Diplopia or Double Vision
Eyes | Ophthalmology | Diplopia or Double Vision (Symptom)
Commonly known as double vision, diplopia is the simultaneous perception of two images of a single object that may be displaced in different ways such as horizontally, vertically, or diagonally in relation to each other.
Dipoplia can be classified in: binocular, monocular, temporary and voluntary.
Binocular diplopia manifests in double vision arising as a result of the misalignment of the two eyes relative to each other, such as occurs in esotropia or exotropia. In such a case while the fovea of one eye is directed at the object of regard, the fovea of the other is directed elsewhere, and the image of the object of regard falls on an extra-foveal area of the retina.
Monocular dipoplia is rarer and it manifests as being able to view with only one eye, or, where the patient perceives more than two images, monocular polyopia.
Temporary diplopia can be caused by alcohol intoxication or head injuries, such as concussion. If temporary double vision does not resolve quickly, one should see an ophthalmologist immediately.
Voluntary diplopia is when people consciously uncouple their eyes, either by over focussing closely (i. e. going cross eyed) or unfocusing. Also, whilst looking at one object behind another object, the foremost objects image is doubled (for example, placing ones finger in between ones face whilst reading text on a computer monitor). In this sense double vision is neither dangerous nor harmful, and may even be enjoyable.
It is usually the result of impaired function of the extraocular muscles, where both eyes are still functional when diplopia sets but they cannot converge to target the desired object. Diplopia is often one of the first signs of a systemic disease, particularly to a muscular or neurological process, and it may disrupt a person’s balance, movement, and/or reading abilities.