Overacting oblique muscles in exotropia: A mechanical explanation

H. Capo, R. A. Mallette, D. L. Guyton

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Patients with exotropia often show apparent overaction of the inferior and superior oblique muscles. Are the oblique muscles contracted, are they truly overacting, or does the eye flip up or down in adduction from the leash effect of a contracted lateral rectus muscle? Theoretically, if the mechanical limits or ocular rotations were circular or elliptical, rather than square or rectangular, we would expect a patient with exotropia to develop a vertical deviation in extreme gaze into the oblique quadrants, for the abducting eye would reach the mechanical limit, while the adducting eye would still be free to move up or down, giving the appearance of both inferior and superior oblique overaction. The circular or elliptical limits of ocular rotations were documented with tracings from slow-motion video recordings. Also, reduction of pseudo-overaction of the obliques in both eyes following unilateral surgery for exotropia was observed in three patients. The strabismus surgeon should be aware of this possible mechanism for pseudo-overaction of the obliques and should avoid oblique muscle surgery in this clinical setting.

Original languageEnglish (US)
Pages (from-to)281-285
Number of pages5
JournalJournal of pediatric ophthalmology and strabismus
Volume25
Issue number6
StatePublished - 1988
Externally publishedYes

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Ophthalmology

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