Prevention of scattered light-induced asthenopia and fatigue by a polarized filter.
BACKGROUND
It has been well documented that a long-time irradiation of the eye by a strong light elicits eyestrain and fatigue. To elucidate the mechanism for the induction of light-induced fatigue and asthenopia, changes in the mouse were analyzed after white light-irradiation to the eye.


METHODS
C57BL/6j male mice were irradiated with white light in a specially designed room equipped with four mirrors covering all areas of its four walls to elicit diffused reflected light, and changes in their plasma levels of cortisol, INF-gamma, interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta) were analyzed.


RESULTS
Irradiation of mice with scattered white light significantly decreased the motional activity of animals, suggesting the occurrence of fatigue. Biochemical analysis and enzyme-immunoassay revealed that the irradiation of mice significantly elevated the plasma levels of cortisol, IFN-gamma, IL-10 and TGF-beta. All these changes were not observed with mice irradiated with the light in a similar room not equipped with mirrors. These changes were successfully inhibited by a polarized glass filter but not by a non-polarized filter with a similar absorbance.


CONCLUSIONS
These observations suggest that irradiation of the eye by scattered reflected light stimulated a stress response via hypothalamo-pituitary-adrenal axis to enhance the secretion of cortisol from the adrenal grand and increase the plasma levels of cytokines.
Hiramoto
Keiichi
K
Department of Biochemistry and Molecular Pathology, Osaka City University Medical School, Abeno, Osaka, Japan. hiramoto@msic.med.osaka-cu.ac.jp
Yamate
Yurika
Y
Orita
Kumi
K
Jikumaru
Mika
M
Kasahara
Emiko
E
Sato
Eisuke F
EF
Tamura
Shinzo
S
Inoue
Masayasu
M
D000818:Animals; D001248:Asthenopia / Q000097:blood* / Q000209:etiology; D001522:Behavior, Animal / Q000528:radiation effects; D016207:Cytokines / Q000097:blood*; D005123:Eye / Q000378:metabolism; D005221:Fatigue / Q000097:blood* / Q000209:etiology; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism*; D008027:Light / Q000009:adverse effects*; D008297:Male; D051379:Mice; D010913:Pituitary-Adrenal System / Q000378:metabolism*
D016207:Cytokines; D006854:Hydrocortisone