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Diplopia (double vision)

Diplopia definition

Diplopia is the medical term for double vision (or seeing double). Types of diplopia include:

  • Horizontal diplopia – Double vision where the two images are seen side by side.

  • Vertical diplopia – Double vision where one image is above the other.

  • Diplopia in one eye – Double vision that persists in one eye when the other eye is closed (also called monocular diplopia).

In all kinds of diplopia, one of the two images looks more prominent than the other. The less obvious image when seeing double is sometimes called the ghost image.

Diplopia can be a symptom of very serious health problems. See an eye doctor immediately if you begin to have double vision.

Double vision causes

Diplopia can be considered a condition itself or a symptom of an underlying condition. There are many possible causes of diplopia, including:

  • Strabismus – Being born with misaligned eyes (strabismus) is one of the more frequent causes of diplopia. This misalignment may be constant or intermittent. Subtle and intermittent strabismus is more likely to cause double vision than more obvious cases of eye misalignment.

  • Astigmatism – Uncorrected astigmatism is another common cause of diplopia. It is the primary cause of double vision in one eye. Correcting the astigmatism with eyeglasses, contact lenses or LASIK (or other refractive surgery) usually eliminates diplopia from astigmatism immediately.

  • Cataract – The development of cataracts can cause a number of vision problems, including double vision in one eye or both eyes. The only treatment for diplopia from cataracts is cataract surgery.

  • Keratoconus – This is a progressive eye disease that causes the cornea to bulge forward into a cone shape. Like uncorrected astigmatism, keratoconus frequently causes double vision in one eye.

  • Dry eyes – Diplopia can occur if your eyes become dry due to prolonged computer use or other reasons. Typically double vision due to dry eyes is temporary and intermittent and can be successfully treated with artificial tears.

READ MORE about dry eyes and digital eye strain.

  • Stroke, head injury, brain tumor, brain swelling or brain aneurysm – A head or brain injury, tumor, stroke or related condition can cause diplopia.

  • Cranial nerve palsies – Diplopia also can be caused by loss of function of one or more cranial nerves that control eye position and movement. Cranial nerve palsies can be caused by diabetes, stroke, head injury, tumors, multiple sclerosis, an aneurism (bulging of a blood vessel in the brain or elsewhere) or other serious health problems.

  • Fatigue and lack of sleep – Diplopia from fatigue and lack of sleep can be dangerous — especially when driving at night. Getting plenty of rest will usually eliminate this type of double vision.

  • Alcohol or recreational drugs – Check yourself. Take steps to get clean and sober if you have a problem.

  • Refractive surgery – In some cases, people experience temporary double vision when recovering from LASIK or other vision correction surgery. This type of diplopia typically goes away with time or can be eliminated with an enhancement procedure.

When you have diplopia, other symptoms that frequently occur along with double vision include:

READ MORE: Causes of double vision

Treatment of diplopia

If you suddenly experience double vision — with or without any of the other symptoms above — seek immediate medical attention or see an optometrist or ophthalmologist as soon as possible.

Treatment of diplopia requires the diagnosis and treatment of the underlying cause of the double vision.

For example, if your diplopia is due to strabismus, the best treatment may be vision therapy or strabismus surgery. But if it's determined that your diplopia is due to a cranial nerve palsy caused by diabetes or some other disease, treatment of that underlying medical condition is needed to eliminate seeing double.

Double vision can occur when the eyes look in separate directions because of cranial nerve palsies, strabismus or other reasons.

Some cases of double vision are difficult, if not impossible, to fix — particularly, diplopia caused by stroke or other underlying medical conditions that are difficult to manage. In these cases, you may need to learn to adapt to occasionally seeing double.

Your eye doctor may be able to help by prescribing glasses that have special prisms in the lenses to reduce the diplopia. Other options may include patching one eye for periods of time or prescribing special contact lenses.

READ MORE about treatment of double vision.

Remember: The sudden onset of diplopia could signal a condition that may be a matter of life and death, such as a brain tumor or aneurysm. See an eye doctor or seek medical attention immediately if you suddenly experience double vision.

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