fully describing your vision problems to your doctor can help them eliminate possible causes and decide on what tests may be helpful. Be sure to let your doctor know of any unusual symptoms you’ve experienced, even if you aren’t sure they’re related to your vision problem.
  • Your personal health history: Your doctor may consider underlying factors like diabetes, thyroid problems, or neurological disorders that could be causing your vision problems.
  • Your family health history: If family members had vision problems or disorders that can lead to double vision, let your doctor know. These issues may be a good starting point for your own diagnosis.

2) Physical exam

A full physical exam can help your doctor find and identify possible causes for your double vision. This exam may include:

Before deciding on a treatment, it’s important you and your doctor find the cause of the vision problem. In many cases, vision issues can go away once you correct or treat the underlying issue.

The most common treatments for diplopia include:

  • Corrective lenses: Eyeglasses or special lenses may correct the vision problem. For example, prisms may be etched into the lenses of your eyeglasses to adjust your vision.
  • Eye patch or cover: Covering one eye may stop the double vision. While this may not be a long-term solution, an eye cover can help manage double vision until there is a more permanent solution.
  • Eye exercises: If your vision problem is the result of strained or weakened eye muscles, your doctor can provide you with “exercises” that can help you regain eye muscle strength. As the muscles become stronger, your vision issues should improve.
  • Surgery: Depending on the cause, you might require surgery to correct any physical issues. Also, people with issues like cataracts or problems within the eye likely will need surgery at some point. The surgery to correct that problem should also fix any double vision.

Learn more: 3 eye exercises for strabismus »

People with double vision often make a full recovery. Some people will recover with minimal treatment depending on the cause. Others may need more care, but still experience a full recovery once your doctor identifies the problem.

Once the underlying cause is treated, the double vision and any other symptoms you’re experiencing should go away. In a few cases, you’ll need additional treatment, but most efforts to treat diplopia are successful.

Some common causes of double vision can come back. These include cataracts and cranial nerve palsy. In these cases, it’s important you work with your doctor to identify the problem as soon as it starts so you can begin treatment if the vision problems return.