What is Double Vision or Diplopia?

Diplopia is when you see two images of the identical thing. We can distinguish between two types of diplopia, namely, monocular, and binocular diplopia. Monocular diplopia happens when a patient experiences double vision when one eye is open, while double vision when both eyes are open means binocular diplopia. 

Diplopia (Double Vision)
Diplopia (Double Vision)


Of course, the first symptom is seeing double. Other symptoms associated with diplopia are headache, nausea, dizziness, pain (including when you move your eyes), and blurred or unclear vision in one or both eyes.


There are numerous causes that can result in diplopia.

Monocular Diplopia

Causes of monocular diplopia include undercorrected refractive errors (such as astigmatism), dry eye syndrome, corneal shape problems (such as keratoconus), retinal abnormalities, and cataracts.

Binocular Diplopia

There are many possible causes of binocular diplopia. A common cause of binocular diplopia is a squint or strabismus. Other conditions that can cause diplopia include thyroid dysfunction, stroke or transient ischemic attack, aneurysm, convergence insufficiency, diabetes, myasthenia gravis, brain tumors, cancers, multiple sclerosis, black eye, and head injury.

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Double vision is diagnosed by a cover test. If double vision disappears while covering either eye, this reveals binocular diplopia. If double vision disappears while covering the affected eye and returns when the unaffected eye is covered, the diagnosis is monocular diplopia. If the double vision is monocular, the issue is more likely to be with the eye than with the nerves. In case a patient has binocular diplopia, additional tests are performed, such as magnetic resonance imaging (MRI), computed tomography (CT) scan, and blood tests.


Treatment depends on the underlying condition, so it is important to visit a specialist and consult with them about what needs to be done to correct the cause.

Monocular Diplopia

For astigmatism, general treatment approaches include wearing corrective glasses or contact lenses which can often straighten the curvature and allow inbound light to pass through the eye. Another treatment approach for corneal issues is laser surgery which reshapes the cornea. For cataracts, surgery is usually the best choice. For dry eyes, a prescription for tear substitute eye drops will relieve symptoms. 

Binocular Diplopia

Treatments include wearing glasses, eye exercises, wearing an opaque contact lens, wearing an eye patch, and surgery of the muscles of the eyes to correct their positioning.


Diplopia can affect anyone; however, it is most frequent in people over 60 years old. In adults, in whom vision is already fully developed, diplopia oftentimes becomes a very disturbing symptom.