Exophoria

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Exophoria
Classification and external resources
ICD-10 H50.5
ICD-9 378.42

Exophoria is a form of heterophoria in which there is a tendency of the eyes to deviate outward.[1] During examination, when the eyes are dissociated by prisms, the visual axes will appear to diverge away from one another.[2]

Prevalence[edit]

Exophoria is particularly common in infancy and childhood, and increases with age.[3][clarification needed]

Cause[edit]

Exophoria can be caused by several factors, which include:

These can be due to nerve, muscle, or congenital problems, or due to mechanical anomalies. Unlike exotropia, fusion is possible in this condition, causing diplopia to be uncommon.

References[edit]

  1. ^ Allen, Edmund Turney (1899). The science of higher prisms. Harvard University: G. K. Hazlitt 6 Co., printer. p. 39. 
  2. ^ Grosvenor, Theodore (2007). Primary Care Optometry 5th Ed. Butterworth-Heinemann. p. 224. ISBN 978-0-7506-7575-8. 
  3. ^ Freier B E, Pickwell L D (1983). "Physiological exophoria". Ophthalmic and Physiological Optics 3: 267–272. doi:10.1111/j.1475-1313.1983.tb00613.x.