Extraocular muscles: Functional assessment in the clinic

S. P. Christiansen, L. K. McLoon

Research output: Chapter in Book/Report/Conference proceedingChapter


Humans have binocular vision, which means that there is overlap of a portion of the visual world perceived by each eye. The binocularity of human vision requires that the position of the eyes to be carefully controlled such that the same part of the visual field falls on corresponding parts of the retina of each eye. If the eyes are misaligned, objects in visual space will be focused on noncorresponding retinal elements. In normal individuals, such retinal image disparity initiates a motor fusional readjustment in the alignment of the eyes to reestablish binocularity. If this fails, then the adult experiences diplopia. Infants and children typically do not experience diplopia because they suppress the image from the deviating or nondominant eye. This places them at risk for amblyopia, a nonorganic loss of vision that may be permanent if not treated successfully during the time of visual plasticity in early childhood development. Moreover, a loss of input from one eye during a critical period for visual cortical development, typically during the first 3 months of life, will result in the permanent loss of binocularly driven cortical cells such that even if normal alignment can be reestablished, normal binocular function cannot. This signifies the important role of the ophthalmologist to promptly determine the nature of eye misalignment and attempt to correct this using a combination of glasses, patching, if appropriate, and surgery. This article will highlight the function of the extraocular muscles and the ocular motor system in health and disease followed by a stepwise approach to the treatment of strabismus.

Original languageEnglish (US)
Title of host publicationEncyclopedia of the Eye
Number of pages4
ISBN (Electronic)9780123742032
ISBN (Print)9780123741981
StatePublished - Jan 1 2010


  • Amblyopia
  • Binocular vision
  • Cover test
  • Diplopia
  • Esotropia
  • Exotropia
  • Inferior oblique muscle
  • Inferior rectus muscle
  • Lateral rectus muscle
  • Medial rectus muscle
  • Nystagmus
  • Strabismus
  • Superior oblique muscle
  • Superior rectus muscle

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