Potential preventive effects of a new visual intervention for accommodative insufficiency and asthenopia due to sustained near task.

Background: The objective of this study was to experimentally investigate whether a new visual intervention with optical and binocular vergence demands prevents accommodative insufficiency and asthenopia after sustained periods of visual task.

Methods: Fourteen female students were given the intervention with optical and binocular vergence demands for 1.5 min immediately after 20 min of a sustained task on a three-dimensional display. Before and after the trial, their ocular functions were measured and their symptoms assessed. A new type of intervention was developed that can vary optical and binocular vergence demands. For control, the subjects rested with eyes closed for 1.5 min after the task instead of the intervention.

Results: In the control group, accommodative contraction time (from far to near) and accommodative relaxation time (from near to far) was delayed from 1.13 to 1.68 s and from 1.36 to 1.60 s, respectively, and the symptom of asthenopia increased after rest. In the intervention group, however, changes in those functions were smaller than those in the control group.

Conclusions: These results suggest that the new intervention with optical and binocular vergence demands is effective for the treatment of accommodative insufficiency that follows sustained periods of visual task, and consequently, the symptom of asthenopia induced by accommodative insufficiency may decrease.