Double vision is a condition in which the sufferer can see two images of one object in front of him. This may occur in one eye, a condition called monocular diplopia, or it may only be present when using both eyes, a condition called binocular diplopia. An ophthalmologist should evaluate double vision, because it may signal a serious illness. Double vision also can cause a person to crash a vehicle or sustain a serious fall.
Astigmatism
Astigmatism, a condition in which an altered shape of the cornea--the transparent outer covering of the eye--causes vision difficulties, may be the cause of monocular double vision, according to the Merck Manuals Online Medical Library. Other conditions that alter the shape of the cornea also may be responsible.
Cataracts
A cataract, which is a disorder in which the lens of the eye become milky or cloudy, sometimes causes monocular double vision. Johns Hopkins Medicine explains that a dry eye can also lead to this type of double vision.
Cranial Nerve Damage
Several cranial nerves control the muscles of the eye. Damage or disease can cause these nerves to improperly signal the eye musculature, causing binocular double vision. Cranial nerve palsy, head trauma, stroke, cerebrovascular disease, brain tumor, multiple sclerosis, inflammation or brain aneurysm may be responsible for affecting the cranial nerves' ability to control the muscles that move the eye. Wernicke's syndrome, a condition in which chronic alcoholism has damaged the cranial nerves, sometimes is to blame for binocular diplopia, explains the Merck Manuals Online Medical Library. Over time, chronic conditions such as diabetes or poorly treated high blood pressure can lessen the blood flow to the cranial nerves, rendering them unable to correctly signal the muscles that control the eye.
Thyroid Conditions
Graves disease and other thyroid conditions are sometimes implicated in the development of binocular double vision, states Johns Hopkins Medicine. In Graves disease, the muscles that control eye movements are affected, with painful inflammation and swelling. This often brings about a change in the appearance of the eyes, with the sufferer appearing to stare or have protruding eyeballs.
Myasthenia Gravis
Individuals with myasthenia gravis may develop binocular diplopia and drooping of the eyelid, explains the Merck Manuals Online Medical Library. Double vision is usually intermittent in this condition. Myasthenia gravis causes muscle weakness, including the muscles controlling eye movement.
Botulism
Sudden onset of binocular double vision may be the result of a type of poisoning known as botulism, explains the Merck Manuals Online Medical Library. Other symptoms such as vomiting, difficulty breathing and speaking may also manifest within hours. Botulism enters the body through a wound or the eating of food containing the toxin. Botulism weakens and paralyzes the muscles, including those that control eye movements.
References
- “Nursing Health Assessment: A Critical Thinking, Case Studies Approach”; Patricia M. Dillon, D.N.Sc., R.N.; 2003
- The Merck Manuals Online Medical Library: Diplopia
- Optometrists Network: About Double Vision
- Johns Hopkins Medicine: Seeing Double? See a Doctor
