Ophthalmic & Physiological Optics ISSN 0275-5408
EDITORIAL
Myopia: an epidemic of possibilities? Figure 2 shows the prevalence of myopia for adults between 25 and 54 years. There is a higher frequency in the younger participants, consistent with an underlying increase in prevalence. In contrast, prevalence in the US sample of Vitale et al.,1 shown for comparison, varies little with age. Note that the prevalence of myopia approaches 50% in the youngest participants of both samples, although the European data are based on a stricter criterion for myopia—at least –0.75 D compared with any myopia. Finally, I’d like to highlight the most puzzling aspect of the prevalence data reported by Vitale et al.1 The underlying data are from participants selected ‘based on a multistage probability sample design using oversampling within selected age and race/ethnicity subgroups to estimate prevalence.’ In other words, meticulous care was taken in the selection of subjects so that the two samples, acquired thirty years apart, may be compared. Figure 3 shows the data for white participants with two data points highlighted. Given the passage of 30 years, the 18–24 year old participants from 1971 to 1972 should be comparable to the 45–54 year old participants in the 1999–2004 survey. The prevalence of myopia is 16.5% higher in the latter group (46.2% vs 29.7%), an increase that I have difficulty reconciling. One explanation is that one-third of all cases of myopia develop after the age of 24 years, but this is inconsistent with clinical experience and the limited research in the area.8 50
Prevalence of myopia (%)
The increasing prevalence of myopia1 has attracted recent attention in the popular press.2,3 It represents a significant public health issue, particularly in the case of high myopia which is a major cause of visual impairment in some Asian countries.4 Just as a picture is worth a thousand words, a paper showing a dramatic increase in a disease can launch hundreds of research grant submissions. Those of us working in the myopia field love to cite these papers in our applications for funding. In this issue of OPO, Plainis and Charman5 present a careful critique of the factors influencing the comparison and interpretation of myopia prevalence data, including the methods used to measure refractive error, the threshold chosen to define myopia and the influence of changes in refraction with age.6 Setting aside the clear and dramatic increase in the prevalence of myopia in Southeast Asia, I’d like to focus on some data from the West to further demonstrate the challenges faced in interpreting prevalence data. Vitale et al. reported a dramatic increase in the prevalence of myopia in the US population from 25.0% in 1971– 1972 to 41.6% in 1999–2004.1 They analyzed data from the ongoing National Health and Nutrition Examination Survey (NHANES), a nationally representative survey. Participants are interviewed in their homes and subsequently undergo a comprehensive examination in a mobile center. Vitale and colleagues’ data for white participants are replotted in Figure 1. These data show, at first glance, a compelling increase in prevalence in the 30 years between samples, but we must remember that each line shows an age dependence that represents a combination of factors including a possible underlying increase in prevalence over time and the wellestablished increased prevalence with age. Compare the 18– 24 and 25–34 year age groups in the 1999–2004 sample. The prevalence is almost 8% higher among the older of these two groups. If the underlying prevalence were increasing, wouldn’t we expect a higher prevalence among younger participants? A higher prevalence of myopia among younger subjects associated with an underlying increase has been observed in other large-scale studies. For example, Williams et al. estimated the prevalence of myopia in European adults using data collected between 1990 and 2013 for 61 946 individuals from fifteen population-based cohort and cross-sectional studies.7 These data from the European Eye Epidemiology (E3) Consortium were combined in a random effects meta-analysis stratified by 5-year age intervals.
40
30
20 1999–2004
10
1971–1972
0 12–17
18–24
25–34
35–44
45–54
Age (years) Figure 1. Prevalence of myopia among white participants from the National Health and Nutrition Examination Survey data from 1971– 1972 and 1999–2004. Redrawn from Vitale et al.1
© 2015 The Authors Ophthalmic & Physiological Optics © 2015 The College of Optometrists Ophthalmic & Physiological Optics 35 (2015) 349–351
349
Editorial
M A Bullimore
Prevalence of myopia (%)
50
a steady flow of opportunities for clinicians and researchers alike. I’ll leave you with the observation that in Australia the prevalence of myopia is relatively low and appears stable.9 The Australian population, like those discussed above, is of predominantly European ancestry, thus there is hope that modifiable risk factors, such as time spent outdoors,10,11 may be identified leading to strategies to reverse the apparent epidemic in most parts of the world.12
40
30 US (NHANES)
20
Mark A. Bullimore University of Houston College of Optometry, Houston, TX USA E-mail address: [email protected]
Europe (E3) 10
0
25–29
30–34
35–39
40–44
45–49
50–54
Age (years) Figure 2. Prevalence of myopia in European adults in the European Eye Epidemiology (E3) Consortium. Redrawn from Williams et al.7 Data from the 1999–2004 National Health and Nutrition Examination Survey data are shown for comaprison.1
Prevalence of myopia (%)
50
40
30
20 1999–2004
10
0
1971–1972
12–17
18–24
25–34
35–44
45–54
Age (years) Figure 3. Prevalence of myopia among white participants from the National Health and Nutrition Examination Survey data from 1971– 1972 and 1999–2004. Redrawn from Vitale et al.1
In summary, we must continue to view data on the prevalence of myopia with a critical eye. Even the most carefully designed and conducted studies can result in more questions than answers. In spite of the qualifications iterated eloquently by Plainis and Charman5 the prevalence of myopia is likely increasing, so we can thus look forward to
350
References 1. Vitale S, Sperduto RD & Ferris FL 3rd. Increased prevalence of myopia in the United States between 1971-1972 and 1999-2004. Arch Ophthalmol 2009; 127: 1632–1639. 2. Shortsightedness on the rise across Europe, say researchers. The Guardian, 11th May 2015. 3. Dolgin E. The myopia boom. Nature 2015; 519: 276–278. 4. He M, Zeng J, Liu Y, Xu J, Pokharel GP & Ellwein LB. Refractive error and visual impairment in urban children in southern china. Invest Ophthalmol Vis Sci 2004; 45: 793–799. 5. Plainis S & Charman WN. Problems in comparisons of data for the prevalence of myopia and the frequency distribution of ametropia. Ophthalmic Physiol Opt 2015; 35: 394–404. 6. Mutti DO & Bullimore MA. Myopia: an epidemic of possibilities? Optom Vis Sci 1999; 76: 257–258. 7. Williams KM, Verhoeven VJ, Cumberland P et al. Prevalence of refractive error in Europe: the European Eye Epidemiology (E(3)) Consortium. Eur J Epidemiol 2015; 30: 305– 315. 8. Iribarren R, Cerrella MR, Armesto A, Iribarren G & Fornaciari A. Age of lens use onset in a myopic sample of officeworkers. Curr Eye Res 2004; 28: 175–180. 9. Wensor M, McCarty CA & Taylor HR. Prevalence and risk factors of myopia in Victoria, Australia. Arch Ophthalmol 1999; 117: 658–663. 10. Jones LA, Sinnott LT, Mutti DO, Mitchell GL, Moeschberger ML & Zadnik K. Parental history of myopia, sports and outdoor activities, and future myopia. Invest Ophthalmol Vis Sci 2007; 48: 3524–3532. 11. Ngo CS, Pan CW, Finkelstein EA et al. A cluster randomised controlled trial evaluating an incentive-based outdoor physical activity programme to increase outdoor time and prevent myopia in children. Ophthalmic Physiol Opt 2014; 34: 362–368. 12. Bullimore MA. Myopia control: the time is now. Ophthalmic Physiol Opt 2014; 34: 263–266.
© 2015 The Authors Ophthalmic & Physiological Optics © 2015 The College of Optometrists Ophthalmic & Physiological Optics 35 (2015) 349–351
M A Bullimore
Editorial
Mark A. Bullimore is an independent regulatory consultant and development professional based in Boulder, Colorado. He received his Optometry degree and PhD in Vision Science from Aston University in Birmingham, England. He was a Professor at The Ohio State University College of Optometry for 15 years and taught a number of courses, including geometric optics and ophthalmic optics. Previously, he spent 8 years at the University of California at Berkeley and is currently Adjunct Professor at the University of Houston College of Optometry. His research interests include myopia, low vision, presbyopia, and refractive surgery. He received grants from the National Institutes of Health to study adult myopia progression. He is Associate Editor of Ophthalmic and Physiological Optics and the former Editor of Optometry and Vision Science. He is former President and Development Director of the American Optometric Foundation, a philanthropic organization devoted to the advancement of optometric education and research. He served a four-year term on the U.S. Food and Drug Administration’s Ophthalmic Devices Panel and is a consultant for a number of ophthalmic, surgical, and pharmaceutical companies.
© 2015 The Authors Ophthalmic & Physiological Optics © 2015 The College of Optometrists Ophthalmic & Physiological Optics 35 (2015) 349–351
351
EDITORIAL
Myopia: an epidemic of possibilities? Figure 2 shows the prevalence of myopia for adults between 25 and 54 years. There is a higher frequency in the younger participants, consistent with an underlying increase in prevalence. In contrast, prevalence in the US sample of Vitale et al.,1 shown for comparison, varies little with age. Note that the prevalence of myopia approaches 50% in the youngest participants of both samples, although the European data are based on a stricter criterion for myopia—at least –0.75 D compared with any myopia. Finally, I’d like to highlight the most puzzling aspect of the prevalence data reported by Vitale et al.1 The underlying data are from participants selected ‘based on a multistage probability sample design using oversampling within selected age and race/ethnicity subgroups to estimate prevalence.’ In other words, meticulous care was taken in the selection of subjects so that the two samples, acquired thirty years apart, may be compared. Figure 3 shows the data for white participants with two data points highlighted. Given the passage of 30 years, the 18–24 year old participants from 1971 to 1972 should be comparable to the 45–54 year old participants in the 1999–2004 survey. The prevalence of myopia is 16.5% higher in the latter group (46.2% vs 29.7%), an increase that I have difficulty reconciling. One explanation is that one-third of all cases of myopia develop after the age of 24 years, but this is inconsistent with clinical experience and the limited research in the area.8 50
Prevalence of myopia (%)
The increasing prevalence of myopia1 has attracted recent attention in the popular press.2,3 It represents a significant public health issue, particularly in the case of high myopia which is a major cause of visual impairment in some Asian countries.4 Just as a picture is worth a thousand words, a paper showing a dramatic increase in a disease can launch hundreds of research grant submissions. Those of us working in the myopia field love to cite these papers in our applications for funding. In this issue of OPO, Plainis and Charman5 present a careful critique of the factors influencing the comparison and interpretation of myopia prevalence data, including the methods used to measure refractive error, the threshold chosen to define myopia and the influence of changes in refraction with age.6 Setting aside the clear and dramatic increase in the prevalence of myopia in Southeast Asia, I’d like to focus on some data from the West to further demonstrate the challenges faced in interpreting prevalence data. Vitale et al. reported a dramatic increase in the prevalence of myopia in the US population from 25.0% in 1971– 1972 to 41.6% in 1999–2004.1 They analyzed data from the ongoing National Health and Nutrition Examination Survey (NHANES), a nationally representative survey. Participants are interviewed in their homes and subsequently undergo a comprehensive examination in a mobile center. Vitale and colleagues’ data for white participants are replotted in Figure 1. These data show, at first glance, a compelling increase in prevalence in the 30 years between samples, but we must remember that each line shows an age dependence that represents a combination of factors including a possible underlying increase in prevalence over time and the wellestablished increased prevalence with age. Compare the 18– 24 and 25–34 year age groups in the 1999–2004 sample. The prevalence is almost 8% higher among the older of these two groups. If the underlying prevalence were increasing, wouldn’t we expect a higher prevalence among younger participants? A higher prevalence of myopia among younger subjects associated with an underlying increase has been observed in other large-scale studies. For example, Williams et al. estimated the prevalence of myopia in European adults using data collected between 1990 and 2013 for 61 946 individuals from fifteen population-based cohort and cross-sectional studies.7 These data from the European Eye Epidemiology (E3) Consortium were combined in a random effects meta-analysis stratified by 5-year age intervals.
40
30
20 1999–2004
10
1971–1972
0 12–17
18–24
25–34
35–44
45–54
Age (years) Figure 1. Prevalence of myopia among white participants from the National Health and Nutrition Examination Survey data from 1971– 1972 and 1999–2004. Redrawn from Vitale et al.1
© 2015 The Authors Ophthalmic & Physiological Optics © 2015 The College of Optometrists Ophthalmic & Physiological Optics 35 (2015) 349–351
349
Editorial
M A Bullimore
Prevalence of myopia (%)
50
a steady flow of opportunities for clinicians and researchers alike. I’ll leave you with the observation that in Australia the prevalence of myopia is relatively low and appears stable.9 The Australian population, like those discussed above, is of predominantly European ancestry, thus there is hope that modifiable risk factors, such as time spent outdoors,10,11 may be identified leading to strategies to reverse the apparent epidemic in most parts of the world.12
40
30 US (NHANES)
20
Mark A. Bullimore University of Houston College of Optometry, Houston, TX USA E-mail address: [email protected]
Europe (E3) 10
0
25–29
30–34
35–39
40–44
45–49
50–54
Age (years) Figure 2. Prevalence of myopia in European adults in the European Eye Epidemiology (E3) Consortium. Redrawn from Williams et al.7 Data from the 1999–2004 National Health and Nutrition Examination Survey data are shown for comaprison.1
Prevalence of myopia (%)
50
40
30
20 1999–2004
10
0
1971–1972
12–17
18–24
25–34
35–44
45–54
Age (years) Figure 3. Prevalence of myopia among white participants from the National Health and Nutrition Examination Survey data from 1971– 1972 and 1999–2004. Redrawn from Vitale et al.1
In summary, we must continue to view data on the prevalence of myopia with a critical eye. Even the most carefully designed and conducted studies can result in more questions than answers. In spite of the qualifications iterated eloquently by Plainis and Charman5 the prevalence of myopia is likely increasing, so we can thus look forward to
350
References 1. Vitale S, Sperduto RD & Ferris FL 3rd. Increased prevalence of myopia in the United States between 1971-1972 and 1999-2004. Arch Ophthalmol 2009; 127: 1632–1639. 2. Shortsightedness on the rise across Europe, say researchers. The Guardian, 11th May 2015. 3. Dolgin E. The myopia boom. Nature 2015; 519: 276–278. 4. He M, Zeng J, Liu Y, Xu J, Pokharel GP & Ellwein LB. Refractive error and visual impairment in urban children in southern china. Invest Ophthalmol Vis Sci 2004; 45: 793–799. 5. Plainis S & Charman WN. Problems in comparisons of data for the prevalence of myopia and the frequency distribution of ametropia. Ophthalmic Physiol Opt 2015; 35: 394–404. 6. Mutti DO & Bullimore MA. Myopia: an epidemic of possibilities? Optom Vis Sci 1999; 76: 257–258. 7. Williams KM, Verhoeven VJ, Cumberland P et al. Prevalence of refractive error in Europe: the European Eye Epidemiology (E(3)) Consortium. Eur J Epidemiol 2015; 30: 305– 315. 8. Iribarren R, Cerrella MR, Armesto A, Iribarren G & Fornaciari A. Age of lens use onset in a myopic sample of officeworkers. Curr Eye Res 2004; 28: 175–180. 9. Wensor M, McCarty CA & Taylor HR. Prevalence and risk factors of myopia in Victoria, Australia. Arch Ophthalmol 1999; 117: 658–663. 10. Jones LA, Sinnott LT, Mutti DO, Mitchell GL, Moeschberger ML & Zadnik K. Parental history of myopia, sports and outdoor activities, and future myopia. Invest Ophthalmol Vis Sci 2007; 48: 3524–3532. 11. Ngo CS, Pan CW, Finkelstein EA et al. A cluster randomised controlled trial evaluating an incentive-based outdoor physical activity programme to increase outdoor time and prevent myopia in children. Ophthalmic Physiol Opt 2014; 34: 362–368. 12. Bullimore MA. Myopia control: the time is now. Ophthalmic Physiol Opt 2014; 34: 263–266.
© 2015 The Authors Ophthalmic & Physiological Optics © 2015 The College of Optometrists Ophthalmic & Physiological Optics 35 (2015) 349–351
M A Bullimore
Editorial
Mark A. Bullimore is an independent regulatory consultant and development professional based in Boulder, Colorado. He received his Optometry degree and PhD in Vision Science from Aston University in Birmingham, England. He was a Professor at The Ohio State University College of Optometry for 15 years and taught a number of courses, including geometric optics and ophthalmic optics. Previously, he spent 8 years at the University of California at Berkeley and is currently Adjunct Professor at the University of Houston College of Optometry. His research interests include myopia, low vision, presbyopia, and refractive surgery. He received grants from the National Institutes of Health to study adult myopia progression. He is Associate Editor of Ophthalmic and Physiological Optics and the former Editor of Optometry and Vision Science. He is former President and Development Director of the American Optometric Foundation, a philanthropic organization devoted to the advancement of optometric education and research. He served a four-year term on the U.S. Food and Drug Administration’s Ophthalmic Devices Panel and is a consultant for a number of ophthalmic, surgical, and pharmaceutical companies.
© 2015 The Authors Ophthalmic & Physiological Optics © 2015 The College of Optometrists Ophthalmic & Physiological Optics 35 (2015) 349–351
351
