ACCOMMODATION AND VERGENCE IN NORMAL AND ABNORMAL SUBJECTS.

A number of parameters of an interactive dual-feedback model of the accommodation and vergence system were calculated from experimental measurements in normal and symptomatic subjects as well as selected symptomatic subjects after three months of orthoptic therapy. It is found that only tonic accommodative level and the slope of the fixation disparity curve with accommodation open-looped clearly discriminated between the normal and the symptomatic subjects. Following therapy, three parameters showed changes that tended towards normal values. These were: tonic accommodative level and slope of the fixation disparity curves under open- and closed-looped conditions.