In a previous report1 a difference was described between the electromyographic pattern of version and convergence movement. The version, or saccadic, movement was shown to be associated with a sudden short discharge of larger motor units immediately followed by a regular pattern of lower amplitude. Corrective secondary bursts are often introduced upon this consistent discharge. Convergence is accompanied by a gradual increment of motor units and succeeded by a prolonged decrement. Alterations in the firing rate are slow in nature, and secondary adjustments are not seen. More recent data has shown that the two patterns are often combined in certain vergence movements and that more subtle changes are found in the motor units.
Differences of opinion have been expressed as to the findings in asymmetric convergence. One group2 has found coactivity of the medial and lateral rectus of the stationary eye, while another3,4 described no alterations. It
MILLER JE. The Electromyography of Vergence Movement. AMA Arch Ophthalmol. 1959;62(5):790-794. doi:10.1001/archopht.1959.04220050052009