Alisa Sivak, MA(Ed), is Head of Knowledge Translation at the Centre for Contact Lens Research, in the School of Optometry and Vision Science at the University of Waterloo.
As Jake Sivak points out in this issue’s editorial, the prevalence of myopia is increasing significantly. Although this phenomenon has been noted in various countries,1-8 a number of recent studies have focused on the high prevalence of myopia in Asian countries, including Taiwan,9 Singapore,10 South Korea11 and China.12
The 2014 meeting of the Association for Research in Vision and Ophthalmology (ARVO) showcased additional research on the prevalence of myopia in Asia—and China in particular. These studies report similar risks for the development of myopia, including a higher prevalence of myopia in:
- Urban13 or higher income14 communities
- Those with a family history of myopia14, 15
- Females14, 15
- Those demonstrating higher school performance as measured by math scores,14 zealous study habits and poor reading posture15
Seang-Mei Saw (University of Singapore) and colleagues13 presented a retrospective meta-analysis of 49 population-based studies performed across Asia. The results included large variations in the prevalence of myopia across Asia, with the highest combined prevalence (47%) in Asians aged 20-29 years living in urban Asian communities.
Zhongqiang Zhou (Sun Yat-sen University, China) and colleagues14 reported a prevalence of 23% myopia in school children (mean age 10 years) in Shaanxi, a province ranking 14th in China in terms of per capita income — nearly double that calculated for Gansu (at 13%), a neighbouring province ranking 30th for per capita income and with a higher population density. The researchers concluded that socioeconomic status, math score and a family history of spectacle wear were the main predictors of myopia, and noted that the determinants of myopia in China are complex and remain poorly understood.
Yueqiu Gong15 (Capital Institute of Pediatrics, China) and colleagues reported that the prevalence of myopia in one district of Beijing was higher for girls (39% compared to 35% for boys) and increased with age: 37% in those aged 5-15 and 67% in those aged 11-15. A family history of spectacle wear was also considered a significant risk factor. A variety of study habits were also cited as potential risk factors, including incorrect reading posture, doing homework for more than four hours per day and studying for more than one hour at a time.
Finally, Ian Morgan16 (Australian National University, Australia and Sun Yat-sen University, China) and colleagues reported the results of a study providing “proof in principal” that increasing the amount of time children spend outdoors can have slow the development of myopia. Out of 12 schools in Guangzhou, some children were given an additional 45 minutes of outdoor activity, while other schools continued following normal procedures. Over three years, the control group showed a 40% incidence of myopia compared to 30% in the test group spending more time outdoors. The research team acknowledges that the effect size is small, but suggested that myopia control programs should focus on increasing time outdoors regardless, as it may be beneficial.
- Hammond C. Myopia prevalence in Europe: cohort effect of increasing prevalence not fully explained by higher educational levels. Invest Ophthalmol Vis Sci 2014;55:E-Abstract 1268.
- Hrynchak PK, Mittelstaedt A, Machan CM, et al. Increase in myopia prevalence in clinic-based populations across a century. Optom Vis Sci 2013;90:1331-41.
- Vitale S, Sperduto RD, Ferris FL. Increased prevalence of myopia in the United States between 1971-1972 and 1999-2004. Arch Ophthalmol 2009;127:1632-1639.
- Aldebasi YH. Prevalence of correctable visual impairment in primary school children in Qassim Province, Saudi Arabia. J Optom 2014;7:168-76.
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- Ziaei H, Katibeh M, Solaimanizad R, et al. Prevalence of refractive errors; the yazd eye study. J Ophthalmic Vis Res 2013;8:227-36.
- Malu K, Ojabo C. Refractive errors in patients attending a private hospital in Jos, Nigeria. Niger J Clin Pract 2014;17:106-11.
- Hashemi H, Khabazkhoob M, Jafarzadehpur E, et al. High prevalence of myopia in an adult population, Shahroud, Iran. Optom Vis Sci 2012;89:993-9.
- Lin LLK, Shih YF, Tsai CB, et al. Epidemiologic study of ocular refraction among schoolchildren in Taiwan in 1995. Optom Vis Sci 1999;76:275-281.
- Saw SM, Tong L, Chua WH, et al. Incidence and progression of myopia in Singaporean school children. Invest Ophthalmol Vis Sci 2005;46:51-57.
- Jung SK, Lee JH, Kakizaki H, et al. Prevalence of myopia and its association with body stature and educational level in 19-year-old male conscripts in Seoul, South Korea. Invest Ophthalmol Vis Sci 2012;53:5579-5583.
- Sun J, Zhou JB, Zhao PQ, et al. High prevalence of myopia and high myopia in 5060 Chinese university students in Shanghai. Invest Ophthalmol Vis Sci 2012;53:7504-7509.
- Saw S-M, Pan C, Dirani D, et al. Is myopia more common in Asians? A systematic review and meta-analysis. Invest Ophthalmol Vis Sci 2014;55:E-abstract 1912406.
- Zhou Z, Ma X, Yi H, et al. Factors underlying large differences in myopia prevalence among primary school children in adjoining provinces of western China. Invest Ophthalmol Vis Sci 2014;85:E-abstract 1914853.
- Gong Y, Zhang H, Lv Y, et al. Prevalence and associated factors of myopia in primary school students in Chaoyang district of Beijing, China. Invest Ophthalmol Vis Sci 2014;85:E-abstract 1914355.
- Morgan I, Xiang F, Zeng Y, et al. Increased outdoor time reduces incident myopia – the Guangzhou Outdoor Activity Longitudinal Study. Invest Ophthalmol Vis Sci 2014;85:E-abstract 1914904.