Editing Myopia

{{Short description|Inability to focus in distant objects}}
{{Other uses}}
{{cs1 config|name-list-style=vanc}}
{{Use dmy dates|date=February 2020}}
{{Infobox medical condition (new)
| name = Myopia
| image = Myopia.gif
| caption = Diagram showing changes in the eye with myopia
| field = [[Ophthalmology]], [[optometry]]
| synonyms = near-sightedness, short-sightedness
| symptoms = Distant objects appear [[blurred vision|blurry]], [[headache]]s, [[eye strain]]<ref name=NIH2010/>
| complications = [[Retinal detachment]], [[cataract]]s, [[glaucoma]]<ref name="Fos2014">{{cite journal | vauthors = Foster PJ, Jiang Y | title = Epidemiology of myopia | journal = Eye | volume = 28 | issue = 2 | pages = 202–8 | date = February 2014 | pmid = 24406412 | pmc = 3930282 | doi = 10.1038/eye.2013.280 }}</ref>
| onset = 
| duration = Typically permanent once it develops
| causes = Combination of genetic and environmental factors<ref name=Fos2014/>
| risks = Near work, greater time spent indoors, family history<ref name=Fos2014/><ref name=Pan2012/>
| diagnosis = [[Eye examination]]<ref name=NIH2010/>
| differential = 
| prevention = Unknown
| treatment = [[Eyeglass]]es, [[contact lenses]], [[surgery]]<ref name=NIH2010/>
| medication = Low-dose Atropine Eye drops<ref>{{cite web |title=Myopia Control Clinic |url=https://www.uab.edu/optometry/home/uab-eye-care/myopia-control-clinic |website=University of Alabama at Birmingham |access-date=2025-04-28}}</ref>
| prognosis = Generally stable after it progresses in early adulthood. <ref>{{cite journal |last=Jackson |first=Timothy L. |last2=Vote |first2=Brendan |last3=Knight |first3=Bruce C. |last4=El-Amir |first4=Ahmed |last5=Stanford |first5=Miles R. |title=Safety Testing of Infracyanine Green Using Retinal Pigment Epithelium and Glial Cell Cultures |journal=Investigative Ophthalmology & Visual Science |volume=45 |issue=10 |pages=3588–3593 |year=2004 |doi=10.1167/iovs.04-0304}}</ref>
| frequency = Approximately 30% of people around the world<ref>{{cite journal |last=Sankaridurg |first=Padmaja |first2=Nina |last2=Tahhan |first3=Himal |last3=Kandel |first4=Thomas |last4=Naduvilath |first5=Haidong |last5=Zou |first6=Kevin D. |last6=Frick |first7=Srinivas |last7=Marmamula |first8=David S. |last8=Friedman |first9=Ecosse |last9=Lamoureux |first10=Jill |last10=Keeffe |first11=Jeffrey J. |last11=Walline |first12=Timothy R. |last12=Fricke |first13=Vilas |last13=Kovai |first14=Serge |last14=Resnikoff |title=IMI Impact of Myopia |journal=Investigative Ophthalmology & Visual Science |volume=62 |issue=5 |pages=2 |year=2021 |url=https://iovs.arvojournals.org/article.aspx?articleid=2772540 |doi=10.1167/iovs.62.5.2 |access-date=2025-04-28}}</ref>
| deaths = Not deadly
}}
<!-- Definition and symptoms -->

'''Myopia''', also known as '''near-sightedness''' and '''short-sightedness''',<ref name=":6">{{Cite book |last=Bikas |first=Bhattacharyya |title=Textbook of Visual Science and Clinical Optometry |publisher=Jaypee Brothers Medical Publisher |year=2009 |isbn=9788184485998 |edition=First |location=New Delhi, India |publication-date=2009 |pages=143 |language=English}}</ref> is an eye condition<ref>https://www.carehospitals.com/diseases-conditions/myopia</ref><ref>https://www.specsavers.co.uk/eye-health/myopia</ref> where light from distant objects focuses in front of, instead of on, the [[retina]].<ref name="NIH2010" /><ref name="Fos2014" /><ref name=":5">{{Cite web |date=2022-09-22 |title=Nearsightedness: What Is Myopia? |url=https://www.aao.org/eye-health/diseases/myopia-nearsightedness |access-date=2023-10-03 |website=American Academy of Ophthalmology |language=en}}</ref> As a result, distant objects appear [[blurred vision|blurry]], while close objects appear normal.<ref name="NIH2010" /> Other symptoms may include [[headache]]s and [[eye strain]].<ref name="NIH2010">{{cite web|title=Facts About Refractive Errors|url=https://nei.nih.gov/health/errors/errors|website=NEI|access-date=30 July 2016|date=October 2010|url-status=live|archive-url=https://web.archive.org/web/20160728000730/https://nei.nih.gov/health/errors/errors|archive-date=28 July 2016}}</ref><ref>{{Cite web |last=Whitney |first=Seltman |title=Eye Health and Nearsightedness in Children and Adults |url=https://www.webmd.com/eye-health/nearsightedness-myopia |access-date=2023-10-03 |website=WebMD |language=en}}</ref> Severe myopia is associated with an increased risk of [[macular degeneration]], [[retinal detachment]], [[cataract]]s, and [[glaucoma]].<ref name="Fos2014" /><ref>{{Cite journal |last1=Haarman |first1=Annechien E. G. |last2=Enthoven |first2=Clair A. |last3=Tideman |first3=J. Willem L. |last4=Tedja |first4=Milly S. |last5=Verhoeven |first5=Virginie J. M. |last6=Klaver |first6=Caroline C. W. |date=2020-04-29 |title=The Complications of Myopia: A Review and Meta-Analysis |journal=Investigative Ophthalmology & Visual Science |volume=61 |issue=4 |pages=49 |doi=10.1167/iovs.61.4.49 |issn=0146-0404 |pmc=7401976 |pmid=32347918}}</ref>

<!-- Cause and diagnosis -->
Myopia results from the length of the eyeball growing too long or less commonly the [[Lens (anatomy)|lens]] being too strong.<ref name="NIH2010" /><ref>{{cite book| vauthors = Ledford A, Nemeth SC, Ledford JK |title=Ocular anatomy and physiology |date=2008 |publisher=SLACK |location=Thorofare, NJ|isbn=9781556427923 |page=158|edition=2nd|url=https://books.google.com/books?id=Cphm_fxwvl8C&pg=PA158|url-status=live|archive-url=https://web.archive.org/web/20170908155641/https://books.google.com/books?id=Cphm_fxwvl8C&pg=PA158|archive-date=8 September 2017}}</ref> It is a type of [[refractive error]].<ref name=NIH2010/> Diagnosis is by the use of [[Cycloplegic refraction|cycloplegics]] during eye examination.<ref name=":4">{{Cite book |last=Ajay Kumar |first=Bhootra |title=Clinical Refraction Guide |publisher=Jaypee Brothers Medical Publishers (P) LTD |year=2014 |isbn=978-93-5152-063-4 |edition=First |location=New Delhi, India |pages=63 |language=English}}</ref><!-- Prevention and treatment -->

Tentative evidence indicates that the risk of myopia can be decreased by having young children spend more time outside.<ref name=Ram2015>{{cite journal | vauthors = Ramamurthy D, Lin Chua SY, Saw SM | title = A review of environmental risk factors for myopia during early life, childhood and adolescence | journal = Clinical & Experimental Optometry | volume = 98 | issue = 6 | pages = 497–506 | date = November 2015 | pmid = 26497977 | doi = 10.1111/cxo.12346 | type = Review | doi-access = free }}</ref><ref>{{cite journal | vauthors = Xiong S, Sankaridurg P, Naduvilath T, Zang J, Zou H, Zhu J, Lv M, He X, Xu X | display-authors = 6 | title = Time spent in outdoor activities in relation to myopia prevention and control: a meta-analysis and systematic review | journal = Acta Ophthalmologica | volume = 95 | issue = 6 | pages = 551–566 | date = September 2017 | pmid = 28251836 | pmc = 5599950 | doi = 10.1111/aos.13403 }}</ref> This decrease in risk may be related to [[Daylighting (architecture)|natural light]] exposure.<ref>{{cite journal | vauthors = Hobday R | title = Myopia and daylight in schools: a neglected aspect of public health? | journal = Perspectives in Public Health | volume = 136 | issue = 1 | pages = 50–5 | date = January 2016 | pmid = 25800796 | doi = 10.1177/1757913915576679 | s2cid = 19400451 }}</ref> Myopia can be corrected with [[eyeglass]]es, [[contact lenses]], or by [[refractive surgery]].<ref name=NIH2010/><ref name="Short-sightedness myopia">{{Cite web |date=2017-10-23 |title=Short-sightedness (myopia) |url=https://www.nhs.uk/conditions/short-sightedness/ |access-date=2023-10-25 |website=nhs.uk |language=en}}</ref> Eyeglasses are the simplest and safest method of correction.<ref name=NIH2010/> Contact lenses can provide a relatively wider corrected [[field of vision]], but are associated with an increased risk of infection.<ref name=NIH2010/><ref>{{Cite web |date=2022-11-30 |title=Benefits of Vision Correction with Contact Lenses {{!}} Contact Lenses {{!}} CDC |url=https://www.cdc.gov/contactlenses/benefits.html |access-date=2023-10-25 |website=www.cdc.gov |language=en-us}}</ref> Refractive surgeries such as [[LASIK]] and [[Photorefractive keratectomy|PRK]] permanently change the shape of the [[cornea]]. Other procedures include [[implantable collamer lens]] (ICL) inside the anterior chamber in front of the natural eye lens. ICL doesn't affect the cornea.<ref name=NIH2010/><ref>{{Cite journal |last1=Chen |first1=Xun |last2=Wang |first2=Xiao-Ying |last3=Zhang |first3=Xi |last4=Chen |first4=Zhi |last5=Zhou |first5=Xing-Tao |date=2016-10-18 |title=Implantable collamer lens for residual refractive error after corneal refractive surgery |journal=International Journal of Ophthalmology |volume=9 |issue=10 |pages=1421–1426 |doi=10.18240/ijo.2016.10.09 |issn=2222-3959 |pmc=5075656 |pmid=27803858}}</ref>

<!-- Epidemiology -->
Myopia is the most common eye problem and is estimated to affect 1.5 billion people (22% of the world population).<ref name=Fos2014/><ref name=Hol2014>{{cite journal | vauthors = Holden B, Sankaridurg P, Smith E, Aller T, Jong M, He M | title = Myopia, an underrated global challenge to vision: where the current data takes us on myopia control | journal = Eye | volume = 28 | issue = 2 | pages = 142–6 | date = February 2014 | pmid = 24357836 | pmc = 3930268 | doi = 10.1038/eye.2013.256 }}</ref> Rates vary significantly in different areas of the world.<ref name=Fos2014/> Rates among adults are between 15% and 49%.<ref name=Pan2012>{{cite journal | vauthors = Pan CW, Ramamurthy D, Saw SM | title = Worldwide prevalence and risk factors for myopia | journal = Ophthalmic & Physiological Optics | volume = 32 | issue = 1 | pages = 3–16 | date = January 2012 | pmid = 22150586 | doi = 10.1111/j.1475-1313.2011.00884.x | s2cid = 32397628 | doi-access = free }}</ref><ref name=Pan2015/> Among children, it affects 1% of rural Nepalese, 4% of South Africans, 12% of people in the US, and 37% in some large Chinese cities.<ref name=Fos2014/><ref name=Pan2012/> In China the proportion of girls is slightly higher than boys.<ref name="pmid31259808">{{cite journal|vauthors=Dong L, Kang YK, Li Y, Wei WB, Jonas JB|date=March 2020|title=Prevalence And Time Trends Of Myopia In Children And Adolescents In China: A Systemic Review and Meta-Analysis|journal=Retina|volume=40|issue=3|pages=399–411|doi=10.1097/IAE.0000000000002590|pmid=31259808|s2cid=195756787}}</ref> Rates have increased since the 1950s.<ref name=Pan2015/> Uncorrected myopia is one of the most common causes of [[vision impairment]] globally along with [[cataract]]s, [[macular degeneration]], and [[vitamin A deficiency]].<ref name=Pan2015>{{cite journal | vauthors = Pan CW, Dirani M, Cheng CY, Wong TY, Saw SM | title = The age-specific prevalence of myopia in Asia: a meta-analysis | journal = Optometry and Vision Science | volume = 92 | issue = 3 | pages = 258–66 | date = March 2015 | pmid = 25611765 | doi = 10.1097/opx.0000000000000516 | s2cid = 42359341 | doi-access = free }}</ref><ref>{{Cite journal |last=Fredrick |first=Douglas R |date=2002-05-18 |title=Myopia |journal=BMJ: British Medical Journal |volume=324 |issue=7347 |pages=1195–1199 |doi=10.1136/bmj.324.7347.1195 |issn=0959-8138 |pmc=1123161 |pmid=12016188}}</ref><ref>{{Cite web |date=2023-09-29 |title=Common Eye Disorders and Diseases {{!}} CDC |url=https://www.cdc.gov/visionhealth/basics/ced/index.html |access-date=2023-10-25 |website=www.cdc.gov |language=en-us}}</ref><ref>{{Cite web |title=Vision impairment and blindness |url=https://www.who.int/news-room/fact-sheets/detail/blindness-and-visual-impairment |access-date=2023-10-25 |website=www.who.int |language=en}}</ref>
{{TOC limit|3}}

==Signs and symptoms==
{{multiple image
| align =
| image1 = Human eyesight two children and ball with myopia.jpg
| width1 = 200
| alt1 =
| caption1 =
| image2 = Human eyesight two children and ball normal vision color Hi-res.jpg
| width2 = 200
| alt2 =
| caption2 =
| footer = Near-sighted vision vs. normal vision
}}
A person with myopia can see clearly out to a certain distance (the [[far point]] of the eye), but objects placed beyond this distance appear [[Defocus aberration|blurred]].<ref name="Short-sightedness myopia"/><ref name="Carr 1995">{{Citation |last1=Carr |first1=Brittany J. |title=The Science Behind Myopia |date=1995 |url=http://www.ncbi.nlm.nih.gov/books/NBK470669/ |work=Webvision: The Organization of the Retina and Visual System |editor-last=Kolb |editor-first=Helga |access-date=2023-10-25 |place=Salt Lake City (UT) |publisher=University of Utah Health Sciences Center |pmid=29266913 |last2=Stell |first2=William K. |editor2-last=Fernandez |editor2-first=Eduardo |editor3-last=Nelson |editor3-first=Ralph}}</ref> If the extent of the myopia is great enough, even standard reading distances can be affected. Upon routine examination of the eyes, the vast majority of myopic eyes appear structurally identical to nonmyopic eyes.<ref>{{Cite journal |last=Hennelly |first=Michelle L |date=2019 |title=How to detect myopia in the eye clinic |journal=Community Eye Health |volume=32 |issue=105 |pages=15–16 |issn=0953-6833 |pmc=6688402 |pmid=31409949}}</ref><ref name="Carr 1995"/>

Onset is often in school children, with worsening between the ages of 8 and 15.<ref name=Val2019>{{cite journal | vauthors = Coviltir V, Burcel M, Cherecheanu AP, Ionescu C, Dascalescu D, Potop V, Burcea M | title = Update on Myopia Risk Factors and Microenvironmental Changes | journal = Journal of Ophthalmology | volume = 2019 | pages = 4960852 | date = 2019 | pmid = 31781378 | pmc = 6875023 | doi = 10.1155/2019/4960852 | doi-access = free }}</ref><ref>{{Cite journal |last1=Recko |first1=Matthew |last2=Stahl |first2=Erin Durrie |date=2015 |title=Childhood Myopia: Epidemiology, Risk Factors, and Prevention |journal=Missouri Medicine |volume=112 |issue=2 |pages=116–121 |issn=0026-6620 |pmc=6170055 |pmid=25958656}}</ref>

Myopic individuals have [[Mydriasis|larger pupils]] than far-sighted ([[Far-sightedness|hypermetropic]]) and [[Emmetropia|emmetropic]] individuals, likely due to requiring less accommodation (which results in pupil constriction).<ref>{{Cite journal |last1=Cakmak |first1=Hasan Basri |last2=Cagil |first2=Nurullah |last3=Simavlı |first3=Hüseyin |last4=Duzen |first4=Betul |last5=Simsek |first5=Saban |date=February 2010 |title=Refractive Error May Influence Mesopic Pupil Size |url=http://www.tandfonline.com/doi/full/10.3109/02713680903447892 |journal=Current Eye Research |language=en |volume=35 |issue=2 |pages=130–136 |doi=10.3109/02713680903447892 |pmid=20136423 |s2cid=27407880 |issn=0271-3683|url-access=subscription }}</ref><ref>{{Cite journal |last1=Zhu |first1=X |last2=Ye |first2=H |last3=Yang |first3=J |last4=Lu |first4=Y |date=2015 |title=Effect of pupil size on higher-order aberrations in high-myopic pseudophakic eyes with posterior staphyloma |journal=Eye |volume=29 |issue=1 |pages=98–105 |doi=10.1038/eye.2014.242 |issn=0950-222X |pmc=4289834 |pmid=25323850}}</ref>

==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>

==Mechanism==
Because myopia is a refractive error, the physical cause of myopia is comparable to any optical system that is out of focus. [[Irvin Borish|Borish]] and [[Stewart Duke-Elder|Duke-Elder]] classified myopia by these physical causes:<ref name="Borish">Borish, Irvin M. (1949). ''Clinical Refraction''. Chicago: The Professional Press.</ref><ref name="Duke-Elder">Duke-Elder, Sir Stewart (1969). ''The Practice of Refraction'' (8th ed.). St. Louis: The C.V. Mosby Company. {{ISBN|0-7000-1410-1}}.</ref>
* Axial myopia is attributed to an increase in the eye's axial length.<ref name="Cline">{{cite book| vauthors = Cline D, Hofstetter HW, Griffin JR |title=Dictionary of Visual Science|edition=4th|publisher=Butterworth-Heinemann |location=Boston|year=1997|isbn=978-0-7506-9895-5}}</ref>
* Refractive myopia is attributed to the condition of the [[Refraction|refractive]] elements of the eye.<ref name="Cline" /> Borish further subclassified refractive myopia:<ref name="Borish" />
** Curvature myopia is attributed to excessive, or increased, curvature of one or more of the refractive surfaces of the eye, especially the cornea.<ref name="Cline" /> In those with [[Cohen syndrome]], myopia appears to result from high corneal and lenticular power.<ref>{{cite journal | vauthors = Summanen P, Kivitie-Kallio S, Norio R, Raitta C, Kivelä T | title = Mechanisms of myopia in Cohen syndrome mapped to chromosome 8q22 | journal = Investigative Ophthalmology & Visual Science | volume = 43 | issue = 5 | pages = 1686–93 | date = May 2002 | pmid = 11980891 }}</ref>
** Index myopia is attributed to variation in the [[Refractive index|index of refraction]] of one or more of the ocular media.<ref name="Cline" />

As with any optical system experiencing a [[defocus aberration]], the effect can be exaggerated or masked by changing the [[F-number|aperture size]]. In the case of the eye, a large pupil emphasizes refractive error and a small pupil masks it. This phenomenon can cause a condition in which an individual has a greater difficulty seeing in low-illumination areas, even though there are no symptoms in bright light, such as daylight.<ref>The Eyecare Trust. ''[http://www.eye-care.org.uk/item_pdf.php?item_id=477 Night Driving – The Facts.]'' OR ''[http://www.eyecaretrust.org.uk/pdf/night_driving_final.pdf Eye care advice for driving in the dark] {{webarchive|url=https://web.archive.org/web/20120320054904/http://www.eyecaretrust.org.uk/pdf/night_driving_final.pdf|date=20 March 2012}}'' 26 January 2005.'<!--
ORIGINAL SOURCE WAS (but this didn't work as of 2011.10.01): http://www.eye-care.org.uk/item_view.php?item_id=52&content_id=3 Night Driving – The Facts.
--></ref>

Under rare conditions, edema of the [[ciliary body]] can cause an anterior displacement of the lens, inducing a myopia shift in refractive error.<ref name="Panday2007"/>

==Diagnosis==
A diagnosis of myopia is typically made by an [[eye care professional]], usually an [[Optometry|optometrist]] or [[Ophthalmology|ophthalmologist]]. This is by [[Refraction|refracting]] the [[eye]] with the use of [[Cycloplegia|cycloplegics]] such as [[atropine]] with responses recorded when [[Accommodation (vertebrate eye)|accommodation]] is relaxed.<ref name=":4" /> Diagnosis of progressive myopia requires regular [[eye examination]] using the same method.<ref name=":4" />

===Types===
Myopia can be classified into two major types; [[Anatomy|anatomical]] and clinical. The types of myopia based on anatomical features are axial, curvature, index and displacement of refractive element. [[Birth defect|Congenital]], simple and pathological myopia are the clinical types of myopia.<ref name=":6" />

Various forms of myopia have been described by their clinical appearance:<ref name="Duke-Elder" /><ref name="Goss">{{cite book| vauthors = Goss DA, Eskridge JB |chapter=Myopia| veditors = Amos JB |title=Diagnosis and management in vision care|publisher=Butterworths|location=Boston|year=1988|isbn=978-0-409-95082-3|page=445|oclc=14967262}}</ref><ref name="Richards1976">{{cite journal | vauthors = Richards OW | title = Instrument myopia--microscopy | journal = American Journal of Optometry and Physiological Optics | volume = 53 | issue = 10 | pages = 658–63 | date = October 1976 | pmid = 1015520 | doi = 10.1097/00006324-197610000-00003 | s2cid = 37513722 }}</ref>
* Simple myopia: Myopia in an otherwise normal eye, typically less than 4.00 to 6.00 [[Dioptre|diopters]].<ref name="AOA">{{cite report|author=American Optometric Association|year=1997|title=Optometric Clinical Practice Guideline: Care of the Patient with Myopia|url=http://www.aoa.org/documents/optometrists/CPG-15.pdf|url-status=dead|archive-url=https://web.archive.org/web/20150122062311/http://www.aoa.org/documents/optometrists/CPG-15.pdf|archive-date=22 January 2015|df=dmy-all|access-date=17 February 2015}}</ref> This is the most common form of myopia.
* Degenerative myopia, also known as malignant, pathological, or progressive myopia, is characterized by marked [[Fundus (eye)|fundus]] changes, such as posterior [[staphyloma]], and associated with a high [[refractive error]] and subnormal visual acuity after correction.<ref name="Cline" /> This form of myopia gets progressively worse over time. Degenerative myopia has been reported as one of the main causes of [[visual impairment]].<ref name="pmid12022735">{{cite journal | vauthors = Li CY, Lin KK, Lin YC, Lee JS | title = Low vision and methods of rehabilitation: a comparison between the past and present | journal = Chang Gung Medical Journal | volume = 25 | issue = 3 | pages = 153–61 | date = March 2002 | pmid = 12022735 }}</ref>
* [[Pseudomyopia]] is the blurring of distance vision brought about by [[spasm]] of the [[Accommodation (eye)|accommodation]] system.<ref name="Cassin">Cassin, B. and Solomon, S. (2001) ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company. {{ISBN|0937404632}}.</ref>
* Nocturnal myopia: Without adequate stimulus for accurate accommodation, the accommodation system partially engages, pushing distance objects out of focus.<ref name="AOA" />
* Nearwork-induced transient myopia (NITM): short-term myopic far point shift immediately following a sustained near visual task.<ref name="Ong">{{cite journal | vauthors = Ong E, Ciuffreda KJ | title = Nearwork-induced transient myopia: a critical review | journal = Documenta Ophthalmologica. Advances in Ophthalmology | volume = 91 | issue = 1 | pages = 57–85 | year = 1995 | pmid = 8861637 | doi = 10.1007/BF01204624 | s2cid = 2065074 }}</ref> Some authors argue for a link between NITM and the development of permanent myopia.<ref name="Ciuffreda">{{cite journal | vauthors = Ciuffreda KJ, Vasudevan B | title = Nearwork-induced transient myopia (NITM) and permanent myopia—is there a link? | journal = Ophthalmic & Physiological Optics | volume = 28 | issue = 2 | pages = 103–14 | date = March 2008 | pmid = 18339041 | doi = 10.1111/j.1475-1313.2008.00550.x | s2cid = 28700508 | doi-access = free }}</ref>
* [[Instrument myopia]]: over-accommodation when looking into an instrument such as a [[microscope]].<ref name="Richards1976" />
* Induced myopia, also known as acquired myopia, sometimes {{visible anchor|reversible myopic shift}}, results from various medications, increases in [[glucose]] levels, [[nuclear sclerosis]], [[oxygen toxicity]] (e.g., from [[underwater diving]] or from oxygen and [[hyperbaric therapy]]) or other anomalous conditions.<ref name="Bennett and Cooper 2022" >{{cite journal |url=https://www.ncbi.nlm.nih.gov/books/NBK470454/ |title=Hyperbaric Cataracts |first1=Michael H.  |last1=Bennett |first2=Jeffrey S. |last2=Cooper  |website=www.ncbi.nlm.nih.gov |publisher=StatPearls Publishing LLC. |pmid=29261974 |date=21 June 2022 |access-date=30 July 2022}}</ref><ref name="AOA" /> [[Sulfonamide (medicine)|Sulphonamide]] therapy can cause ciliary body edema, resulting in [[anterior]] displacement of the lens, pushing the eye out of focus.<ref name="Panday2007">{{cite journal | vauthors = Panday VA, Rhee DJ | title = Review of sulfonamide-induced acute myopia and acute bilateral angle-closure glaucoma | journal = Comprehensive Ophthalmology Update | volume = 8 | issue = 5 | pages = 271–6 | date = September 2007 | pmid = 18201514 | type = Review }}</ref> Elevation of [[Blood sugar level|blood-glucose]] levels can also cause edema (swelling) of the [[Lens (anatomy)|crystalline lens]] as a result of [[sorbitol]] accumulating in the lens. This edema often causes temporary myopia. [[Scleral buckle]]s, used in the repair of [[retinal detachment]]s may induce myopia by increasing the axial length of the eye.<ref>{{cite journal |last1=Vukojević |first1=Nenad |last2=Šikić |first2=Jakov |last3=Ćurković |first3=Tihomir |last4=Juratovac |first4=Zlatko |last5=Katušić |first5=Damir |last6=Šarić |first6=Borna |last7=Jukić |first7=Tomislav |title=Axial Eye Length after Retinal Detachment Surgery |journal=Collegium Antropologicum |date=20 June 2005 |volume=29 – Supplement 1 |issue=1 |pages=25–27 |pmid=16193671 |url=https://hrcak.srce.hr/27915 }}</ref>
* Index myopia is attributed to variation in the index of refraction of one or more of the ocular media.<ref name="Cline" /> Cataracts may lead to index myopia.<ref>{{cite journal | vauthors = Metge P, Donnadieu M | title = Myopie et cataracte |trans-title=Myopia and cataract | language = fr | journal = La Revue du Praticien | volume = 43 | issue = 14 | pages = 1784–6 | date = September 1993 | pmid = 8310218 |oclc=116851621 }}</ref>
* Form deprivation myopia occurs when the eyesight is deprived by limited illumination and vision range,<ref name="Young FA">{{cite journal | vauthors = Young FA | title = The effect of nearwork illumination level on monkey refraction | journal = American Journal of Optometry & Archives of American Academy of Optometry | volume = 39 | issue = 2 | pages = 60–7 | date = February 1962 | pmid = 14009334 | doi = 10.1097/00006324-196202000-00002 }}</ref> or the eye is modified with artificial lenses<ref name="Zhu et al.">{{cite journal | vauthors = Zhu X, Park TW, Winawer J, Wallman J | title = In a matter of minutes, the eye can know which way to grow | journal = Investigative Ophthalmology & Visual Science | volume = 46 | issue = 7 | pages = 2238–41 | date = July 2005 | pmid = 15980206 | doi = 10.1167/iovs.04-0956 | doi-access = free }}</ref> or deprived of clear form vision.<ref name="Wallman et al.">{{cite journal | vauthors = Wallman J, Gottlieb MD, Rajaram V, Fugate-Wentzek LA | title = Local retinal regions control local eye growth and myopia | journal = Science | volume = 237 | issue = 4810 | pages = 73–7 | date = July 1987 | pmid = 3603011 | doi = 10.1126/science.3603011 | bibcode = 1987Sci...237...73W | jstor = 1699607 | s2cid = 31790023 }}</ref> In lower vertebrates, this kind of myopia seems to be reversible within short periods of time. Myopia is often induced this way in various animal models to study the [[pathogenesis]] and mechanism of myopia development.<ref name="shen">{{cite journal | vauthors = Shen W, Vijayan M, Sivak JG | title = Inducing form-deprivation myopia in fish | journal = Investigative Ophthalmology & Visual Science | volume = 46 | issue = 5 | pages = 1797–803 | date = May 2005 | pmid = 15851585 | doi = 10.1167/iovs.04-1318 | doi-access = free }}</ref>

===Degree===
The degree of myopia is described in terms of the [[optical power|power]] of the ideal [[corrective lens|correction]], which is measured in [[Dioptre|diopters]]:<ref name="Grosvenor">{{cite journal | vauthors = Grosvenor T | title = A review and a suggested classification system for myopia on the basis of age-related prevalence and age of onset | journal = American Journal of Optometry and Physiological Optics | volume = 64 | issue = 7 | pages = 545–54 | date = July 1987 | pmid = 3307441 | doi = 10.1097/00006324-198707000-00012 }}</ref>
* Myopia between −0.00 and −0.50 diopters is usually classified as [[emmetropia]].
* Low myopia usually describes myopia between −0.50 and −3.00 diopters.<ref name="Cline" />
* Moderate myopia usually describes myopia between −3.00 and −6.00 [[diopters]].<ref name="Cline" /> Those with moderate amounts of myopia are more likely to have [[pigment dispersion syndrome]] or [[glaucoma|pigmentary glaucoma]].<ref>[http://www.eyemdlink.com/Condition.asp?ConditionID=2 "Glaucoma."] {{webarchive|url=https://web.archive.org/web/20060819160824/http://www.eyemdlink.com/Condition.asp?ConditionID=2 |date=19 August 2006 }} EyeMDLink.com. Retrieved 27 August 2006.</ref>
* High myopia usually describes myopia of −6.00 or more.<ref name="Cline" /><ref>{{cite journal |last1=Zejmo |first1=Maria |last2=Formińska-Kapuścik |first2=Maria |last3=Pieczara |first3=Ewa |last4=Filipek |first4=Erita |last5=Mrukwa-Kominek |first5=Ewa |last6=Samochowiec-Donocik |first6=Elzbieta |last7=Leszczyński |first7=Rafal |last8=Smuzyńska |first8=Magdalena |title=Etiopathogenesis and management of high-degree myopia. Part I |journal=Medical Science Monitor |date=September 2009 |volume=15 |issue=9 |pages=RA199-202 |pmid=19721411 |id={{INIST|21992936}} |url=https://www.medscimonit.com/abstract/index/idArt/878169 }}</ref> People with high myopia are more likely to have [[retinal detachment]]s<ref>{{EMedicine|article|798501|Retinal Detachment}}</ref> and [[glaucoma|primary open angle glaucoma]].<ref>[https://web.archive.org/web/20040204164358/http://www.agingeye.net/glaucoma/glaucomainformation.php "More Information on Glaucoma."] AgingEye Times. Retrieved 27 August 2006.</ref> They are also more likely to experience [[floater]]s, shadow-like shapes which appear in the [[visual field|field of vision]].<ref>{{cite journal | vauthors = Messmer DE | title = [Retinal detachment] | language = de | journal = Schweizerische Rundschau für Medizin Praxis = Revue Suisse de Médecine Praxis | volume = 81 | issue = 19 | pages = 622–5 | date = May 1992 | pmid = 1589678 }}</ref> In addition to this, high myopia is linked to macular degeneration, cataracts, and significant visual impairment.<ref>Banerjee S, Horton J. Lenses and Spectacles to Prevent Myopia Worsening in Children [Internet]. Ottawa (ON): Canadian Agency for Drugs and Technologies in Health; 2021 Apr. Available from:[https://www.ncbi.nlm.nih.gov/books/NBK571917/]</ref><ref>Walline JJ, Walker MK, Mutti DO, et al. Effect of High Add Power, Medium Add Power, or Single-Vision Contact Lenses on Myopia Progression in Children: The BLINK Randomized Clinical Trial. JAMA. 2020;324(6):571–580.</ref><ref>Ruiz-Pomeda A, Perez-Sanchez B, Valls I, Prieto-Garrido FL, Gutierrez-Ortega R, Villa-Collar C. MiSight Assessment Study Spain (MASS). A 2-year randomized clinical trial. Graefes Arch Clin Exp Ophthalmol. 2018;256(5):1011–1021.</ref><ref>Garcia-Del Valle AM, Blazquez V, Gros-Otero J, et al. Efficacy and safety of a soft contact lens to control myopia progression. Clin Exp Optom.2021;104(1):14–21</ref>
The highest myopia ever recorded was −108 diopters by a [[Slovakia|Slovak]], Jan Miskovic.<ref>{{cite web |last1=Fitoussi |first1=Stephane |title=The World Record of Myopia |date=23 May 2023 |url=https://fluorescene.odcommunity.com/11232-2/}}</ref>

===Age at onset===
Myopia is sometimes classified by the age at onset:<ref name="Grosvenor" />
* Congenital myopia, also known as infantile myopia, is present at birth and persists through infancy.<ref name="AOA" />
* Youth onset myopia occurs in early childhood or teenage, and the ocular power can keep varying until the age of 21, before which any form of corrective surgery is usually not recommended by ophthalmic specialists around the world.<ref name="AOA" />
* School myopia appears during childhood, particularly the school age years.<ref name="Morgan 1">{{cite journal | vauthors = Morgan I, Rose K | title = How genetic is school myopia? | journal = Progress in Retinal and Eye Research | volume = 24 | issue = 1 | pages = 1–38 | date = January 2005 | pmid = 15555525 | doi = 10.1016/j.preteyeres.2004.06.004 | s2cid = 18045281 }}</ref> This form of myopia is attributed to the use of the eyes for close work during the school years.<ref name="Cline" /> A 2004–2015 Singapore–Sydney study of children of Chinese descent found that time spent on outdoor activities was a factor.<ref>{{Cite web |url=http://www.smj.org.sg/article/school-based-programme-address-childhood-myopia-singapore |title=School based program |access-date=10 November 2022 |archive-date=10 November 2022 |archive-url=https://web.archive.org/web/20221110222346/http://www.smj.org.sg/article/school-based-programme-address-childhood-myopia-singapore |url-status=dead }}</ref>
* Adult onset myopia

:* Early adult onset myopia occurs between ages 20 and 40.<ref name="AOA" />
:*Late adult onset myopia occurs after age 40.<ref name="AOA" />

==Prevention and control==
Various methods have been employed in an attempt to decrease the progression of myopia, although studies show mixed results.<ref name="Saw 1">{{cite journal | vauthors = Saw SM, Gazzard G, Au Eong KG, Tan DT | title = Myopia: attempts to arrest progression | journal = The British Journal of Ophthalmology | volume = 86 | issue = 11 | pages = 1306–1311 | date = November 2002 | pmid = 12386095 | pmc = 1771373 | doi = 10.1136/bjo.86.11.1306 }}</ref> Many myopia treatment studies have a number of design drawbacks: [[Sample size determination|small numbers]], lack of adequate [[Scientific control|control]] group, and failure to [[Blind experiment|mask examiners]] from knowledge of treatments used. The best approach is to combine multiple prevention and control methods.<ref>{{Cite journal |last1=Zhang |first1=Guanghong |last2=Jiang |first2=Jun |last3=Qu |first3=Chao |date=2023-04-27 |title=Myopia prevention and control in children: a systematic review and network meta-analysis |journal=Eye |volume=37 |issue=16 |pages=3461–3469 |doi=10.1038/s41433-023-02534-8 |issn=1476-5454 |pmid=37106147|pmc=10630522 |s2cid=258376819 }}</ref> A test of repeated low-level red-light therapy (LLRL) on myopic Chinese children showed it to be a promising alternative treatment for myopia control in children.<ref>Jiang M.D., Yu,  et al., ''[https://www.aaojournal.org/article/S0161-6420(21)00916-7/fulltext Effect of Repeated Low-Level Red-Light Therapy for Myopia Control in Children]'', ''Ophthalmology'', American Academy of Ophthalmology, Volume 129, Issue 5P509-519, May 2022</ref>

=== Spending time outdoors ===
Some studies have indicated that having children spend time outdoors reduces the incidence of myopia.<ref name=":1">{{Cite journal |last1=Lawrenson |first1=John G. |last2=Shah |first2=Rakhee |last3=Huntjens |first3=Byki |last4=Downie |first4=Laura E. |last5=Virgili |first5=Gianni |last6=Dhakal |first6=Rohit |last7=Verkicharla |first7=Pavan K. |last8=Li |first8=Dongfeng |last9=Mavi |first9=Sonia |last10=Kernohan |first10=Ashleigh |last11=Li |first11=Tianjing |last12=Walline |first12=Jeffrey J. |date=2023-02-16 |title=Interventions for myopia control in children: a living systematic review and network meta-analysis |journal=The Cochrane Database of Systematic Reviews |volume=2023 |issue=2 |pages=CD014758 |doi=10.1002/14651858.CD014758.pub2 |issn=1469-493X |pmc=9933422 |pmid=36809645}}</ref> A 2017 study investigated the leading causal theory of association between greenspace exposure and spectacles use as a proxy for myopia, finding a 28% reduction in the likelihood of spectacles use per interquartile range increase in time spent in greenspace.<ref>{{Cite journal |last1=Sprague |first1=Nadav L. |last2=Bancalari |first2=Pilar |last3=Karim |first3=Wasie |last4=Siddiq |first4=Shabnaz |date=September 2022 |title=Growing up green: a systematic review of the influence of greenspace on youth development and health outcomes |journal=Journal of Exposure Science & Environmental Epidemiology |volume=32 |issue=5 |pages=660–681 |doi=10.1038/s41370-022-00445-6 |issn=1559-064X |pmc=9482936 |pmid=35614136|bibcode=2022JESEE..32..660S }}</ref> In Taiwan, government policies that require schools to send all children outdoors for a minimum amount of time have driven down the prevalence of myopia in children.<ref name=":1" /><ref name=":2">{{Cite magazine |last=Katwala |first=Amit |title=The World Is Going Blind. Taiwan Offers a Warning, and a Cure |language=en-US |magazine=Wired |url=https://www.wired.com/story/taiwan-epicenter-of-world-myopia-epidemic/ |access-date=2023-09-01 |issn=1059-1028}}</ref><!-- This popular magazine is offered in lieu of the old |laysource= parameter, to explain the research concepts and history in simpler language. -->

=== Glasses and contacts ===
The use of reading glasses when doing close work may improve vision by reducing or eliminating the need to accommodate. Altering the use of eyeglasses between full-time, part-time, and not at all does not appear to alter myopia progression.<ref name="pmid10416930">{{cite journal | vauthors = Ong E, Grice K, Held R, Thorn F, Gwiazda J | title = Effects of spectacle intervention on the progression of myopia in children | journal = Optometry and Vision Science | volume = 76 | issue = 6 | pages = 363–9 | date = June 1999 | pmid = 10416930 | doi = 10.1097/00006324-199906000-00015 }}</ref><ref name="pmid2667638">{{cite journal | vauthors = Pärssinen O, Hemminki E, Klemetti A | title = Effect of spectacle use and accommodation on myopic progression: final results of a three-year randomised clinical trial among schoolchildren | journal = The British Journal of Ophthalmology | volume = 73 | issue = 7 | pages = 547–51 | date = July 1989 | pmid = 2667638 | pmc = 1041798 | doi = 10.1136/bjo.73.7.547 }}</ref> The American Optometric Association's Clinical Practice Guidelines found evidence of effectiveness of bifocal lenses and recommends it as the method for "myopia control".<ref name="AOA" /> In some studies, bifocal and [[progressive lens]]es have not shown differences in altering the progression of myopia compared to placebo.<ref name="Saw 1" /><ref>{{Cite journal |last1=Wolffsohn |first1=James S. |last2=Flitcroft |first2=Daniel Ian |last3=Gifford |first3=Kate L. |last4=Jong |first4=Monica |last5=Jones |first5=Lyndon |last6=Klaver |first6=Caroline C. W. |last7=Logan |first7=Nicola S. |last8=Naidoo |first8=Kovin |last9=Resnikoff |first9=Serge |last10=Sankaridurg |first10=Padmaja |last11=Smith |first11=Earl L. |last12=Troilo |first12=David |last13=Wildsoet |first13=Christine F. |date=2019 |title=IMI – Myopia Control Reports Overview and Introduction |journal=Investigative Ophthalmology & Visual Science |volume=60 |issue=3 |pages=M1–M19 |doi=10.1167/iovs.18-25980 |issn=0146-0404 |pmc=6735780 |pmid=30817825}}</ref>

In the United States, the Food and Drug Administration (FDA) has approved myopia control contact lenses such as CooperVision’s MiSight and Johnson & Johnson Vision’s Acuvue Abiliti. Yet the agency has yet to approve any myopia control spectacle lenses.

===Medication===
[[muscarinic antagonist|Anti-muscarinic]] topical medications in children under 18 years of age may slow the worsening of myopia.<ref name="Walline">{{cite journal | vauthors = Walline JJ, Lindsley KB, Vedula SS, Cotter SA, Mutti DO, Ng SM, Twelker JD | title = Interventions to slow progression of myopia in children | journal = The Cochrane Database of Systematic Reviews | issue = 1 | pages = CD0O6460 | date = 2020 | volume = 1 | pmid = 31930781 | pmc = 6984636 | doi = 10.1002/14651858.CD004916.pub4 }}</ref><ref>{{cite journal | vauthors = Smith MJ, Walline JJ | title = Controlling myopia progression in children and adolescents | journal = Adolescent Health, Medicine and Therapeutics | volume = 6 | pages = 133–40 | date = 2015 | pmid = 26316834 | pmc = 4542412 | doi = 10.2147/AHMT.S55834 | doi-access = free }}</ref> These treatments include [[pirenzepine|pirenzepine gel]], [[cyclopentolate|cyclopentolate eye drops]], and [[atropine]] [[eye drops]]. While these treatments were shown to be effective in slowing the progression of myopia and reducing eyeball elongation associated with the condition, side effects included light sensitivity and near blur.<ref name="Walline" /><ref>{{Cite journal |last1=Li |first1=Fen Fen |last2=Yam |first2=Jason C. |date=2019-10-04 |title=Low-Concentration Atropine Eye Drops for Myopia Progression |journal=Asia-Pacific Journal of Ophthalmology |volume=8 |issue=5 |pages=360–365 |doi=10.1097/APO.0000000000000256 |issn=2162-0989 |pmc=6784858 |pmid=31478936}}</ref>

=== Other methods ===
[[Scleral reinforcement surgery]] is aimed to cover the thinning posterior pole with a supportive material to withstand [[intraocular pressure]] and prevent further progression of the posterior staphyloma. The strain is reduced, although damage from the pathological process cannot be reversed. By stopping the progression of the disease, vision may be maintained or improved.<ref name="ward">{{cite journal | vauthors = Ward B, Tarutta EP, Mayer MJ | title = The efficacy and safety of posterior pole buckles in the control of progressive high myopia | journal = Eye | volume = 23 | issue = 12 | pages = 2169–74 | date = December 2009 | pmid = 19229272 | doi = 10.1038/eye.2008.433 | doi-access = free }}</ref> The use of orthoK can also slow down axial lens elongation.<ref>{{Cite journal |last1=Wolffsohn |first1=James S. |last2=Flitcroft |first2=Daniel Ian |last3=Gifford |first3=Kate L. |last4=Jong |first4=Monica |last5=Jones |first5=Lyndon |last6=Klaver |first6=Caroline C. W. |last7=Logan |first7=Nicola S. |last8=Naidoo |first8=Kovin |last9=Resnikoff |first9=Serge |last10=Sankaridurg |first10=Padmaja |last11=Smith |first11=Earl L |last12=Troilo |first12=David |last13=Wildsoet |first13=Christine F. |date=2019 |title=IMI – Myopia Control Reports Overview and Introduction |journal=Investigative Ophthalmology & Visual Science |volume=60 |issue=3 |pages=19 |doi=10.1167/iovs.18-25980 |issn=0146-0404 |pmc=6735780 |pmid=30817825 }}</ref>

==Treatment==
[[File:Briller2.JPG|right|thumb|Glasses are commonly used to address myopia.]]The National Institutes of Health says there is no known way of preventing myopia, and the use of glasses or contact lenses does not affect its progression, unless the glasses or contact lenses are too strong of a prescription.<ref>[https://www.nlm.nih.gov/medlineplus/ency/article/001023.htm Near-sightedness] {{webarchive|url=https://web.archive.org/web/20160510130838/https://www.nlm.nih.gov/medlineplus/ency/article/001023.htm|date=10 May 2016}}. National Institutes of Health. 2010.</ref> There is no universally accepted method of preventing myopia and proposed methods need additional study to determine their effectiveness.<ref name="AOA" /> Optical correction using [[glasses]] or [[contact lens]]es is the most common treatment; other approaches include [[orthokeratology]], and [[refractive surgery]].<ref name="AOA" />{{rp|21–26}} Medications (mostly [[atropine]]) and [[vision therapy]] can be effective in addressing the various forms of [[pseudomyopia]]. [[File:Myopia and lens correction.svg|thumb|Compensating for myopia using a corrective lens]]

===Glasses and contacts===
{{multiple image
| align =
| image1 = Nearsighted color fringing -9.5 diopter - Canon PowerShot A640 thru glasses - overview.jpg
| width1 = 200
| alt1 =
| caption1 =
| image2 = Nearsighted color fringing -9.5 diopter - Canon PowerShot A640 thru glasses - closeup detail.jpg
| width2 = 200
| alt2 =
| caption2 =
| footer = Prismatic color distortion shown with a camera set for near-sighted focus, and using −9.5 [[diopter]] eyeglasses to correct the camera's myopia (''left''). Close-up of color shifting through corner of eyeglasses. The light and dark borders visible between color swatches do not exist (''right'').
}}

[[Corrective lens]]es [[Refraction|bend]] the light entering the eye in a way that places a focused image accurately onto the retina. The power of any lens system can be expressed in [[diopter]]s, the [[Multiplicative inverse|reciprocal]] of its [[focal length]] in meters. Corrective lenses for myopia have negative powers because a divergent lens is required to move the [[far point]] of focus out to the distance. More severe myopia needs lens powers further from zero (more negative). However, strong eyeglass prescriptions create distortions such as prismatic movement and [[chromatic aberration]]. Strongly myopic wearers of [[contact lens]]es do not experience these distortions because the lens moves with the cornea, keeping the optic axis in line with the visual axis and because the vertex distance has been reduced to zero.

===Surgery===
[[Refractive surgery]] includes procedures which alter the corneal curvature of some structure of the eye or which add additional refractive means inside the eye.

====Photorefractive keratectomy====
{{see also|Photorefractive keratectomy}}
Photorefractive keratectomy (PRK) involves ablation of corneal tissue from the corneal surface using an [[excimer laser]]. The amount of tissue ablation corresponds to the amount of myopia. While PRK is a relatively safe procedure for up to 6 dioptres of myopia, the recovery phase post-surgery is usually painful.<ref>{{cite journal | vauthors = Trokel SL, Srinivasan R, Braren B | title = Excimer laser surgery of the cornea | journal = American Journal of Ophthalmology | volume = 96 | issue = 6 | pages = 710–5 | date = December 1983 | pmid = 6660257 | doi = 10.1016/s0002-9394(14)71911-7 }}</ref><ref>{{cite journal | vauthors = Seiler T, Bende T, Wollensak J, Trokel S | title = Excimer laser keratectomy for correction of astigmatism | journal = American Journal of Ophthalmology | volume = 105 | issue = 2 | pages = 117–24 | date = February 1988 | pmid = 3341427 | doi = 10.1016/0002-9394(88)90173-0 }}</ref>

====LASIK====
In a [[LASIK]] pre-procedure, a corneal flap is cut into the cornea and lifted to allow the excimer laser beam access to the exposed corneal tissue. After that, the excimer laser ablates the tissue according to the required correction. When the flap again covers the cornea, the change in curvature generated by the laser ablation proceeds to the corneal surface. Though LASIK is usually painless and involves a short rehabilitation period post-surgery, it can potentially result in flap complications and loss of corneal stability (post-LASIK [[keratectasia]]).<ref>{{cite journal | vauthors = Pallikaris IG, Siganos DS | title = Laser in situ keratomileusis to treat myopia: early experience | journal = Journal of Cataract and Refractive Surgery | volume = 23 | issue = 1 | pages = 39–49 | year = 1997 | pmid = 9100106 | doi = 10.1016/s0886-3350(97)80149-6 | s2cid = 38655546 }}</ref><ref>{{cite journal | vauthors = Pallikaris IG, Kymionis GD, Astyrakakis NI | title = Corneal ectasia induced by laser in situ keratomileusis | journal = Journal of Cataract and Refractive Surgery | volume = 27 | issue = 11 | pages = 1796–802 | date = November 2001 | pmid = 11709254 | doi = 10.1016/s0886-3350(01)01090-2 | s2cid = 2333450 }}</ref>

====Phakic intra-ocular lens====
Instead of modifying the corneal surface, as in laser vision correction (LVC), this procedure involves implanting an additional lens inside the eye (i.e., in addition to the already existing natural lens). While it usually results in good control of the refractive change, it can induce potential serious long-term complications such as glaucoma, cataract and endothelial decompensation.<ref>{{cite journal | vauthors = Menezo JL, Peris-Martínez C, Cisneros-Lanuza AL, Martínez-Costa R | title = Rate of cataract formation in 343 highly myopic eyes after implantation of three types of phakic intraocular lenses | journal = Journal of Refractive Surgery | volume = 20 | issue = 4 | pages = 317–24 | year = 2004 | pmid = 15307392 | doi = 10.3928/1081-597X-20040701-03 }}</ref><ref>{{cite journal | vauthors = Torun N, Bertelmann E, Klamann MK, Maier AK, Liekfeld A, Gonnermann J | title = Posterior chamber phakic intraocular lens to correct myopia: long-term follow-up | journal = Journal of Cataract and Refractive Surgery | volume = 39 | issue = 7 | pages = 1023–8 | date = July 2013 | pmid = 23664355 | doi = 10.1016/j.jcrs.2013.01.041 | s2cid = 31750663 }}</ref><ref>{{cite journal | vauthors = Moshirfar M, Imbornoni LM, Ostler EM, Muthappan V | title = Incidence rate and occurrence of visually significant cataract formation and corneal decompensation after implantation of Verisyse/Artisan phakic intraocular lens | journal = Clinical Ophthalmology | volume = 8 | pages = 711–6 | year = 2014 | pmid = 24748765 | pmc = 3986296 | doi = 10.2147/OPTH.S59878 | doi-access = free }}</ref>

===Orthokeratology===
{{main|Orthokeratology}}
Orthokeratology or simply Ortho-K is a temporary corneal reshaping process using rigid gas permeable (RGP) contact lenses.<ref>{{cite web |title=Orthokeratology (Ortho-k) – Corneal Reshaping with GP Contacts |url=https://www.contactlenses.org/orthok.htm |website=www.contactlenses.org}}</ref> Overnight wearing of specially designed contact lenses will temporarily reshape cornea, so patients may see clearly without any lenses in daytime. Orthokeratology can correct myopia up to −6D.<ref name="OW-OK">{{cite web |title=Orthokeratology: A Heated Debate Continues |url=https://www.ophthalmologyweb.com/Tech-Spotlights/26435-Orthokeratology-A-Heated-Debate-Continues/ |website=www.ophthalmologyweb.com |language=en}}</ref> Several studies shown that Ortho-K can reduce myopia progression also.<ref name="AAO-OK">{{cite web |title=Orthokeratology slows myopic progression in young patients |url=https://www.aao.org/editors-choice/orthokeratology-slows-myopic-progression-in-young- |website=American Academy of Ophthalmology |language=en |date=17 April 2019}}</ref><ref name="MPC-OK">{{cite web |title=Orthokeratology (Ortho-K) treatment for Myopia Prevention and Control |url=http://www.myopiaprevention.org/orthokeratology.html |website=www.myopiaprevention.org |access-date=4 June 2020 |archive-date=6 February 2020 |archive-url=https://web.archive.org/web/20200206215037/http://www.myopiaprevention.org/orthokeratology.html |url-status=dead }}</ref> Risk factors of using Ortho-K lenses include microbial keratitis,<ref name="AAO-OK" /> corneal edema,<ref name="RO-OK">{{cite web | vauthors = Daniels K |title=Consider Ortho-K For Myopia Control |url=https://www.reviewofoptometry.com/article/consider-ortho-k-for-myopia-control#:~:text=Safety%20Concerns%20and%20Side%20Effects&text=As%20with%20all%20contact%20lens,ocular%20abrasion%20or%20visual%20distortion. |website=www.reviewofoptometry.com}}</ref> etc. Other contact lens related complications such as corneal aberration, photophobia, pain, irritation, redness etc. are usually temporary conditions, which may be eliminated by proper usage of lenses.<ref name="RO-OK" />

===Intrastromal corneal ring segment===
The [[Intrastromal corneal ring segment]] (ICRS), commonly used in [[keratoconus]] treatment now, was originally designed to correct mild to moderate myopia.<ref>{{cite journal | vauthors = Vega-Estrada A, Alio JL | title = The use of intracorneal ring segments in keratoconus | journal = Eye and Vision | volume = 3 | pages = 8 | date = 15 March 2016 | pmid = 26981548 | pmc = 4791885 | doi = 10.1186/s40662-016-0040-z | doi-access = free }}</ref> The thickness is directly related to flattening and the diameter of the ring is proportionally inverse to the flattening of cornea. So, if diameter is smaller or thickness is greater, resulting myopia correction will be greater.<ref name="AAO-ICRS">{{cite web | vauthors = Pathak AK, Villarreal Gonzalez AJ, Karacal H |title=ICRS: Corneal biomechanics effects |url= https://eyewiki.aao.org/ICRS%3A_Corneal_biomechanics_effects#:~:text=Thus%2C%20the%20smaller%20the%20diameter,thickness)%20with%20higher%20myopic%20correction.&text=This%20flattening%20effect%20on%20the,separation%20and%20increased%20corneal%20flattening.}}</ref>

===Alternative medicine===
A number of [[alternative medicine|alternative therapies]] have been claimed to improve myopia, including [[vision therapy]], "behavioural optometry", various eye exercises and relaxation techniques, and the [[Bates method]].<ref name="Bates">Bates, Wm H (1920) [https://en.wikisource.org/wiki/Perfect_Sight_Without_Glasses/Chapter_10 Sight Without Glasses] {{webarchive|url=https://web.archive.org/web/20161220174710/https://en.wikisource.org/wiki/Perfect_Sight_Without_Glasses/Chapter_10 |date=20 December 2016 }}. Ch. 10, p. 106. {{ISBN|1479118540}}.</ref> Scientific reviews have concluded that there was "no clear scientific evidence" that eye exercises are effective in treating myopia<ref name="Rawstron">{{cite journal | vauthors = Rawstron JA, Burley CD, Elder MJ | title = A systematic review of the applicability and efficacy of eye exercises | journal = Journal of Pediatric Ophthalmology and Strabismus | volume = 42 | issue = 2 | pages = 82–8 | year = 2005 | doi = 10.3928/01913913-20050301-02 | pmid = 15825744 }}</ref> and as such they "cannot be advocated".<ref name="Barrett">{{cite journal | vauthors = Barrett BT | title = A critical evaluation of the evidence supporting the practice of behavioural vision therapy | journal = Ophthalmic & Physiological Optics | volume = 29 | issue = 1 | pages = 4–25 | date = January 2009 | pmid = 19154276 | doi = 10.1111/j.1475-1313.2008.00607.x | s2cid = 13588501 | doi-access = free }}</ref>

==Epidemiology==
Global refractive errors have been estimated to affect 800 million to 2.3 billion.<ref>Dunaway D, Berger I. [http://www.infocusonline.org/WORLDWIDE%20DISTRIBUTION%20OF%20VISUAL%20REFRACTIVE%20ERROR1.doc "Worldwide Distribution of Visual Refractive Errors and What to Expect at a Particular Location"] {{webarchive|url=https://web.archive.org/web/20070129083808/http://www.infocusonline.org/WORLDWIDE%20DISTRIBUTION%20OF%20VISUAL%20REFRACTIVE%20ERROR1.doc |date=29 January 2007 }}. infocusonline.org.</ref> The incidence of myopia within sampled population often varies with age, country, sex, [[Race (classification of human beings)|race]], [[ethnicity]], occupation, environment, and other factors.<ref name="Verma">{{EMedicine|article|1221908|Phakic Intraocular Lens (IOL) for Myopia Correction}}</ref><ref name="Fredrick">{{cite journal | vauthors = Fredrick DR | title = Myopia | journal = BMJ | volume = 324 | issue = 7347 | pages = 1195–9 | date = May 2002 | pmid = 12016188 | pmc = 1123161 | doi = 10.1136/bmj.324.7347.1195 }}</ref> Variability in testing and data collection methods makes comparisons of prevalence and progression difficult.<ref>National Research Council Commission (1989). [http://www.nap.edu/openbook.php?isbn=0309040817 ''Myopia: Prevalence and Progression''] {{webarchive|url=https://web.archive.org/web/20140106040640/http://www.nap.edu/openbook.php?isbn=0309040817|date=6 January 2014}}, Washington, D.C.: National Academy Press, {{ISBN|0-309-04081-7}}</ref>

The prevalence of myopia has been reported as high as 70–90% in some [[Asia]]n countries, 30–40% in Europe and the United States, and 10–20% in Africa.<ref name="Fredrick" /> Myopia is about twice as common in [[Jewish people]] than in people of non-Jewish ethnicity.<ref name="Jensen">[[Arthur Jensen|Jensen, A.R.]] (1998) ''[[The g Factor: The Science of Mental Ability|The g Factor]]''. Westport, Connecticut: Praeger Publishers, {{ISBN|0275961036}}</ref> Myopia is less common in [[List of ethnic groups of Africa|African]] people and associated diaspora.<ref name="Verma" /> In Americans between the ages of 12 and 54, myopia has been found to affect [[African Americans]] less than Caucasians.<ref name="Sperduto">{{cite journal | vauthors = Sperduto RD, Seigel D, Roberts J, Rowland M | title = Prevalence of myopia in the United States | journal = Archives of Ophthalmology | volume = 101 | issue = 3 | pages = 405–7 | date = March 1983 | pmid = 6830491 | doi = 10.1001/archopht.1983.01040010405011 }}</ref>

A 2024 study published in the ''[[British Journal of Ophthalmology]]'' revealed that more than one-third of children worldwide were nearsighted in 2023, with this figure projected to rise to nearly 40% by 2050.<ref>{{Cite journal |last1=Liang |first1=Jinghong |last2=Pu |first2=Yingqi |last3=Chen |first3=Jiaqi |last4=Liu |first4=Meiling |last5=Ouyang |first5=Bowen |last6=Jin |first6=Zhengge |last7=Ge |first7=Wenxin |last8=Wu |first8=Zhuowen |last9=Yang |first9=Xiuzhi |last10=Qin |first10=Chunsong |last11=Wang |first11=Cong |last12=Huang |first12=Shan |last13=Jiang |first13=Nan |last14=Hu |first14=Lixin |last15=Zhang |first15=Yushan |date=2024-08-14 |title=Global prevalence, trend and projection of myopia in children and adolescents from 1990 to 2050: a comprehensive systematic review and meta-analysis |url=https://bjo.bmj.com/content/early/2024/08/14/bjo-2024-325427 |journal=British Journal of Ophthalmology |volume=109 |issue=3 |pages=362–371 |language=en |doi=10.1136/bjo-2024-325427 |issn=0007-1161 |pmid=39317432|url-access=subscription }}</ref> The prevalence of myopia among children and adolescents has increased significantly over the past 30 years, rising from 24% in 1990 to almost 36% in 2023, with researchers noting a sharp spike in cases following the [[COVID-19 pandemic]] and highlighting regional differences in myopia rates.<ref>{{Cite web |last=Guy |first=Jack |date=2024-09-25 |title=1 in 3 children worldwide is now nearsighted, study shows |url=https://www.cnn.com/2024/09/25/health/global-myopia-research-scli-intl-wellness/index.html |access-date=2024-09-29 |website=CNN |language=en}}</ref>

A 2025 South Korean analysis of 45 studies, involving 335,524 participants and largely based on data from children, adolescents and young adults, that looked at the use of digital screen devices such as mobile phones, game consoles and television, revealed that an additional hour of daily screen time is, on average, associated with 21% higher odds of having myopia.<ref>{{Cite web |last=Davis |first=Nicola |date=20 February 2025 |title=Every hour children spend on screens raises chance of myopia, study finds |url=https://www.theguardian.com/society/2025/feb/21/every-hour-children-spend-on-screens-raises-chance-of-myopia-study-finds |access-date=20 February 2025 |website=The Guardian}}</ref>

===Asia===
[[File:Estimated myopia rate in 20-year-olds in Asia.svg|thumb|upright=1.8|Estimated myopia rate in 20-year-olds in Asia<ref>{{cite journal | vauthors = Morgan IG, French AN, Ashby RS, Guo X, Ding X, He M, Rose KA | title = The epidemics of myopia: Aetiology and prevention | journal = Progress in Retinal and Eye Research | volume = 62 | pages = 134–149 | date = January 2018 | pmid = 28951126 | doi = 10.1016/j.preteyeres.2017.09.004 | hdl = 1885/139488 | s2cid = 9323449 | hdl-access = free }}</ref>]]
In some parts of [[Asia]], myopia is very common.
* [[Singapore]] is believed to have the highest prevalence of myopia in the world; up to 80% of people there have myopia, but the accurate figure is unknown.<ref>{{cite web |url=http://www.disabled-world.com/disability/types/vision/near-sighted-gene.php |title=Discovery of Gene May Provide Treatment for Near-sightedness |publisher=Disabled-world.com |date=12 September 2010 |access-date=2 August 2012 }}{{Dead link|date=February 2022 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>
* [[China]]'s myopia rate is 31%: 400 million of its 1.3 billion people are myopic. The prevalence of myopia in [[High school (upper secondary)|high school]] in China is 77%, and in [[college]] is more than 80%.<ref>[http://news.xinhuanet.com/politics/2010-01/03/content_12745349.htm 全国近视眼人数近4亿 近视已影响国人健康] {{webarchive|url=https://web.archive.org/web/20121027081348/http://news.xinhuanet.com/politics/2010-01/03/content_12745349.htm |date=27 October 2012 }}. Xinhua News Agency. Retrieved on 21 April 2013.</ref>
* In some areas, such as China and [[Malaysia]], up to 41% of the adult population is myopic to 1.00 dpt,<ref>{{cite journal | vauthors = Chandran S | title = Comparative study of refractive errors in West Malaysia | journal = The British Journal of Ophthalmology | volume = 56 | issue = 6 | pages = 492–5 | date = June 1972 | pmid = 5069190 | pmc = 1208824 | doi = 10.1136/bjo.56.6.492 }}</ref> and up to 80% to 0.5 dpt.<ref>{{cite journal | vauthors = Wu HM, Seet B, Yap EP, Saw SM, Lim TH, Chia KS | title = Does education explain ethnic differences in myopia prevalence? A population-based study of young adult males in Singapore | journal = Optometry and Vision Science | volume = 78 | issue = 4 | pages = 234–9 | date = April 2001 | pmid = 11349931 | doi = 10.1097/00006324-200104000-00012 | s2cid = 46445087 }}</ref>
* A study of Jordanian adults aged 17 to 40 found more than half (54%) were myopic.<ref name="pmid15953114">{{cite journal | vauthors = Mallen EA, Gammoh Y, Al-Bdour M, Sayegh FN | title = Refractive error and ocular biometry in Jordanian adults | journal = Ophthalmic & Physiological Optics | volume = 25 | issue = 4 | pages = 302–9 | date = July 2005 | pmid = 15953114 | doi = 10.1111/j.1475-1313.2005.00306.x | s2cid = 24694696 }}</ref>
* A study indicated that the prevalence of myopia among urban children in [[India]] of aged 5 to 15 increased from 4.44% in 1999 to 21.15% in 2019. Projections suggest that by 2050, this figure could reach 48.14%.<ref>{{Cite journal |last1=Priscilla |first1=Jacinth J. |last2=Verkicharla |first2=Pavan K. |date=May 2021 |title=Time trends on the prevalence of myopia in India – A prediction model for 2050 |url=https://pubmed.ncbi.nlm.nih.gov/33860952/ |journal=Ophthalmic & Physiological Optics: The Journal of the British College of Ophthalmic Opticians (Optometrists) |volume=41 |issue=3 |pages=466–474 |doi=10.1111/opo.12806 |issn=1475-1313 |pmid=33860952}}</ref> 
* Some research suggests the prevalence of myopia in Indian children is less than 15%.<ref name="pmid2853533">{{cite journal | vauthors = Saxena R, Vashist P, Tandon R, Pandey RM, Bhardawaj A, Gupta V, Menon V | title = Incidence and progression of myopia and associated factors in urban school children in Delhi: The North India Myopia Study (NIM Study) | journal = PLOS ONE | volume = 12 | issue = 12 | pages = e0189774 | date = 2017 | pmid = 29253002 | pmc = 5734754 | doi = 10.1371/journal.pone.0189774 | doi-access = free | bibcode = 2017PLoSO..1289774S }}</ref> 
* In [[South Korea]] among the general population, national data indicates that 70.6% of the adult population has myopia, with 8.0% affected by high myopia. The prevalence decreases with age, from 81.3% in individuals aged 19 to 24 years to 55.2% in those aged 45 to 49 years.<ref>{{Cite journal |title=Prevalence and risk factors of myopia in adult Korean population: Korea national health and nutrition examination survey 2013–2014 (KNHANES VI) |date=2019 |pmc=6345425 |journal=PLOS ONE |volume=14 |issue=1 |pages=e0211204 |doi=10.1371/journal.pone.0211204 |doi-access=free |pmid=30677087 |bibcode=2019PLoSO..1411204H | vauthors = Han SB, Jang J, Yang HK, Hwang J, Park SK }}</ref>
* Up to 90% of young people in Taiwan have myopia.<ref>{{Cite web |last=Davidson |first=Helen |date=28 February 2025 |title=Shortsighted Taiwan may have lessons for the world as a preventable disease skyrockets |url=https://www.theguardian.com/world/2025/mar/01/shortsighted-taiwan-may-have-lessons-for-the-world-as-a-preventable-disease-skyrockets |access-date=10 March 2025 |website=The Guardian}}</ref>

===Europe===
[[File:Myopia rate in Europe by birth decade.svg|thumb|upright=1.8|Myopia rate in Europe by birth decade (1910 to 1970)<ref>{{cite journal | vauthors = Williams KM, Bertelsen G, Cumberland P, Wolfram C, Verhoeven VJ, Anastasopoulos E, Buitendijk GH, Cougnard-Grégoire A, Creuzot-Garcher C, Erke MG, Hogg R, Höhn R, Hysi P, Khawaja AP, Korobelnik JF, Ried J, Vingerling JR, Bron A, Dartigues JF, Fletcher A, Hofman A, Kuijpers RW, Luben RN, Oxele K, Topouzis F, von Hanno T, Mirshahi A, Foster PJ, van Duijn CM, Pfeiffer N, Delcourt C, Klaver CC, Rahi J, Hammond CJ | display-authors = 6 | title = Increasing Prevalence of Myopia in Europe and the Impact of Education | journal = Ophthalmology | volume = 122 | issue = 7 | pages = 1489–97 | date = July 2015 | pmid = 25983215 | pmc = 4504030 | doi = 10.1016/j.ophtha.2015.03.018 }}</ref>]]
* In first-year undergraduate students in the United Kingdom 50% of [[United Kingdom|British]] whites and 53% of British Asians were myopic.<ref name="pmid15829853">{{cite journal | vauthors = Logan NS, Davies LN, Mallen EA, Gilmartin B | title = Ametropia and ocular biometry in a U.K. university student population | journal = Optometry and Vision Science | volume = 82 | issue = 4 | pages = 261–6 | date = April 2005 | pmid = 15829853 | doi = 10.1097/01.OPX.0000159358.71125.95 | s2cid = 25384178 }}</ref>
* A recent review found 27% of Western Europeans aged 40 or older have at least −1.00 diopters of myopia and 5% have at least −5.00 diopters.<ref name="pmid15078666" />

===North America===
Myopia is common in the [[United States]], with research suggesting this condition has increased dramatically in recent decades. In 1971–1972, the National Health and Nutrition Examination Survey provided the earliest nationally representative estimates for myopia prevalence in the U.S., and found the prevalence in persons aged 12–54 was 25%. Using the same method, in 1999–2004, myopia prevalence was estimated to have climbed to 42%.<ref name="Vitale">{{cite journal | vauthors = Vitale S, Sperduto RD, Ferris FL | title = Increased prevalence of myopia in the United States between 1971–1972 and 1999–2004 | journal = Archives of Ophthalmology | volume = 127 | issue = 12 | pages = 1632–9 | date = December 2009 | pmid = 20008719 | doi = 10.1001/archophthalmol.2009.303 | doi-access = free }}</ref>

A study of 2,523 children in grades 1 to 8 (age, 5–17 years) found nearly one in 10 (9%) have at least −0.75 diopters of myopia.<ref name="pmid12912692">{{cite journal | vauthors = Kleinstein RN, Jones LA, Hullett S, Kwon S, Lee RJ, Friedman NE, Manny RE, Mutti DO, Yu JA, Zadnik K | display-authors = 6 | title = Refractive error and ethnicity in children | journal = Archives of Ophthalmology | volume = 121 | issue = 8 | pages = 1141–7 | date = August 2003 | pmid = 12912692 | doi = 10.1001/archopht.121.8.1141 | doi-access = free }}</ref> In this study, 13% had at least +1.25 D [[hyperopia]] (farsightedness), and 28% had at least 1.00-D difference between the two principal meridians (cycloplegic autorefraction) of [[astigmatism]]. For myopia, Asians had the highest prevalence (19%), followed by Hispanics (13%). Caucasian children had the lowest prevalence of myopia (4%), which was not significantly different from African Americans (7%).<ref name="pmid12912692" />

A recent review found 25% of Americans aged 40 or older have at least −1.00 diopters of myopia and 5% have at least −5.00 diopters.<ref name="pmid15078666" />

===Australia===
In [[Australia]], the overall prevalence of myopia (worse than −0.50 diopters) has been estimated to be 17%.<ref name="pmid10326965">{{cite journal | vauthors = Wensor M, McCarty CA, Taylor HR | title = Prevalence and risk factors of myopia in Victoria, Australia | journal = Archives of Ophthalmology | volume = 117 | issue = 5 | pages = 658–63 | date = May 1999 | pmid = 10326965 | doi = 10.1001/archopht.117.5.658 | doi-access = free }}</ref> In one recent study, less than one in 10 (8%) Australian children between the ages of four and 12 were found to have myopia greater than −0.50 diopters.<ref name="pmid15705207">{{cite journal | vauthors = Junghans BM, Crewther SG | title = Little evidence for an epidemic of myopia in Australian primary school children over the last 30 years | journal = BMC Ophthalmology | volume = 5 | pages = 1 | date = February 2005 | pmid = 15705207 | pmc = 552307 | doi = 10.1186/1471-2415-5-1 | df = dmy-all | doi-access = free }}</ref> A recent review found 16% of Australians aged 40 or older have at least −1.00 diopters of myopia and 3% have at least −5.00 diopters.<ref name="pmid15078666">{{cite journal | vauthors = Kempen JH, Mitchell P, Lee KE, Tielsch JM, Broman AT, Taylor HR, Ikram MK, Congdon NG, O'Colmain BJ | display-authors = 6 | title = The prevalence of refractive errors among adults in the United States, Western Europe, and Australia | journal = Archives of Ophthalmology | volume = 122 | issue = 4 | pages = 495–505 | date = April 2004 | pmid = 15078666 | doi = 10.1001/archopht.122.4.495 | author10 = Eye Diseases Prevalence Research Group | doi-access = free }}</ref>

===South America===
In [[Brazil]], a 2005 study estimated 6% of Brazilians between the ages of 12 and 59 had −1.00 diopter of myopia or more, compared with 3% of the indigenous people in northwestern Brazil.<ref name="pmid15829854">{{cite journal | vauthors = Thorn F, Cruz AA, Machado AJ, Carvalho RA | title = Refractive status of indigenous people in the northwestern Amazon region of Brazil | journal = Optometry and Vision Science | volume = 82 | issue = 4 | pages = 267–72 | date = April 2005 | pmid = 15829854 | doi = 10.1097/01.OPX.0000159371.25986.67 | s2cid = 38979284 }}</ref> Another found nearly 1 in 8 (13%) of the students in the city of [[Natal, Rio Grande do Norte|Natal]] were myopic.<ref name="pmid16059562">{{cite journal | vauthors = Garcia CA, Oréfice F, Nobre GF, Souza D, Rocha ML, Vianna RN | title = [Prevalence of refractive errors in students in Northeastern Brazil] | journal = Arquivos Brasileiros de Oftalmologia | volume = 68 | issue = 3 | pages = 321–5 | date = June 2005 | pmid = 16059562 | doi = 10.1590/S0004-27492005000300009 | doi-access = free }}</ref>

==History==
The difference between the near-sighted and far-sighted people was noted already by [[Aristotle]].<ref name="myopia">{{cite book | veditors = Spaide RF, Ohno-Matsui KM, Yannuzzi LA | title =Pathologic Myopia| url = https://books.google.com/books?id=X1u4BAAAQBAJ| publisher =Springer Science & Business Media| year = 2013| page =2| isbn =978-1461483380}}</ref> Graeco-Roman physician [[Galen]] first used the term "myopia" (from Greek words "myein" meaning "to close or shut" and "ops" (gen. opos) meaning "eye") for near-sightedness.<ref name="myopia" /> The first spectacles for correcting myopia were invented by a German cardinal in the year 1451.<ref>{{cite web |title=Myopia – Birth Story |url=http://birthstory.net/tag/myopia/ |access-date=1 June 2020 |archive-date=20 April 2016 |archive-url=https://web.archive.org/web/20160420115527/http://birthstory.net/tag/myopia/ |url-status=dead }}</ref> [[Johannes Kepler]] in his ''Clarification of Ophthalmic Dioptrics'' (1604) first demonstrated that myopia was due to the incident light focusing in front of the retina. Kepler also showed that myopia could be corrected by concave lenses.<ref name="myopia" /> In 1632, [[Vopiscus Fortunatus Plempius]] examined a myopic eye and confirmed that myopia was due to a lengthening of its axial diameter.<ref>{{cite journal | vauthors = Dunphy EB | title = The biology of myopia | journal = The New England Journal of Medicine | volume = 283 | issue = 15 | pages = 796–800 | date = October 1970 | pmid = 4917270 | doi = 10.1056/NEJM197010082831507 }}</ref>

The idea that myopia was caused by the [[eye strain]] involved in reading or doing other work close to the eyes was a consistent theme for several centuries.<ref name=":2" />  In Taiwan, faced with a staggering rise in the number of young military recruits needing glasses, the schools were told to give students' eyes a 10-minute break after every half-hour of reading; however, the rate of myopia continued to climb.<ref name=":2" /><ref name=":3">{{Cite journal |last1=Jonas |first1=Jost B. |last2=Ang |first2=Marcus |last3=Cho |first3=Pauline |last4=Guggenheim |first4=Jeremy A. |last5=He |first5=Ming Guang |last6=Jong |first6=Monica |last7=Logan |first7=Nicola S. |last8=Liu |first8=Maria |last9=Morgan |first9=Ian |last10=Ohno-Matsui |first10=Kyoko |last11=Pärssinen |first11=Olavi |last12=Resnikoff |first12=Serge |last13=Sankaridurg |first13=Padmaja |last14=Saw |first14=Seang-Mei |last15=Smith |first15=Earl L. |date=2021-04-28 |title=IMI Prevention of Myopia and Its Progression |journal=Investigative Ophthalmology & Visual Science |volume=62 |issue=5 |pages=6 |doi=10.1167/iovs.62.5.6 |issn=1552-5783 |pmc=8083117 |pmid=33909032}}</ref>  The policy that reversed the epidemic of myopia was the government ordering all schools to have the children outside for a minimum of 80 minutes every day.<ref name=":3" />

== Society and culture ==
The terms "myopia" and "myopic" (or the common terms "short-sightedness" or "short-sighted", respectively) have been used [[metaphor]]ically to refer to cognitive thinking and decision making that is narrow in scope or lacking in foresight or in concern for wider interests or for longer-term consequences.<ref>Brooks, David (19 March 2009). [https://www.nytimes.com/2009/03/20/opinion/20brooks.html Perverse Cosmic Myopia] {{webarchive|url=https://web.archive.org/web/20151107021551/http://www.nytimes.com/2009/03/20/opinion/20brooks.html |date=7 November 2015 }}. ''New York Times''.</ref> It is often used to describe a decision that may be beneficial in the present, but detrimental in the future, or a viewpoint that fails to consider anything outside a very narrow and limited range. [[Hyperopia]], the biological opposite of myopia, may also be used metaphorically for a [[value system]] or [[motivation]] that exhibits "farsighted" or possibly [[visionary]] thinking and behavior; that is, emphasizing long-term interests at the apparent expense of near-term benefit.<ref>{{cite news |magazine= Wired |url= https://www.wired.com/culture/lifestyle/magazine/17-08/by_work |access-date= 14 August 2009 | vauthors = Thompson C |volume= 17 |number= 8 |date= 17 September 2009 |title= Don't Work All the Time |url-status=live |archive-url= https://web.archive.org/web/20090817183257/http://www.wired.com/culture/lifestyle/magazine/17-08/by_work |archive-date= 17 August 2009 |df= dmy-all }}</ref>

Keeping children indoors, whether to promote early academic activities, because urban development choices leave no place for children to play outside, or because people avoid sunlight because of [[Discrimination based on skin color|a preference for lighter skin color]], causes myopia.<ref name=":2" />  [[Taiwan]] has developed an aggressive program to identify pre-school-age children with pre-myopia and treat them with [[atropine]], and to have schools send students outdoors every day.<ref name=":2" />  The ''Tian-tian 120'' program ("Every day 120") encourages 120 minutes of outdoor time each day.<ref name=":2" />  Compared to the cost of lifelong treatment for myopia with glasses, and in some cases, preventable blindness, the US$13 spent on screening young children for pre-myopia is considered a good investment in [[public health]].<ref name=":2" />

Because myopia can be mitigated through lifestyle choices, it is possible that being myopic will become a marker of an impoverished or neglected childhood, with wealthy families ensuring that their children spend enough time outdoors to prevent or at least reduce it, and poor families, who rely on lower-quality childcare arrangements or not having access to a safe outdoor space, being unable to provide the same benefits to their children.<ref name=":2" />

===Correlations===
Numerous studies have found correlations between myopia, on the one hand, and intelligence and academic achievement, on the other;<ref>{{cite journal | vauthors = Williams KM, Hysi PG, Yonova-Doing E, Mahroo OA, Snieder H, Hammond CJ | title = Phenotypic and genotypic correlation between myopia and intelligence | journal = Scientific Reports | volume = 7 | issue = 1 | pages = 45977 | date = April 2017 | pmid = 28383074 | pmc = 5382686 | doi = 10.1038/srep45977 | bibcode = 2017NatSR...745977W }}</ref> it is not clear whether there is a [[Correlation does not imply causation|causal relationship]].<ref name="IQ2015rev">{{cite journal | vauthors = Verma A, Verma A | title = A novel review of the evidence linking myopia and high intelligence | journal = Journal of Ophthalmology | volume = 2015 | pages = 271746 | year = 2015 | pmid = 25653868 | pmc = 4306218 | doi = 10.1155/2015/271746 | doi-access = free }}</ref> Myopia is also correlated with increased [[microsaccade]] amplitude, suggesting that blurred vision from myopia might cause instability in [[fixational eye movements]].<ref>{{cite journal | vauthors = Ghasia FF, Shaikh AG | title = Uncorrected Myopic Refractive Error Increases Microsaccade Amplitude | journal = Investigative Ophthalmology & Visual Science | volume = 56 | issue = 4 | pages = 2531–5 | date = April 2015 | pmid = 25678690 | doi = 10.1167/iovs.14-15882 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Alexander RG, Macknik SL, Martinez-Conde S | title = Microsaccade Characteristics in Neurological and Ophthalmic Disease | journal = Frontiers in Neurology | volume = 9 | pages = 144 | year = 2018 | pmid = 29593642 | pmc = 5859063 | doi = 10.3389/fneur.2018.00144 | doi-access = free }}</ref>

==Etymology==
The term ''myopia'' is of [[Koine Greek]] origin: {{lang|grc|μυωπία}} {{transliteration|grc|myōpia}} {{gloss|short-sight}} and {{lang|grc|μυωπίασις}} ({{transliteration|grc|myōpiasis}}) {{gloss|short-sight-ness}}. It is derived from the [[ancient Greek]] {{lang|grc|μύωψ}} ({{transliteration|grc|myōps}}) {{gloss|short-sighted}} (man), from {{lang|grc|μύειν}} ({{transliteration|grc|myein}}) {{gloss|to shut the eyes}} and {{lang|grc|ὤψ}} ({{transliteration|grc|ōps}}) {{gloss|eye, look, sight}} (<small>[[Genitive|GEN]]</small> {{lang|grc|ὠπός}} ({{transliteration|grc|ōpos}})).<ref>{{LSJ|muwpi/a|μυωπία}}, {{LSJ|muwpi/asis|μυωπίασις}}, {{LSJ|mu/wy|μύωψ}}, {{LSJ|mu/w|μύειν}}, {{LSJ|w)/y|ὤψ|ref}}.</ref><ref>{{cite book|title=Etymological Dictionary of Greek|others=With the assistance of Lucien van Beek| vauthors = Robert B |author-link=Robert S. P. Beekes|pages=988–9|year=2010|location=Leiden, Boston |publisher=Brill |isbn=9789004174184 |volume=2|series=Leiden Indo-European Etymological Dictionary Series}}</ref><ref>{{cite web|url=http://www.greek-language.gr/greekLang/modern_greek/tools/lexica/triantafyllides/search.html?lq=%CE%BC%CF%85%CF%89%CF%80%CE%AF%CE%B1&dq=|language=el|title=μυωπία|website=Dictionary of Standard Modern Greek. Institute for Modern Greek Studies of the Artistotle University of Thessaloniki|access-date=19 February 2016}}</ref><ref>{{OED2|myopia}}</ref><ref>{{OEtymD|myopia}}</ref> The opposite of ''myopia'' in English is ''hypermetropia'', or [[far-sightedness]].<ref>{{Cite web |last=WebMD |first=Editorial |title=Hyperopia (Farsightedness) |url=https://www.webmd.com/eye-health/farsightedness |access-date=2023-10-25 |website=WebMD |language=en}}</ref>

== See also ==
* [[Myopia in animals]]
* [[Myopic crescent]]
* [[Instrument myopia]]

== References ==
{{reflist|colwidth=30em}}

{{Medical resources
| DiseasesDB = 8729
| ICD10 = {{ICD10|H|52|1|h|49}}
| ICD9 = {{ICD9|367.1}}
| ICDO =
| OMIM =
| MedlinePlus = 001023
| eMedicineSubj =
| eMedicineTopic =
| MeshID = D009216
}}
{{Eye pathology}}
{{Authority control}}
{{Portal bar|Medicine}}

[[Category:Disorders of ocular muscles, binocular movement, accommodation and refraction]]
[[Category:Vision]]
[[Category:Wikipedia medicine articles ready to translate]]
[[Category:Wikipedia neurology articles ready to translate]]
[[Category:Disability]]