Vertical fusional vergence: The key to dissociated vertical deviation

Edward W. Cheeseman, David L. Guyton

Research output: Contribution to journalArticle

Abstract

Objectives: To test the previous findings of Enright that disparity- induced vertical vergence is mediated primarily by the oblique muscles, and to relate this normal eye movement pattern to the eye movement pattern seen in subjects with dissociated vertical deviation. Methods: Sixteen normal volunteers underwent 55 measurements of the cycloversion associated with prism-induced vertical vergence using an afterimage apparatus. A Vernier scale measured the direction and magnitude of the torsional shift that occurred with recovery of fusion on removal of a 3- or 4-prism diopter prism. Results: Of the 55 trials, the directions of torsional shift were consistent with the oblique muscles being the primary mediators of vertical fusional vergence in 51 (93%) (P = .03 using a binomial distribution). The mean ± SD value of torsional shift was 1.15°± 0.76°in the expected direction. Conclusions: Vertical fusional vergences in this study were produced primarily by the oblique extraocular muscles. The eye movement patterns of these vertical vergences in normal subjects are qualitatively similar to those seen in recordings of patients with dissociated vertical deviation. Dissociated vertical deviation thus seems to be an exaggeration of a normally occurring eye movement pattern. The cyclovertical component of dissociated vertical deviation may help stabilize the fixing eye by damping vertical nystagmus, while the accompanying hypertropia is an incidental and undesirable side effect.

Original languageEnglish (US)
Pages (from-to)1188-1191
Number of pages4
JournalArchives of ophthalmology
Volume117
Issue number9
DOIs
StatePublished - Sep 1999

ASJC Scopus subject areas

  • Ophthalmology

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