extorsion (excyclodeviation)
Also called excyclodeviation, excyclotorsion
Extorsion is a rotation of the eye around its anteroposterior axis that turns the upper pole of the cornea toward the temple.1 The rotation of a single eye in this direction is called excycloduction, and the opposite rotation, toward the nose, is incycloduction.1
The inferior muscles are the excycloductors of the eye.1 Excycloduction is the primary action of the inferior oblique and the secondary action of the inferior rectus, and the superior oblique and superior rectus intort.1 A misalignment of the eyes around the same axis is a cyclodeviation, named right or left excyclotropia or incyclotropia for the eye involved, and cyclodeviations are mostly manifest.2
In paralysis of the superior oblique, the unopposed inferior oblique produces an excyclotropia.3 A residual excyclotropia after traumatic trochlear paralysis is the most frequent cause of an isolated symptomatic cyclotropia.3
More detail
Treatment of a symptomatic cyclotropia is surgical.3 After superior oblique paralysis, weakening an overacting inferior oblique corrects both the hypertropia and the excyclotropia, and tucking the paretic superior oblique tendon does the same when the inferior oblique is not overacting.3 An isolated excyclotropia needs an operation that changes torsion alone, and the Harada-Ito advancement and lateralization of the superior oblique tendon is the established choice.3
Sources (9)
- von Noorden and Campos, Binocular Vision and Ocular Motility, ch. 4
- von Noorden and Campos, Binocular Vision and Ocular Motility, ch. 8
- von Noorden and Campos, Binocular Vision and Ocular Motility, ch. 18
- American Academy of Ophthalmology. 2020. Pediatric Ophthalmology/Strabismus: Basic and Clinical Science Course. San Francisco: American Academy of Ophthalmology.
- Ansons, A.M. and Davis, H. eds. 2014. Diagnosis and management of ocular motility disorders. 4th ed. Oxford: Wiley-Blackwell.
- Noorden, G.K. and Campos, E.C. 2002. Binocular vision and ocular motility: theory and management of strabismus. 6th ed. St. Louis: Mosby.
- Rutstein, R. and Daum, K. 1997. Anomalies of Binocular Vision: Diagnosis & Management. St. Louis: Mosby.
- Rowe, F.J. 2012. Clinical orthoptics. 3rd ed. Oxford: Wiley-Blackwell.
- Von Noorden, G.K. and Campos, E.C. 2002. Binocular vision and ocular motility: theory and management of strabismus. 6th ed. St. Louis: Mosby.
Reviewed October 2026
Related terms
Nearby in the glossary
- esotropia
- exophoria
- exotropia
- extorsion (excyclodeviation)
- extraocular muscles