The Evaluations of Phoria and AC/A Ratio by Watching 3D TV at Near

3D TV 근거리 시청에 따른 사위도와 조절성폭주비 평가

  • Received : 2015.07.22
  • Accepted : 2015.08.22
  • Published : 2015.09.30


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 $-0.98{\pm}1.37{\Delta}$ (prism diopters) after 10 minutes from starting of 3D TV watching (p=0.063) and increased to more exophoria $-1.00{\pm}1.28{\Delta}$ 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 ($-0.78{\pm}1.11{\Delta}$) after 20 minutes (p=0.32) with comparing to phoria of before watching 3D TV ($-0.80{\pm}1.12{\Delta}$). For the near phoria, it was also increased to more exophoria $-5.71{\pm}4.45{\Delta}$ after 10 minutes from starting of watching 3D TV (p=0.000) and $-6.58{\pm}4.36{\Delta}$ 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 ($-4.34{\pm}3.67{\Delta}$) (p=0.32) with comparing to the phoria of before watching 3D TV ($-4.36{\pm}3.66{\Delta}$). AC/A ratio was decreased from $4.92{\pm}1.17{\Delta}/D$ for before 3D TV watching to $4.11{\pm}1.50{\Delta}/D$ 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 ($4.93{\pm}1.18{\Delta}/D$) 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.


3D TV;Phoria;AC/A ratio;Asthenopia;Exophoria


  1. Hoffman DM, Girshick AR, Akeley K, Banks MS. Vergence-accommodation conflicts hinder visual performance and cause visual fatigue. J Vis. 2008;8(3):33.1-30.
  2. Lee SH, Kwon SC, Kim JH. Digital stereoscopy, 1st Ed. Seoul: Jinsaem, 2014;37-60.
  3. Howarth PA. Potential hazards of viewing 3-D stereoscopic television, cinema and computer games: a review. Ophthalmic Physiol Opt. 2011;31(2):111-122.
  4. Kang SH, Hong HK. In watching 3D stereoscopic display using the binocular disparity, the effect of pupillary distance of adults and children on the perception of 3D image. J. Korean Ophthalmic Opt Soc. 2011;16(3):299-305.
  5. Kim JH, Son JS, Park SJ, Kwon SC. Clinical consideration of visual fatigue on 3D images. J KICS. 2013;38C(11): 990-999.
  6. Kang JJ, Kang MH. A study for application of human factor in stereoscopic photography by 2D-3D converting technology. AURA. 2012;26:111-122.
  7. Park JJ, Li HC, Kim SW. Screen disparity and size perception function of various 3D stimuli. Journal of Broadcast Engineers. 2013;18(1):66-76.
  8. Herman S. Principles of binocular 3D displays with application to television. J SMPTE. 1971;80(7):539-544.
  9. Kim JH, Choi YS, Kwon SC, Son KC, Sohn CB, Lee SH. The Influence on changes of visual function by watching 3D images - focused on blink rate and accommodative response. INFORMATION. 2014;17(12B):6589-6597.
  10. Lim SW. A study on acceptance of broadcasting platform in the era of media convergence: Focused on the niche comparison of selection factors of users. PhD Thesis. Chungang University, Seoul. 2006;1-261.
  11. Kham KT, Lee JH. The effect of inter-pupillary distance on stereopsis. The Korean Society for Cognitive Science. 2003;14(3):37-49.
  12. Kim DS, Lee WJ, Kim JD, Yu DS, Jeong ET, Son JS. Change of Phoria and Subjective Symptoms after Watching 2D and 3D Image. J Korea Ophthalmic Opt Soc. 2012;17(2):185-194.
  13. Maeda F, Tabuchi A, Kani K, Kawamoto K, Yoneda T, Yamashita T. Influence of three-dimensional image viewing on visual function. Jpn J Ophthalmol. 2011;55(3):175-182.
  14. Kim JD. Clinical refraction and visual dysfuntion prescription, 3rd Ed. Seoul: Shinkwang, 2010;240-260.
  15. Kim DS. The effects of 3D images on the visual function. Master Thesis. Kyungwoon University, Gumi. 2011;1-84.
  16. DTV and video equipment portal TV4u. The resolution of the TV and the viewing distance, 2006. February 2006).
  17. Freeman J, Avons SE. Focus group exploration of presence through advanced broadcast services. Proceeding of the SPIE. 2000;3959:530-539.
  18. IJsselsteijn W, de Ridder H, Freeman J, Avons SE, Bouwhuis D. Effects of stereoscopic presentation, image motion, and screen size on subjective and objective corroborative measures of presence. Presence: Teleoperators and Virtual Environments. 2001;10(3):298-311.
  19. Sreenivasan V, Irving EL, Bobier WR. Effect of heterophoria type and myopia on accommodative and vergence responses during sustained near activity in children. Vision Res. 2012;57:9-17.
  20. Karpicka E, Howarth PA. Heterophoria adaptation during the viewing of 3D stereoscopic stimuli. Ophthalmic Physiol Opt. 2013;33(5):604-610.
  21. Lee SH. Understanding 3D images, 1st Ed. Seoul: Jinsaem, 2010;16-56.
  22. Ban JE. Effects of interpupillary distance and AC/A ratio on binocular fusion and depth perception. Master Thesis. Yonsei University, Seoul. 2002;1-51.
  23. Kim DH, Choi SH, Sohn KH. Visual fatigue prediction for stereoscopic video considering individual fusional characteristics. Journal of Broadcast Engineers. 2011;16(2):331-338.
  24. Kooi F, Toet A. Visual comfort of binocular and 3d displays. Displays. 2004;25:99-108.
  25. Yekta AA, Pickwell LD, Jenkins TC. Binocular vision without visual stress. Optom Vis Sci. 1989;66:815-817.
  26. Tsubota K, Nakamori K. Dry eyes and video display terminals. N Engl J Med. 1993;328:584.

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