Role of the central field in disparity-induced vergence movements in strabismus.

Disparity-induced vergence movements (fusional movements) were analyzed in esotropic patients by calculating the time required for compensation of a prismatic correction of their angle of deviation. The effect of central and peripheral field stimulation on these movements was studied by masking the central or the peripheral field. Both the center and the periphery were effective in triggering disparity-induced vergence movements. The center even seemed to prevail over the periphery. It is concluded that in comitant esotropia motor fusion is present not only in the periphery but also in the center, if appropriately tested.