What is the pathophysiology of diplopia?

Updated: May 21, 2019
  • Author: Jitander Dudee, MD, MA(Cantab), FACS, FRCOphth; Chief Editor: Andrew G Lee, MD  more...
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Answer

Binocular diplopia (or true diplopia) is a breakdown in the fusional capacity of the binocular system. The normal neuromuscular coordination cannot maintain correspondence of the visual objects on the foveae of the 2 eyes. Rarely, fusion cannot occur because of dissimilar image size, which can occur after changes in the optical function of the eye following refractive surgery (eg, LASIK) or after a cataract is replaced by an intraocular lens or because of aniseikonia, which represents a discrepancy in image size perceived by the two eyes.

The distortion of one image may be interpreted as diplopia by the patient; however, the same object does not appear to be in 2 places but rather appears differently with each eye.

Monocular diplopia may result from abnormal light transmission to the retina (eg, corneal distortion or scarring, multiple openings in the iris, cataract or subluxation of the natural lens or pseudophakic lens implant, vitreous abnormalities, retinal conditions). Monocular diplopia must be distinguished from metamorphopsia, in which objects appear misshapen.


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