[Motor and sensory responses in fusion of vertical disparities in different convergence places].
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 degrees x3.2 degrees 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 degrees every 8 s. Distance viewing was tested with 1 degrees of convergence demand, near vision with 6-15 degrees 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 degrees ) and near (mean 2.39 degrees ). The motor component differed significantly between distance (mean 1.42 degrees ) and near (mean 2.13 degrees ). No difference in the sensory component was seen between distance (mean 0.26 degrees ) and near (mean 0.27 degrees ).


CONCLUSIONS
Vertical fusion capability increases with convergence. This increase is mainly due to an increase of the motor response.
Steffen
H
H
The Johns Hopkins Hospital, Department of Neurology, Baltimore, MD, USA.
Hara
N
N
Roberts
D C
DC
Zee
D S
DS
D000065:Accommodation, Ocular; D000328:Adult; D003290:Convergence, Ocular; D005133:Eye Movements; D006801:Humans; D013223:Statistics as Topic; D015357:Vision Disparity; D014796:Visual Perception