Accommodation on downward gaze.

A study was conducted with the purpose of examining the possible effects of vertical and horizontal eye movements upon accommodation. A special Badal stimulator was made which was vertically rotatable around the center of an eye. The stimulator was attached to the Three-Dimensional Optometer III (TDOIII), which could measure accommodation, eye movement, and pupil diameter simultaneously. The reliability of the TDOIII measurements of accommodation was checked by comparing with a stigmatoscope measurement. Three young males served as subjects. A small but definite near accommodation was measured dynamically in association with vertical eye movement. We believe this to be the first report of this finding. The amount of near accommodation with downgaze showed a tendency to decrease when the target was brought near.