Editing Myopia (section)

==Causes==
The underlying cause of myopia is believed to be a combination of genetic and environmental factors.<ref name=Fos2014/><ref>{{Cite journal |last1=Wang |first1=Yu-Meng |last2=Lu |first2=Shi-Yao |last3=Zhang |first3=Xiu-Juan |last4=Chen |first4=Li-Jia |last5=Pang |first5=Chi-Pui |last6=Yam |first6=Jason C. |date=2022-03-09 |title=Myopia Genetics and Heredity |journal=Children |volume=9 |issue=3 |pages=382 |doi=10.3390/children9030382 |issn=2227-9067 |pmc=8947159 |pmid=35327754 |doi-access=free }}</ref><ref>{{Cite journal |last1=Li |first1=Jiali |last2=Zhang |first2=Qingjiong |date=2017-12-31 |title=Insight into the molecular genetics of myopia |journal=Molecular Vision |volume=23 |pages=1048–1080 |issn=1090-0535 |pmc=5757860 |pmid=29386878}}</ref> Risk factors include doing work that involves focusing on close objects, greater time spent indoors, urbanization, and a family history of the condition.<ref name=Fos2014/><ref name=Pan2012/><ref>{{cite journal | vauthors = Huang HM, Chang DS, Wu PC | title = The Association between Near Work Activities and Myopia in Children-A Systematic Review and Meta-Analysis | journal = PLOS ONE | volume = 10 | issue = 10 | pages = e0140419 | date = 2015 | pmid = 26485393 | pmc = 4618477 | doi = 10.1371/journal.pone.0140419 | doi-access = free | bibcode = 2015PLoSO..1040419H }}</ref><ref name=":0">{{cite journal | vauthors = Shapira Y, Mimouni M, Machluf Y, Chaiter Y, Saab H, Mezer E | title = The Increasing Burden of Myopia in Israel among Young Adults over a Generation: Analysis of Predisposing Factors | journal = Ophthalmology | volume = 126 | issue = 12 | pages = 1617–1626 | date = December 2019 | pmid = 31474440 | doi = 10.1016/j.ophtha.2019.06.025 | s2cid = 198380872 }}</ref> It is also associated with a high [[socioeconomic class]] and higher level of education.<ref name=Fos2014/><ref name=":0" />

A 2012 review could not find strong evidence for any single cause, although many theories have been discredited.<ref name="Sivak2012">{{cite journal | vauthors = Sivak J | title = The cause(s) of myopia and the efforts that have been made to prevent it | journal = Clinical & Experimental Optometry | volume = 95 | issue = 6 | pages = 572–82 | date = November 2012 | pmid = 22845416 | doi = 10.1111/j.1444-0938.2012.00781.x | s2cid = 32003286 }}</ref> [[Twin studies]] indicate that at least some genetic factors are involved.<ref name=Val2019 /><ref>{{Cite journal |last1=Cai |first1=Xue-Bi |last2=Shen |first2=Shou-Ren |last3=Chen |first3=De-Fu |last4=Zhang |first4=Qingjiong |last5=Jin |first5=Zi-Bing |date=2019-11-01 |title=An overview of myopia genetics |journal=Experimental Eye Research |language=en |volume=188 |pages=107778 |doi=10.1016/j.exer.2019.107778 |pmid=31472110 |s2cid=201700595 |issn=0014-4835|doi-access=free }}</ref><ref>{{Cite journal |last1=Polderman |first1=Tinca J. C. |last2=Benyamin |first2=Beben |last3=de Leeuw |first3=Christiaan A. |last4=Sullivan |first4=Patrick F. |last5=van Bochoven |first5=Arjen |last6=Visscher |first6=Peter M. |last7=Posthuma |first7=Danielle |date=2015-07-01 |title=Meta-analysis of the heritability of human traits based on fifty years of twin studies |url=https://www.nature.com/articles/ng.3285 |journal=Nature Genetics |language=en |volume=47 |issue=7 |pages=702–709 |doi=10.1038/ng.3285 |pmid=25985137 |s2cid=205349969 |issn=1546-1718}}</ref> Myopia has been increasing rapidly throughout the developed world, suggesting environmental factors are involved.<ref name="Dolgin">{{cite journal | vauthors = Dolgin E | title = The myopia boom | journal = Nature | volume = 519 | issue = 7543 | pages = 276–8 | date = March 2015 | pmid = 25788077 | doi = 10.1038/519276a | bibcode = 2015Natur.519..276D | doi-access = free }}</ref>

The role of corrective lenses interfering with [[Emmetropia#Emmetropization|emmetropization]] has also been suggested.<ref name="Medina">{{cite journal | vauthors = Medina A | title = The cause of myopia development and progression: Theory, evidence, and treatment | journal = Survey of Ophthalmology | volume = 67| issue = 2| pages = 488–509| date = June 2021 | doi = 10.1016/j.survophthal.2021.06.005 | pmid = 34181975 | doi-access = free }}</ref><ref name=":7">{{Cite journal |last1=Biswas |first1=Sayantan |last2=El Kareh |first2=Antonio |last3=Qureshi |first3=Mariyem |last4=Lee |first4=Deborah Mei Xuan |last5=Sun |first5=Chen-Hsin |last6=Lam |first6=Janice S.H. |last7=Saw |first7=Seang-Mei |last8=Najjar |first8=Raymond P. |date=2024-01-31 |title=The influence of the environment and lifestyle on myopia |journal=Journal of Physiological Anthropology |volume=43 |issue=1 |pages=7 |doi=10.1186/s40101-024-00354-7 |doi-access=free |issn=1880-6805 |pmc=10829372 |pmid=38297353}}</ref>

===Genetics===
A risk for myopia may be inherited from one's parents.<ref>{{cite web |title=Myopia (Nearsightedness) |url=http://www.aoa.org/patients-and-public/eye-and-vision-problems/glossary-of-eye-and-vision-conditions/myopia |website=www.aoa.org |access-date=25 December 2019 |language=en}}</ref> [[Genetic linkage]] studies have identified 18 possible loci on 15 different [[chromosome]]s that are associated with myopia, but none of these loci is part of the candidate genes that cause myopia. Instead of a simple one-gene locus controlling the onset of myopia, a complex interaction of many mutated proteins acting in concert may be the cause. Instead of myopia being caused by a defect in a structural protein, defects in the control of these structural proteins might be the actual cause of myopia.<ref>{{cite journal | vauthors = Jacobi FK, Pusch CM | title = A decade in search of myopia genes | journal = Frontiers in Bioscience | volume = 15 | pages = 359–72 | date = January 2010 | issue = 1 | pmid = 20036825 | doi = 10.2741/3625 | doi-access = free }}</ref> A collaboration of all myopia studies worldwide identified 16 new loci for refractive error in individuals of European ancestry, of which 8 were shared with Asians. The new loci include candidate genes with functions in neurotransmission, ion transport, retinoic acid metabolism, extracellular matrix remodeling and eye development. The carriers of the high-risk genes have a tenfold increased risk of myopia.<ref>{{cite journal | vauthors = Verhoeven VJ, Hysi PG, Wojciechowski R, Fan Q, Guggenheim JA, Höhn R, MacGregor S, Hewitt AW, Nag A, Cheng CY, Yonova-Doing E, Zhou X, Ikram MK, Buitendijk GH, McMahon G, Kemp JP, Pourcain BS, Simpson CL, Mäkelä KM, Lehtimäki T, Kähönen M, Paterson AD, Hosseini SM, Wong HS, Xu L, Jonas JB, Pärssinen O, Wedenoja J, Yip SP, Ho DW, Pang CP, Chen LJ, Burdon KP, Craig JE, Klein BE, Klein R, Haller T, Metspalu A, Khor CC, Tai ES, Aung T, Vithana E, Tay WT, Barathi VA, Chen P, Li R, Liao J, Zheng Y, Ong RT, Döring A, Evans DM, Timpson NJ, Verkerk AJ, Meitinger T, Raitakari O, Hawthorne F, Spector TD, Karssen LC, Pirastu M, Murgia F, Ang W, Mishra A, Montgomery GW, Pennell CE, Cumberland PM, Cotlarciuc I, Mitchell P, Wang JJ, Schache M, Janmahasatian S, Janmahasathian S, Igo RP, Lass JH, Chew E, Iyengar SK, Gorgels TG, Rudan I, Hayward C, Wright AF, Polasek O, Vatavuk Z, Wilson JF, Fleck B, Zeller T, Mirshahi A, Müller C, Uitterlinden AG, Rivadeneira F, Vingerling JR, Hofman A, Oostra BA, Amin N, Bergen AA, Teo YY, Rahi JS, Vitart V, Williams C, Baird PN, Wong TY, Oexle K, Pfeiffer N, Mackey DA, Young TL, van Duijn CM, Saw SM, Bailey-Wilson JE, Stambolian D, Klaver CC, Hammond CJ | display-authors = 6 | title = Genome-wide meta-analyses of multiancestry cohorts identify multiple new susceptibility loci for refractive error and myopia | journal = Nature Genetics | volume = 45 | issue = 3 | pages = 314–8 | date = March 2013 | pmid = 23396134 | pmc = 3740568 | doi = 10.1038/ng.2554 }}</ref> Aberrant genetic recombination and gene splicing in the OPNLW1 and OPNMW1 genes that code for two retinal cone photopigment proteins can produce high myopia by interfering with refractive development of the eye.<ref>{{cite journal | vauthors = Neitz M, Neitz J | title = Intermixing the OPN1LW and OPN1MW Genes Disrupts the Exonic Splicing Code Causing an Array of Vision Disorders | journal = Genes | volume = 12 | issue = 8 | pages = 1180 | date = August 2021 | pmid = 34440353 | pmc = 8391646 | doi = 10.3390/genes12081180 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Li J, Gao B, Guan L, Xiao X, Zhang J, Li S, Jiang H, Jia X, Yang J, Guo X, Yin Y, Wang J, Zhang Q | display-authors = 6 | title = Unique Variants in OPN1LW Cause Both Syndromic and Nonsyndromic X-Linked High Myopia Mapped to MYP1 | journal = Investigative Ophthalmology & Visual Science | volume = 56 | issue = 6 | pages = 4150–4155 | date = June 2015 | pmid = 26114493 | doi = 10.1167/iovs.14-16356 }}</ref>

Human population studies suggest that contribution of genetic factors accounts for 60–90% of variance in refraction.<ref name="pmid17065484">{{cite journal | vauthors = Dirani M, Chamberlain M, Shekar SN, Islam AF, Garoufalis P, Chen CY, Guymer RH, Baird PN | display-authors = 6 | title = Heritability of refractive error and ocular biometrics: the Genes in Myopia (GEM) twin study | journal = Investigative Ophthalmology & Visual Science | volume = 47 | issue = 11 | pages = 4756–61 | date = November 2006 | pmid = 17065484 | doi = 10.1167/iovs.06-0270 | doi-access = free }}</ref><ref name="pmid18757506">{{cite journal | vauthors = Lopes MC, Andrew T, Carbonaro F, Spector TD, Hammond CJ | title = Estimating heritability and shared environmental effects for refractive error in twin and family studies | journal = Investigative Ophthalmology & Visual Science | volume = 50 | issue = 1 | pages = 126–31 | date = January 2009 | pmid = 18757506 | doi = 10.1167/iovs.08-2385 | doi-access = free }}</ref><ref name="pmid17724179">{{cite journal | vauthors = Peet JA, Cotch MF, Wojciechowski R, Bailey-Wilson JE, Stambolian D | title = Heritability and familial aggregation of refractive error in the Old Order Amish | journal = Investigative Ophthalmology & Visual Science | volume = 48 | issue = 9 | pages = 4002–6 | date = September 2007 | pmid = 17724179 | pmc = 1995233 | doi = 10.1167/iovs.06-1388 }}</ref><ref name="pmid26313004">{{cite journal | vauthors = Tkatchenko AV, Tkatchenko TV, Guggenheim JA, Verhoeven VJ, Hysi PG, Wojciechowski R, Singh PK, Kumar A, Thinakaran G, Williams C | display-authors = 6 | title = APLP2 Regulates Refractive Error and Myopia Development in Mice and Humans | journal = PLOS Genetics | volume = 11 | issue = 8 | pages = e1005432 | date = August 2015 | pmid = 26313004 | pmc = 4551475 | doi = 10.1371/journal.pgen.1005432 | doi-access = free }}</ref> However, the currently identified variants account for only a small fraction of myopia cases, suggesting the existence of a large number of yet unidentified low-frequency or small-effect variants, which underlie the majority of myopia cases.<ref name="pmid24385918">{{cite journal | vauthors = Gusev A, Bhatia G, Zaitlen N, Vilhjalmsson BJ, Diogo D, Stahl EA, Gregersen PK, Worthington J, Klareskog L, Raychaudhuri S, Plenge RM, Pasaniuc B, Price AL | display-authors = 6 | title = Quantifying missing heritability at known GWAS loci | journal = PLOS Genetics | volume = 9 | issue = 12 | pages = e1003993 | year = 2013 | pmid = 24385918 | pmc = 3873246 | doi = 10.1371/journal.pgen.1003993 | doi-access = free }}</ref>

===Environmental factors===
Environmental factors that increase the risk of myopia include insufficient light exposure, low physical activity, near work, and increased years of education.<ref name=Val2019/><ref name=":7" />

One hypothesis is that a lack of normal visual stimuli causes improper development of the eyeball. Under this hypothesis, "normal" refers to the environmental stimuli that the eyeball evolved to.<ref name="Lieberman">Lieberman, Daniel E. (2013) ''The Story of the Human Body: Evolution, Health, and Disease''. New York: Pantheon Books.{{page needed|date=January 2022}}</ref> Modern humans who spend most of their time indoors, in dimly or fluorescently lit buildings may be at risk of development of myopia.<ref name="Lieberman"/>

People, and children especially, who spend more time doing [[physical exercise]] and [[Outdoor recreation|outdoor play]], have lower rates of myopia,<ref name="BBC">{{cite news|url=https://www.bbc.co.uk/news/health-15427954|title=Lack of outdoor play linked to short-sighted children| vauthors = Sherwin J |date=25 October 2011|work=BBC News|access-date=25 October 2011|archive-url=https://web.archive.org/web/20111025171847/http://www.bbc.co.uk/news/health-15427954|archive-date=25 October 2011|url-status=live}}</ref><ref name="Lieberman"/><ref name="Dirani">{{cite journal | vauthors = Dirani M, Tong L, Gazzard G, Zhang X, Chia A, Young TL, Rose KA, Mitchell P, Saw SM | display-authors = 6 | title = Outdoor activity and myopia in Singapore teenage children | journal = The British Journal of Ophthalmology | volume = 93 | issue = 8 | pages = 997–1000 | date = August 2009 | pmid = 19211608 | doi = 10.1136/bjo.2008.150979 | s2cid = 30301026 }}</ref><ref name="Rose">{{cite journal | vauthors = Rose KA, Morgan IG, Ip J, Kifley A, Huynh S, Smith W, Mitchell P | title = Outdoor activity reduces the prevalence of myopia in children | journal = Ophthalmology | volume = 115 | issue = 8 | pages = 1279–85 | date = August 2008 | pmid = 18294691 | doi = 10.1016/j.ophtha.2007.12.019 }}</ref><ref name="Dolgin" /> suggesting the increased magnitude and complexity of the visual stimuli encountered during these types of activities decrease myopic progression. There is preliminary evidence that the protective effect of outdoor activities on the development of myopia is due, at least in part, to the effect of long hours of exposure to [[daylight]] on the production and the release of retinal [[dopamine]].<ref name="Dolgin"/><ref>{{cite journal | vauthors = Cui D, Trier K, Munk Ribel-Madsen S | title = Effect of day length on eye growth, myopia progression, and change of corneal power in myopic children | journal = Ophthalmology | volume = 120 | issue = 5 | pages = 1074–9 | date = May 2013 | pmid = 23380471 | doi = 10.1016/j.ophtha.2012.10.022 }}</ref><ref name="pmid23434455">{{cite journal | vauthors = Feldkaemper M, Schaeffel F | title = An updated view on the role of dopamine in myopia | journal = Experimental Eye Research | volume = 114 | pages = 106–19 | date = September 2013 | pmid = 23434455 | doi = 10.1016/j.exer.2013.02.007 | s2cid = 35493712 | type = review }}</ref><ref name="pmid23298452">{{cite journal | vauthors = Nickla DL | title = Ocular diurnal rhythms and eye growth regulation: where we are 50 years after Lauber | journal = Experimental Eye Research | volume = 114 | pages = 25–34 | date = September 2013 | pmid = 23298452 | pmc = 3742730 | doi = 10.1016/j.exer.2012.12.013 | type = Review }}</ref>

Myopia can be induced with minus spherical lenses,<ref>{{cite journal |last1=Nickla |first1=Debora L. |last2=Jordan |first2=Kelsey |last3=Yang |first3=Jane |last4=Totonelly |first4=Kristen |title=Brief hyperopic defocus or form deprivation have varying effects on eye growth and ocular rhythms depending on the time-of-day of exposure |journal=Experimental Eye Research |date=1 August 2017 |volume=161 |pages=132–142 |doi=10.1016/j.exer.2017.06.003 |pmid=28596085 |pmc=5557081 }}</ref> and overminus in prescription lenses can induce myopia progression.<ref>{{Cite web|url=https://www.reviewofoptometry.com/article/overminus-lenses-associated-with-myopia-progression|title = Overminus Lenses Associated with Myopia Progression}}</ref><ref name="overminus">https://www.optometrystudents.com/pearl/over-minus-you-probably-do-itstop-it/ {{Webarchive|url=https://web.archive.org/web/20221202062113/https://www.optometrystudents.com/pearl/over-minus-you-probably-do-itstop-it/ |date=2 December 2022 }}{{medrs|date=January 2022}}{{full citation needed|date=January 2022}}</ref> Overminus during refraction can be avoided through various techniques and tests, such as fogging, plus to blur, and the [[duochrome test]].<ref name="overminus" />

The near work hypothesis, also referred to as the "use-abuse theory", states that spending time involved in near work strains the intraocular and extraocular muscles. Some studies support the hypothesis, while other studies do not.<ref name=Pan2012/> While an association is present, it is not clearly causal.<ref name=Pan2012/>

Myopia is also more common in children with [[diabetes]], [[childhood arthritis]], [[uveitis]], and [[systemic lupus erythematosus]].<ref name=Val2019/>

===Other factors===
Research indicates a relationship between [[Body mass index|body mass index (BMI)]] and myopia, with both low and high BMI associated with an increased risk of developing myopia. A nationwide study of 1.3 million Israeli adolescents found that individuals with [[underweight]] status had higher chances of mild-to-moderate and high myopia compared to those with low-normal BMI.<ref>{{Cite journal |last1=Peled |first1=Alon |last2=Nitzan |first2=Itay |last3=Megreli |first3=Jacob |last4=Derazne |first4=Estela |last5=Tzur |first5=Dorit |last6=Pinhas-Hamiel |first6=Orit |last7=Afek |first7=Arnon |last8=Twig |first8=Gilad |date=August 2022 |title=Myopia and BMI: a nationwide study of 1.3 million adolescents |url=https://pubmed.ncbi.nlm.nih.gov/35894082/ |journal=Obesity |volume=30 |issue=8 |pages=1691–1698 |doi=10.1002/oby.23482 |issn=1930-739X |pmid=35894082}}</ref>

Similarly, a study involving Korean young adult men reported that those who were of average or shorter height and lean had a higher prevalence of high myopia.<ref>{{Cite journal |last1=Qu |first1=Yaohui |last2=Huang |first2=Huamin |last3=Zhang |first3=Hongxing |date=2023-12-05 |title=Association between body mass index and myopia in the United States population in the National Health and Nutrition Examination Surveys 1999 to 2008: a cross-sectional study |journal=European Journal of Medical Research |volume=28 |issue=1 |pages=561 |doi=10.1186/s40001-023-01542-4 |doi-access=free |issn=2047-783X |pmc=10696841 |pmid=38049883}}</ref><ref>{{Cite journal |title=An epidemiological study of the risk factors associated with myopia in young adult men in Korea |date=2018 |pmc=5764954 |journal=Scientific Reports |volume=8 |issue=1 |page=511 |doi=10.1038/s41598-017-18926-2 |pmid=29323203 |bibcode=2018NatSR...8..511L | vauthors = Lee DC, Lee SY, Kim YC }}</ref>