What is diplopia or double vision?

In medicine, double vision is known as diplopia and is described as the simultaneous perception of two images of a single object. The two images may be offset from each other horizontally, vertically, or diagonally; they can also be rotated.


Diplopia is the result in most cases of incoordination in the movement of the extrinsic muscles of the eyeball, the group of muscles that controls eye movement. The two eyes are still functional but cannot move in a coordinated way to focus on an object.

Dysfunction of the extrinsic muscles of the eye can be caused by mechanical problems, alterations in the neuromuscular junction or problems in cranial nerves III, IV or VI, as well as in the visual cortex. The range of diseases and associated conditions is very wide, and includes ophthalmological, infectious, neurological, autoimmune, carcinogenic and some systemic diseases. For example:

  • abscesses
  • Diabetes
  • Drugs, for example fluoroquinolones and psychotropics
  • Brain tumor
  • anisometropia
  • Guillain Barre syndrome
  • keratoconus
  • Multiple sclerosis
  • Lyme's desease
  • orbital myositis
  • Sinusitis
  • Squint
  • Botulism
  • alcohol intoxication

Since diplopia can be a sign of a systemic disease, including neurological processes, it is advisable to see a doctor if it appears, especially if pain also appears. In addition to double vision, diplopia often affects the perception of balancecoordination of movements and other skills, for example reading.

types of double vision

Double vision classification is one of the first steps in diagnosing diplopia. The first great classification is to know if it is binocular or monocular, that is, to know what symptoms affect each eye separately and if double vision requires both eyes (binocular) or if it also appears with a covered eye (monocular).

  • Binocular: binocular diplopia occurs with both eyes open, if one of the two is covered it disappears. It is due to strabismus, both esotropic (inward) and exotropic (outward), when each eye receives the image in different parts of the retina. In children it is common for the brain to suppress the image of one eye, which is why diplopia is rare in childhood strabismus but common in adults.
  • monocular: Monocular diplopia is double vision with only one eye. There is also the monocular polyopia, which is the perception of double vision in each eye independently, which causes the perception of more than two images of the same object if both eyes are open. Monocular diplopia is much less common than binocular diplopia and is more often due to causes of a benign nature, such as keratoconus, subluxation of the eye lenses or in some cases of astigmatism. Serious causes include lesions in the anterior visual cortex.
  • Temporary: temporary binocular diplopia can be due to alcohol intoxication and the effect of psychoactive drugs, such as benzodiazepines, opioid drugs or some anti-epileptics. It can also be due to concussion and other mechanical causes.
  • volunteer: Some people are capable of voluntarily misaligning their eyes, for example by forcing the focus towards the center (crossed eyes), or by focusing on objects behind other closer objects. In these cases, diplopia does not represent any damage or problem.


The treatment of diplopia depends on the specific condition that is causing it, and in any case it is essential to diagnose and treat the underlying cause. Some general guidelines include eye exercises, covering one of the two eyes, correction with prisms or surgery in severe cases.

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