Citation

Irsch K, Guyton DL, Ramey NA, Adyanthaya RS, Ying HS. Invest. Ophthalmol. Vis. Sci. 2013; 54(5): 3108-3114.

Affiliation

The Wilmer Eye Institute, The Johns Hopkins University School of Medicine, The Johns Hopkins Hospital, 600 North Wolfe Street, Wilmer 233, Baltimore, MD, 21287-9028, United States.

Copyright

(Copyright © 2013, Association for Research in Vision and Ophthalmology)

DOI

10.1167/iovs.12-11368

PMID

23572100

Abstract

PURPOSE: To document the cyclovertical ocular motor mechanism used for vertical fusion in normal subjects, and to explore whether vertical vergence training in normal individuals can produce objectively confirmed vertical deviations that change with head tilt, revealing a basic mechanism that can produce a pattern of misalignment in an otherwise normal ocular motor system that is similar to superior oblique muscle paresis (SOP). METHODS: Seven subjects with normal orthoptic exams were adapted to vertical image disparities using our tilting haploscopic eye-tracking apparatus presenting concentric circle targets without torsional cues. Static eye positions were recorded with head straight and when tilted 45 degrees to the left and right, during both binocular and monocular viewing. RESULTS: Vertical fusional vergence was accompanied by a cycloversion, with the downward-moving eye intorting and the upward-moving eye extorting, implicating primary involvement of the oblique extraocular muscles. After adaptation to the slowly increasing vertical target separation, all subjects developed a temporary vertical deviation in the straight ahead position that increased with head tilt to one side and decreased with head tilt to the other side. CONCLUSIONS: These results not only show that head-tilt-dependent changes in vertical deviation are not necessarily pathognomonic for SOP, but also, and more importantly, suggest mechanisms that can mimic SOP and suggest a possible role for vertical vergence training in reducing deviations and thus the amount of head tilt required for fusion. Ultimately, vertical vergence training may provide an adjunct or alternative to extraocular muscle surgery in selected cases.

Language: en