Effects of a visual task with cognitive demand on dynamic and steady-state accommodation.

Dynamic accommodative response before and after, and steady-state accommodation during, a visual task were measured using an infrared optometer to investigate the effects of psychological stress on accommodative facility. Increase in the post-task dynamic accommodation response time (for a near-to-far condition) was greater for a group of subjects given a mental task at a higher presentation speed. In addition the steady-state accommodation showed an inward shift under a closed-loop condition which was enhanced when computation time was decreased. However, an inward shift was not evident when the performance level of subjects increased following training. The relationship between psychological stress, cognitive demand and accommodative function is discussed.