May 2004
Volume 45, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2004
Large Differences Between Japanese and US Students in Convergence Break and Recovery
Author Affiliations & Notes
  • M.K. Powers
    Gemstone Research Institute, Gemstone Foundation, Rodeo, CA
  • Y. Morita
    Gemstone Research Institute, Gemstone Foundation, Rodeo, CA
  • Footnotes
    Commercial Relationships  M.K. Powers, Gemstone Educational Mamagement F, E, P, R; Y. Morita, Gemstone Educational Management C.
  • Footnotes
    Support  none
Investigative Ophthalmology & Visual Science May 2004, Vol.45, 4327. doi:
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      M.K. Powers, Y. Morita; Large Differences Between Japanese and US Students in Convergence Break and Recovery . Invest. Ophthalmol. Vis. Sci. 2004;45(13):4327.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Abstract: : Purpose: To compare quantitative measurements of visual skills in Japan and US student populations Methods: Sixty–one students (average age 20 yrs) were screened for visual skills dysfunctions using a standard battery of tests that had previously been applied to US student samples in schools (average age 14 yrs), an optometric practice (average age 18 yrs), and a control sample (average age 23 yrs) reported last year at ARVO. Visual acuity, cover test, stereo acuity, and retinoscopy were included as well as near point of accommodation, accommodative facility, D.E.M. tracking, near point of convergence, and convergence/divergence ranges using a prism bar. Students also completed a symptom rating scale regarding their visual comfort while reading or studying. Results: Four students were omitted from the Japan sample (N=61) due to ocular disease or surgical history. 93% of the remaining 57 were female. 75% wore corrective lenses, and 93% (53/57) were 20/20 at near. Only 4 (7%) had phorias of 8 pd or more. 5.4% had stereo acuity worse than 40 sec. Some measures of visual skills were similar to US samples: DEM ratios were 1.14, accommodative facility was 12.3 cpm, and divergence ranges were 15.93 pd break and 11.33 pd recovery. However, convergence break and recovery were significantly higher, on average, than all US comparison groups: 35.67 pd (6.53 sd) and 30.84 pd (10.21) break and recovery, respectively. Near point of gross convergence (4.7 cm) and accommodative amplitude (8.6 cm) were lower than US values. Conclusions: The high values for convergence break and recovery may be related to the tendency toward myopia in this population. We speculate, in addition, that the fact that convergence is so strong may be related to vertical reading habits in Japan, compared to horizontal reading habits in the US.

Keywords: binocular vision/stereopsis • visual development 
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