To study motor and sensory responses in vertical fusion at different angles of horizontal vergence in normal humans. Methods: The study included 12 normal subjects. A cross (+) extending 3.4 x 3.2°was presented dichoptically. Vertical disparity was introduced by changing the vertical position of the cross in front of one eye. The disparity was incremented by 0.08° every 8 s. Distance viewing was tested with 1 °of convergence demand, near vision with 6-15°convergence demand. Eye movements were recorded using three-axis search coils. Results: Vertical fusion capability was larger at near vision than at distance in 9 of 12 subjects. For the entire group, total vertical fusion capability (motor plus sensory response) differed between distance (mean 1.68°) and near (mean 2.39°). The motor component differed significantly between distance (mean 1.42°) and near (mean 2.13°). No difference in the sensory component was seen between distance (mean 0.26°) and near (mean 0.27°). Conclusions: Vertical fusion capability increases with convergences. This increase is mainly due to an increase of the motor response.
- Vertical fusion
ASJC Scopus subject areas