Causes & Risk Factors of Double Vision

Double vision, or diplopia, occurs when one or both eyes send two mismatched images to your brain. The brain interprets this as seeing the same image twice, resulting in double vision. The causes and risk factors of double vision depend on the type of diplopia: monocular diplopia or binocular diplopia.

Monocular Diplopia Causes

• When double vision only occurs in only one of your eyes, you have monocular diplopia. Different cornea conditions can cause double vision, such as an irregular curvature of the front portion of the cornea, known as an astigmatism, or keratoconus, which happens when your cornea slowly thins and becomes cone-shaped. Ptergium occurs when the mucous membrane that lines the inner part of your eyelids thickens. This thickening reaches the cornea and causes double vision.

  Disturbances of your lens can also make you see double. When your lens becomes less translucent, you develop cataracts. A dislocated lens, either caused by an eye condition called Marfan's syndrome or eye trauma, occurs when the ligaments that secures the lens breaks.

  Other causes of monocular diplopia include swollen eyelids, a growth on an eyelid, dry eyes or an unsmooth retina surface.

Binocular Diplopia Causes

• Binocular diplopia occurs when your eyes are misaligned. If either eye is covered, the double vision disappears. Problems with your extraocular muscles---the muscles around the eyeball---can cause this type of double vision. Infection of the brain, stroke, brain tumor, multiple sclerosis and head trauma, especially the fracturing of the bones around the eye socket, can all affect the extraocular muscles.

  Disease can also affect your eye muscles and lead to double vision. Diabetes can cause problems with your eye's muscle movements. The neuromuscular disease Myasthenia gravis causes your muscles to weaken, including your eye muscles. The swelling and thickening of your eye muscles caused by Graves' disease can also explain your double vision.

Risk Factors

• If you have recently suffered a head or eye trauma, you are at risk for developing double vision. Since cataracts is associated with double vision, you are also at risk if you are older than 65 years of age, suffer from long-term diabetes, smoke, take steroid medications or receive radiation treatments. Double vision can be a symptom of a serious medical condition and endangers your everyday life. If you suffer from double vision, see your health care provider.