Elsevier

The Lancet

Volume 379, Issue 9827, 5–11 May 2012, Pages 1739-1748
The Lancet

Series
Myopia

https://doi.org/10.1016/S0140-6736(12)60272-4Get rights and content

Summary

Myopia has emerged as a major health issue in east Asia, because of its increasingly high prevalence in the past few decades (now 80–90% in school-leavers), and because of the sight-threatening pathologies associated with high myopia, which now affects 10–20% of those completing secondary schooling in this part of the world. Similar, but less marked, changes are occurring in other parts of the world. The higher prevalence of myopia in east Asian cities seems to be associated with increasing educational pressures, combined with life-style changes, which have reduced the time children spend outside. There are no reported major genes for school myopia, although there are several genes associated with high myopia. Any genetic contribution to ethnic differences may be small. However, to what extent many genes of small effect and gene-environment interactions contribute to variations in school myopia within populations remains to be established. There are promising optical and pharmacological interventions for preventing the development of myopia or slowing its progression, which require further validation, and promising vision-sparing treatments for pathological myopia.

Introduction

Myopia (short-sightedness or near-sightedness) is often regarded as a benign disorder, because vision can be corrected with glasses, contact lenses, and refractive surgery. Nevertheless, myopia has emerged as a major public health concern for three reasons: first, in developed countries in east and southeast Asia, such as Singapore, China, Taiwan, Hong Kong, Japan, and Korea, the prevalence of myopia has rapidly increased in the past 50–60 years.1, 2 In urban areas in these countries, 80–90% of children completing high school are now myopic, whereas 10–20% can have high myopia.3 These changes are not restricted to urbanised east Asia, since the prevalence of myopia is also increasing in North America,4 albeit more slowly, and probably in Europe as well. Second, the WHO recognises that myopia, if not fully corrected (uncorrected or under-corrected refractive error) is a major cause of visual impairment.5 Finally, people with high myopia are at a substantially increased risk of potentially blinding myopic pathologies, which are not prevented by optical correction.6

These factors call for adequate diagnosis and correction of myopic refractive errors, effective treatment of myopic pathologies, and, above all, prevention of myopia. Fortunately, our understanding of the cause of myopia has substantially progressed, leading to promising approaches to prevention, and so has our understanding of pathological myopia and its treatment.

Section snippets

Biological basis and definition

Refractive status is a complex variable, determined by the balance of the optical power of the cornea and the lens, and the axial length of the eye (with its component parts anterior chamber depth, lens thickness, and vitreal chamber depth). Myopia usually results from an eye that has become too long, particularly through elongation of the vitreal chamber.

Most children are born hyperopic, with a normal distribution of refractive errors.7 During the first year or two after birth, the

Epidemiology of myopia

Striking evidence exists for rapid increases in the prevalence of myopia, which has been considerably reviewed.1, 2 Rapid change was first noted in Inuits in North America as the populations moved into settlements,13 but it has been best documented in Singapore14, 15, 16, 17 and China (Taiwan3, 18 and Guangzhou19, 20) where the prevalence of myopia in different population-based birth cohorts can be compared. The data from Taiwan18 show that the prevalence of myopia has reached a plateau at a

Causes of myopia

50 years ago, myopia was believed to be genetic, with only minor environmental influences.25 However, results from experimental studies, including in primates, support the evidence of environmental factors from human epidemiology. These studies show that changes in visual experience by fitting of diffusers or both positive and negative lenses over the eyes can generate signals that promote eye growth, leading to myopia, as well as signals that slow eye growth.26

These models are relevant to

Environmental risk factors for myopia

The importance of environmental risk factors is strongly supported by experimentation with animals, and by the rapid changes in the prevalence of myopia. Associations of myopia with years of schooling and school results have been consistently reported.1 The very high prevalence of myopia in boys attending Orthodox schools in Israel compared with that seen in girls attending Orthodox schools in Israel and in all students attending Israeli secular schools is particularly striking.30 The rise in

Genetic risk factors for myopia

One key indicator of a genetic basis is familial clustering. In the case of myopia, sibling risk ratios are generally high, and even higher for high myopia.47 However, families share environments as well as genes, and sibling similarities in postulated myopigenic environmental factors are often higher than the sibling risk for myopia itself.48

Heritability values for myopia in twin studies have generally been high.49 Although apparently less ambiguous, twin heritability analysis depends on the

Ocular morbidity of myopia

Myopia is associated with other ocular disorders such as cataract63 and glaucoma,64 whereas it is negatively associated with age-related macular degeneration,65 but the causal connections are unknown. However, the major risk associated with myopia is the association between high myopia and ocular pathologies.

Pathological myopia associated with high myopia is particularly important because, in addition to the changes in overall myopia, in the urban centres of east Asia, the prevalence of high

Pathological myopia

Pathological myopia was originally described as high myopia accompanied by characteristic degenerative changes in the sclera, choroid, and retinal pigment epithelium, with compromised visual function.66 Not all highly myopic eyes develop pathological myopia, and attempts have been made to define highly myopic eyes at high risk as those with an axial length of more than 3 (SD) from the mean for emmetropic eyes. Although issues associated with differing definitions of high myopia and signs of

Interventions to control myopia

Interventions to control myopia are of two kinds. Those aimed at prevention of myopia need to be minimally invasive, since they would be applied to children who do not require glasses. Once myopia is developed, progression can continue throughout childhood and, particularly in high myopia, throughout adult life. In this situation, more invasive interventions are possible. Myopic pathologies increase with greater myopic refractive error, and even partial prevention of progression can provide

Conclusions and future priorities

Myopia is an increasingly widespread condition around the world, but particularly in east Asia. Effective reduction of visual impairment is available with optical correction by spectacles, contact lenses, and refractive surgery.

From a clinical perspective, the major priorities for future research lie with the prevention of incident myopia and myopic progression leading to the development of high myopia, and several evidence-based approaches are currently under trial. Health behaviour programmes

Search strategy and selection criteria

We searched the Medline and Online Mendelian Inheritance in Man (OMIM) databases using the search terms “myopia”, “high myopia”, and “pathological myopia”, alone or in combination with “prevalence”, “epidemiology”, “genetics”, and “prevention”. We made a separate search for “stationary night blindness”. Names of authors and reference lists from relevant article lists were used as the basis for further searches. Where possible, review articles or meta-analyses that contain comprehensive

References (101)

  • MW Marcus et al.

    Myopia as a risk factor for open-angle glaucoma: a systematic review and meta-analysis

    Ophthalmology

    (2011)
  • HH Liu

    Prevalence and progression of myopic retinopathy in Chinese adults: the Beijing Eye Study

    Ophthalmology

    (2010)
  • J Vongphanit et al.

    Prevalence and progression of myopic retinopathy in an older population

    Ophthalmology

    (2002)
  • SY Cohen et al.

    Etiology of choroidal neovascularization in young patients

    Ophthalmology

    (1996)
  • M Moriyama et al.

    Topographic analyses of shape of eyes with pathologic myopia by high-resolution three-dimensional magnetic resonance imaging

    Ophthalmology

    (2011)
  • K Ohno-Matsui et al.

    Long-term development of significant visual field defects in highly myopic eyes

    Am J Ophthalmol

    (2011)
  • NA McBrien et al.

    Role of the sclera in the development and pathological complications of myopia

    Prog Retin Eye Res

    (2003)
  • T Baba et al.

    Prevalence and characteristics of foveal retinal detachment without macular hole in high myopia

    Am J Ophthalmol

    (2003)
  • A Nishimura et al.

    Efficacy of primary silicone oil tamponade for the treatment of retinal detachment caused by macular hole in high myopia

    Am J Ophthalmol

    (2011)
  • K Suda et al.

    Axial length and outcomes of macular hole surgery assessed by spectral-domain optical coherence tomography

    Am J Ophthalmol

    (2011)
  • M Takano et al.

    Foveal retinoschisis and retinal detachment in severely myopic eyes with posterior staphyloma

    Am J Ophthalmol

    (1999)
  • N Shimada et al.

    Natural course of macular retinoschisis in highly myopic eyes without macular hole or retinal detachment

    Am J Ophthalmol

    (2006)
  • NS Anstice et al.

    Effect of dual-focus soft contact lens wear on axial myopia progression in children

    Ophthalmology

    (2011)
  • A Chia et al.

    Atropine for the Treatment of Childhood Myopia: Safety and Efficacy of 0·5%, 0·1%, and 0·01% Doses (Atropine for the Treatment of Myopia 2)

    Ophthalmology

    (2012)
  • CW Pan et al.

    Worldwide prevalence and risk factors for myopia

    Ophthalmic Physiol Opt

    (2012)
  • LL Lin et al.

    Prevalence of myopia in Taiwanese schoolchildren: 1983 to 2000

    Ann Acad Med Singapore

    (2004)
  • S Vitale et al.

    Increased prevalence of myopia in the United States between 1971–1972 and 1999–2004

    Arch Ophthalmol

    (2009)
  • S Resnikoff et al.

    Global magnitude of visual impairment caused by uncorrected refractive errors in 2004

    Bull World Health Organ

    (2008)
  • SM Saw et al.

    Myopia and associated pathological complications

    Ophthalmic Physiol Opt

    (2005)
  • DL Mayer et al.

    Cycloplegic refractions in healthy children aged 1 through 48 months

    Arch Ophthalmol

    (2001)
  • RA Gordon et al.

    Refractive development of the human eye

    Arch Ophthalmol

    (1985)
  • LA Jones et al.

    Comparison of ocular component growth curves among refractive error groups in children

    Invest Ophthalmol Vis Sci

    (2005)
  • PM Cumberland et al.

    Inferring myopia over the lifecourse from uncorrected distance visual acuity in childhood

    Br J Ophthalmol

    (2007)
  • B Benjamin et al.

    Emmetropia and its aberrations; a study in the correlation of the optical components of the eye

    Spec Rep Ser Med Res Counc (GB)

    (1957)
  • FA Young et al.

    The transmission of refractive errors within eskimo families

    Am J Optom Arch Am Acad Optom

    (1969)
  • CW Pan et al.

    Prevalence and risk factors for refractive errors in Indians: the Singapore Indian Eye Study (SINDI)

    Invest Ophthalmol Vis Sci

    (2011)
  • TY Wong et al.

    Prevalence and risk factors for refractive errors in adult Chinese in Singapore

    Invest Ophthalmol Vis Sci

    (2000)
  • HM Wu et al.

    Does education explain ethnic differences in myopia prevalence? A population-based study of young adult males in Singapore

    Optom Vis Sci

    (2001)
  • CY Cheng et al.

    Refractive errors in an elderly Chinese population in Taiwan: the Shihpai Eye Study

    Invest Ophthalmol Vis Sci

    (2003)
  • M He et al.

    Refractive error and biometry in older Chinese adults: the Liwan eye study

    Invest Ophthalmol Vis Sci

    (2009)
  • M He et al.

    Refractive error and visual impairment in urban children in southern china

    Invest Ophthalmol Vis Sci

    (2004)
  • R Wojciechowski

    Nature and nurture: the complex genetics of myopia and refractive error

    Clin Genet

    (2011)
  • NA Rosenberg et al.

    Genetic structure of human populations

    Science

    (2002)
  • KG Au Eong et al.

    Race, culture and Myopia in 110,236 young Singaporean males

    Singapore Med J

    (1993)
  • MT Tay et al.

    Myopia and educational attainment in 421,116 young Singaporean males

    Ann Acad Med Singapore

    (1992)
  • A Sorsby

    Refraction and its components in twins. Privy council, Medical research council, Special report series, n 303

    (1962)
  • DO Mutti et al.

    Has near work's star fallen?

    Optom Vis Sci

    (2009)
  • Saw S-M, Yang A, Chan Y-H, Tey F, Nah G. The increase in myopia prevalence in young male Singaporeans from 1996–1997 to...
  • R Zylbermann et al.

    The influence of study habits on myopia in Jewish teenagers

    J Pediatr Ophthalmol Strabismus

    (1993)
  • SM Saw et al.

    Nearwork in early-onset myopia

    Invest Ophthalmol Vis Sci

    (2002)
  • Cited by (0)

    View full text