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Ian Wong, Qisheng You, Alex LK Ng, Jonathan Chan, Bonnie NK Choy, Dan Zhu, Jimmy SM Lai; Prevalence and associations of myopia among primary school students in Hong Kong. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3380.
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Despite the reported epidemic and increasing trend of myopia worldwide, particularly in Asia, there is a paucity of data on the prevalence of myopia in Hong Kong. We therefore conducted this study to examine the prevalence of myopia among primary school students in Hong Kong.
This is a school-based cross-sectional study. Non-cylcoplegic auto-refraction, subjective refraction by an optometrist and partial coherence interferometry for axial length measurements were performed for all participated students. Structured questionnaire was sent to the parents to assess associated risk factors of myopia.
Six hundred and seventy four children (311 boys) with a mean age of 8.5 years (range: 6-13 years) from 4 primary schools in Sham Shui Po participated in the study. The mean spherical equivalent and axial length was -0.33 diopters (D), 23.42 mm and -0.31 D, 23.37 mm for the right and left eye respectively. The overall prevalence of myopia (defined as <-0.5D) was 32.4%. The prevalence of myopia significantly increased with age, from 13.5% for 7-year old group to 49.1% for 11-year-old group. (Fig.1) It is noteworthy that the overall prevalence of high myopia (defined as SE<=-6.0 D or axial length >= 26.5mm) in primary school students was 2.3%. The prevalence of high myopia also increased significantly with age, from 1.4% in 7-year-old group to 8.5% in 11-year-old group. Among students with myopia, only 44.2% of them wear glasses, and only 44.5% of the parents know their children have refractive error. In a binary logistic regression analysis, myopia was significantly associated with age (P<0.001), but not significantly associated with gender (P=0.50), age of initial exposure to electronic device (P=0.47) and length of time using electronic device (P=0.59).
The prevalence of myopia in primary school students is high in Hong Kong as compared with western countries. There is a low awareness of myopia in parents and high proportion of no- or under-correction of myopia, suggesting a need for population education about myopia.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Figure 1. The prevalence of myopia in primary school students in Hong Kong increased significantly with age.
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