[Effects of visual optical stimuli for accommodation-convergence system on asthenopia].
OBJECTIVE
We investigated the effect on eyestrain of optical stimuli that we designed for accommodation and convergence systems.


METHODS
Eight female students were given optical stimuli for accommodation and convergence systems for 1.5 min immediately after 20 min of a sustained task on a 3-D display. Before and after the trial, their ocular functions were measured and their symptoms were assessed. The optical stimuli were applied by moving targets of scenery images far and near around the far point position of both eyes on a horizonal place, which induced divergence in the direction of the eye position of rest. In a control group, subjects rested with closed eyes for 1.5 min instead of applying the optical stimuli.


RESULTS
There were significant changes in the accommodative contraction time (from far to near) and the accommodative relaxation time (from near to far) and the lag of accommodation at near target, from 1.26 s to 1.62 s and from 1.49 s to 1.63 s and from 0.5 D to 0.65 D, respectively, and in the symptoms in the control group after the duration of closed-eye rest. In the stimulus group, however, the changes of those functions were smaller than in the control group.


CONCLUSIONS
From these results, we suggest that our designed optical stimuli for accommodation and convergence systems are effective on asthenopia following accommodative dysfunction.
Department of Ophthalmology, University of Occupational and Environmental Health, Kitakyushu, Japan.
Tsuneto
T
Iwasaki
Akihiko
A
Tawara
Nobuyuki
N
Miyake
D000065:Accommodation, Ocular / Q000502:physiology*; D000328:Adult; D001248:Asthenopia / Q000503:physiopathology*; D003290:Convergence, Ocular / Q000502:physiology*; D005260:Female; D006801:Humans; D010775:Photic Stimulation