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Updated January 15, 2009

Definition: Diplopia is the medical term for double vision. Diplopia causes a person to see two images of the same object. There are primarily two types of diplopia: monocular and binocular.

  • Monocular: Double vision that affects only one eye. If one eye is covered, the double vision continues.
  • Binocular: Double vision that affects both eyes. If either eye is covered, the double vision stops.

There are many causes, such as various diseases of the eye muscles, or when various neurological and endocrine diseases (including myasthenia gravis, thyroid disease or diabetes) affect the nerves that control vision. In addition, stroke, aneurysm, brain tumor, swelling of the brain, cataracts and strabismus can cause double vision. It also may be caused by an injury to the head. It can be congenital (since birth) or acquired later in life.

Besides monocular and binocular disruption, double vision can be vertical or horizontal. Patients with vertical diplopia complain of seeing two diagonally displaced images, one atop the other. In horizontal diplopia the images appear side by side.

If you have diplopia, you should be evaluated by a medical professional to determine its cause. The underlying cause will determine how to properly treat the condition.

Also Known As: Double vision
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