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B. Drobe, E. J. Seow, F. L. Tang; Clinical Evaluation of Working Distance in Caucasian and Chinese Adults: A Comparison Study in France and Singapore. Invest. Ophthalmol. Vis. Sci. 2007;48(13):962.
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© ARVO (1962-2015); The Authors (2016-present)
A previous study on French adults (Drobe B, et al. IOVS 2006;ARVO 47:E-Abstract 5861) has shown that working distances were significantly different with task and presbyopia but not with ametropia. The aim of the present study was to investigate differences in working distance between Caucasian and Chinese young adults and presbyopes wearing progressive addition lenses (PALs).
59 French (ages 45 to 71, SE -5.87 to +0.75 D) and 39 Singaporean Chinese presbyopes (ages 39 to 68, SE -8.00 to +1.12 D) as well as 22 French (ages 23 to 44, SE -6.62 to +0.75 D) and 21 Singaporean Chinese (ages 18 to 39, SE -7.87 to 0.62 D) non-presbyopes participated in this study. All presbyopes were wearing PALs of similar progression length (18 mm). All subjects performed 2 tasks: writing and reading on a desk while working distance was continuously recorded at 10 Hz using a Polhemus Fastrack system. Texts were in French for Caucasians and in English for Chinese. Results were analyzed in terms of working distance and relative working distance (working distance divided by forearm length).
Non-presbyopes worked significantly closer for both tasks as compared to presbyopes (332±53 mm vs. 384±48 mm, ANOVA p < 0.001). This difference remained statistically significant even for relative working distance (0.88±0.14 vs. 1.02±0.12, p < 0.001). Among presbyopic subjects, the value of near addition was of no influence. Ametropia, i.e. myopia or emmetropia, had no effect on working distances. The writing task was performed at closer distances than the reading task (356±52 mm vs. 380±55 mm, p < 0.001). Women worked closer than men (p < 0.01), but this difference was due to a greater forearm length in men. Ethnicity had no general influence on working distance, but post-hoc analysis showed that Chinese were reading closer than Caucasians (p < 0.05). Moreover, ethnicity had a significant effect on relative working distance (p<0.05); Caucasians were writing closer than Chinese when their forearm length was taken into account (0.91±0.13 vs. 0.98±0.14; p < 0.001).
In this multiethnic adult sample, working distance changed significantly with task, gender and presbyopia but not with ametropia and the value of near addition. Gender differences were due to a difference in body size between men and women. Asians read at a closer distance while at equal forearm length, Chinese tend to write at a further distance than Caucasians.
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