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KMID : 1011420150200030319
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Journal of Korean Ophthalmic Optics Society
2015 Volume.20 No. 3 p.319 ~ p.324
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The Evaluations of Phoria and AC/A Ratio by Watching 3D TV at Near
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Son Jeong-Sik
Kim Dong-Su
Kim Jung-Ho
Kim Jae-Do
Alaric Hamacher
Yu Dong-Sik
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Abstract
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Purpose: This study was designed to evaluate the changes of phoria and calculated AC/A ratio, and their recovery time points by watching 3D television (3D TV).
Methods: 50 subjects (male 30, female 20) of 20s to 40s ages who can watch 3D, were measured phoria using a Howell phoria card at 3 m for distance and 40 cm for near. The phoria was evaluated before watching 3D TV and every 10 minutes from starting of watching 3D TV for 30 minutes, and every 5 minutes after finishing of watching 3D TV for 30 minutes again.
Results: For the distance phoria during and after watching 3D TV, it was increased to more exophoria ?0.98±1.37 ? (prism diopters) after 10 minutes from starting of 3D TV watching (p=0.063) and increased to more exophoria ?1.00±1.28 ? after 30 minutes (p=0.024), and started to decrease after finishing of watching 3D TV and recovered to the level of before 3D TV watching (?0.78±1.11 ?) after 20 minutes (p=0.32) with comparing to phoria of before watching 3D TV (?0.80±1.12 ?). For the near phoria, it was also increased to more exophoria ?5.71±4.45 ? after 10 minutes from starting of watching 3D TV (p=0.000) and ?6.58±4.36 ? after 30 minutes (p=0.000), and started to decrease after finishing of watching 3D TV and recovered to the level of before watching 3D TV after 20 minutes (?4.34±3.67 ?) (p=0.32) with comparing to the phoria of before watching 3D TV (?4.36±3.66 ?). AC/A ratio was decreased from 4.92±1.17 ?/D for before 3D TV watching to 4.11±1.50 ?/D for after 30 minutes from starting of watching 3D TV (p=0.000), and increased after the end of watching 3D TV and recovered to the level of before 3D TV watching (4.93±1.18 ?/D) after 25 minutes (p=0.598).
Conclusions: During watching 3D TV at near, it showed a tendency of convergence insufficiency by decrease of calculated AC/A ratio as result that exophoria at near was higher increased than exophoria at distance. However, the increased exophoria at both near and distance was recovered to the level of base line after 25 minutes from the end of watching 3D TV. Through this study, it seems to need rational proposals of advice for watching 3D TV.
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KEYWORD
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3D TV, Phoria, AC/A ratio, Asthenopia, Exophoria
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