[Eyestrain induced by stereogram on 3-D display--differences between types of correction].
OBJECTIVE
We investigated eyestrain in normal subjects induced by gazing at a random-dot stereogram on a parallax barrier system 3-D display.


METHODS
The 41 subjects were divided into 4 groups according to the type of correction. Near point of accommodation, accommodative relaxation, and contraction times were measured with an accommodo-polyrecorder before and after a stereoscopic visual load, and 15 min and 30 min after a rest. The subjective symptoms were assessed by a 7-point rating questionnaire at the same time as the measurements.


RESULTS
After 15 min of sustained visual load, the near point of accommodation was prolonged significantly in the groups without correction and with soft contact lenses(SCL), and accommodative contraction and relaxation times were significant delayed in the groups without correction, with hard contact lenses(HCL), and with SCL but not in the group with spectacles. These changed values of accommodation returned to their previous value following the rest. Significant increase in the rating questionnaire was found in the subjective symptoms of "eyestrain", "eye heaviness", "clouding", "eye dryness" and "irritation of eyes" after loading in the groups without correction, with HCL, and with SCL. In the spectacle group, there was no significant change in the subjective symptoms of "clouding" and "eye dryness".


CONCLUSIONS
From these results, it is concluded that gazing at stereoscopic images on the parallax barrier system 3-D display causes severer eyestrain in cases of correction with contact lenses and in uncorrected cases than in cases with spectacles.
Department of Ophthalmology, University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka Yahatanishi-ku, Kitakyushu 807-8555, Japan.
Tsuneto
T
Iwasaki
Akihiko
A
Tawara
D000065:Accommodation, Ocular; D000328:Adult; D001248:Asthenopia / Q000503:physiopathology / Q000628:therapy*; D003261:Contact Lenses; D003263:Contact Lenses, Hydrophilic; D005139:Eyeglasses; D006801:Humans; D008297:Male; D015357:Vision Disparity; D014794:Visual Fields