What Causes Double Vision?

16 Apr 2014

Double vision, or ‘diplopia’, is the perception of two images when only one is present. The additional image can appear horizontally, vertically; obliquely or even overlapping the object you’re looking at.

What causes double vision?

There can be any number of causes, and some are an indication of a potential dangerous neurological problem, which is why it’s vital to see your doctor as soon as possible and review your case to get appropriate treatment.


You see more than one object when you look at something – the additional image might overlap or be adjacent to the object, or it may depend on the way you you’re your head.


There are two types of double vision, and it’s important to figure out whether it is monocular or binocular – that is in one eye or in both.


In monocular diplopia, the double vision is caused by a condition within one or both eyes and does not resolve when one eye is covered.


In binocular diplopia, the eyes are misaligned. Each eye sees a single image when working alone, as when one eye is covered, but when both eyes are open the brain perceives two adjacent images.

How is the cause of double vision diagnosed?

A thorough evaluation with a detailed history of when it started; how long it lasts; any additional issues and a complete medical overview are required to ensure nothing nefarious is the cause.


Visual acuity in each eye will be measured, and perhaps an eye exam to look for any ocular or orbital abnormalities. Particular attention is paid to the pupils and eyelid position if a neurologic cause is suspected. When a life- or vision-threatening cause is suspected, time may be of the essence.

Treatment for double vision caused by refractive errors

Once the underlying cause has been determined, treatment can be tailored to the underlying cause.


Many causes of monocular diplopia stem from poor focusing of light by the eye, and treatment is aimed at correcting the underlying cause of the blur.


For example, refractive errors (myopia, hyperopia, astigmatism) can be corrected with laser eye surgery, dry eye with artificial tears and/or tear duct plugs, and cataracts (clouding of the natural lens) with surgery.


Other conditions that interfere with proper focusing of light include corneal warping or scars and retinal conditions. Treatments are tailored to the specific condition believed to be causing the blurred images.


Binocular diplopia, on the other hand, is more dangerous as the misalignment of the eyes can signal a life-threatening condition. Aneurysms, strokes, trauma, and cancers can interfere with the nerves that control the extraocular muscles (the muscles that move the eyes in different direction of gaze).


If you have double vision, your first visit should be to your doctor to determine the cause. If you need treatment of a refractive error like myopia, hyperopia or astigmatism, and don’t wish to be dependent on corrective eyewear, call Optilase laser eye clinic on +353 1 223 8821.

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