November 1998
Volume 39, Issue 12
Free
Articles  |   November 1998
Effect of horizontal vergence on the motor and sensory components of vertical fusion.
Author Affiliations
  • N Hara
    Department of Ophthalmology, Kitasato University, School of Medicine, Kanagawa, Japan.
  • H Steffen
    Department of Ophthalmology, Kitasato University, School of Medicine, Kanagawa, Japan.
  • D C Roberts
    Department of Ophthalmology, Kitasato University, School of Medicine, Kanagawa, Japan.
  • D S Zee
    Department of Ophthalmology, Kitasato University, School of Medicine, Kanagawa, Japan.
Investigative Ophthalmology & Visual Science November 1998, Vol.39, 2268-2276. doi:
  • Views
  • PDF
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      N Hara, H Steffen, D C Roberts, D S Zee; Effect of horizontal vergence on the motor and sensory components of vertical fusion.. Invest. Ophthalmol. Vis. Sci. 1998;39(12):2268-2276.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract

PURPOSE: To compare motor and sensory capabilities for fusion of vertical disparities at different angles of horizontal vergence in healthy humans. METHODS: Eye movements were recorded from both eyes of 12 healthy subjects using three-axis search coils. The stimulus was a cross (+) (3.4 x 3.2 degrees , vertically and horizontally, respectively) presented to each eye with a stereoscopic display. Vertical disparities were introduced by adjusting the vertical position of the cross in front of one eye. The disparity was increased in small increments (0.08 degrees ) every 8 seconds. Viewing was defined as "near" if there was a horizontal disparity that elicited 6 degrees to 15 degrees convergence, depending on the subject's capability for horizontal fusion; viewing was defined as "far" at 1 degrees convergence. Maximum motor (measured), sensory (stimulus minus motor), and total (motor plus sensory) vertical fusion were compared. RESULTS: In 9 (75%) of 12 subjects the maximum total vertical fusion was more in near than in far viewing. The three who did not show this effect had relatively weak horizontal fusion. For the entire group, the motor component differed significantly between far (mean, 1.42 degrees ) and near (mean, 2.13 degrees). Total vertical fusion capability (motor plus sensory) also differed significantly between far (mean, 1.68 degrees ) and near (mean, 2.39 degrees ). For the sensory component there was no difference between between far (mean, 0.268 degrees ) and near (mean, 0.270 degrees ). As vertical disparity increased in a single trial, however, there was a small gradual increase of the contribution of the sensory component to vertical fusion. CONCLUSIONS: Vertical fusion capability usually increases with convergence. This increase is caused primarily by an increase in the motor component. There is a gradual but small increase in the sensory component as target disparity slowly increases.

×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×