Myopia

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 blurred. 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. Myopic individuals have larger pupils than far-sighted (hypermetropic) and emmetropic individuals, likely due to requiring less accommodation (which results in pupil constriction). ==Causes==

The underlying cause of myopia is believed to be a combination of genetic and environmental factors. Risk factors include doing work that involves focusing on close objects, greater time spent indoors, urbanization, and a family history of the condition. It is also associated with a high socioeconomic class and higher level of education. Twin studies indicate that at least some genetic factors are involved. Myopia has been increasing rapidly throughout the developed world, suggesting environmental factors are involved. The role of corrective lenses interfering with emmetropization has also been suggested. Genetics A risk for myopia may be inherited from one's parents. Genetic linkage studies have identified 18 possible locations (loci) on 15 different chromosomes 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. 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. 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. Human population studies suggest that contribution of genetic factors accounts for 60–90% of variance in refraction. 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. Environmental factors Environmental factors that increase the risk of myopia include insufficient light exposure, low physical activity, near work, and increased years of education. Modern humans who spend most of their time indoors, in dimly or fluorescently lit buildings may be at risk of development of myopia. Myopia can be induced with minus spherical lenses, and overminus in prescription lenses can induce myopia progression. Overminus during refraction can be avoided through various techniques and tests, such as fogging, plus to blur, and the duochrome test. 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. ==Mechanism==

Because myopia is a refractive error, the physical cause of myopia is comparable to any optical system that is out of focus. Borish and Duke-Elder classified myopia by these physical causes: • Axial myopia is attributed to an increase in the eye's axial length. • Refractive myopia is attributed to the condition of the refractive elements of the eye. • Index myopia is attributed to variation in the index of refraction of one or more of the ocular media. Under rare conditions, edema of the ciliary body can cause an anterior displacement of the lens, inducing a myopia shift in refractive error. ==Diagnosis==

A diagnosis of myopia is typically made by an eye care professional, usually an optometrist or ophthalmologist. This is by refracting the eye with the use of cycloplegics such as atropine with responses recorded when accommodation is relaxed. • Simple myopia: Myopia in an otherwise normal eye, typically less than 4.00 to 6.00 diopters. This is the most common form of myopia. • Degenerative myopia, also known as malignant, pathological, or progressive myopia, is characterized by marked fundus changes, such as posterior staphyloma, and associated with a high refractive error and subnormal visual acuity after correction. • Pseudomyopia is the blurring of distance vision brought about by spasm of the accommodation system. • Nocturnal myopia: Without adequate stimulus for accurate accommodation, the accommodation system partially engages, pushing distance objects out of focus. Some authors argue for a link between NITM and the development of permanent myopia. • Instrument myopia: over-accommodation when looking into an instrument such as a microscope. Elevation of blood-glucose levels can also cause edema (swelling) of the crystalline lens as a result of sorbitol accumulating in the lens. This edema often causes temporary myopia. Scleral buckles, used in the repair of retinal detachments may induce myopia by increasing the axial length of the eye. • Index myopia is attributed to variation in the index of refraction of one or more of the ocular media. • Form deprivation myopia occurs when the eyesight is deprived by limited illumination and vision range, or the eye is modified with artificial lenses or deprived of clear form vision. 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. Degree The degree of myopia is described in terms of the power of the ideal correction, which is measured in diopters: • 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. • High myopia usually describes myopia of −6.00 or more. People with high myopia are more likely to have retinal detachments and primary open angle glaucoma. They are also more likely to experience floaters, shadow-like shapes which appear in the field of vision. In addition to this, high myopia is linked to macular degeneration, cataracts, and significant visual impairment. The highest myopia ever recorded was −108 diopters by a Slovak, Jan Miskovic. Age at onset Myopia is sometimes classified by the age at onset: This form of myopia is attributed to the use of the eyes for close work during the school years. • Adult onset myopia :* Early adult onset myopia occurs between ages 20 and 40. :*Late adult onset myopia occurs after age 40. ==Prevention and control==

Various methods have been employed in an attempt to decrease the progression of myopia, although studies show mixed results. Many myopia treatment studies have a number of design drawbacks: small numbers, lack of adequate control group, and failure to mask examiners from knowledge of treatments used. The best approach is to combine multiple prevention and control methods. 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. Spending time outdoors Some studies have indicated that having children spend time outdoors reduces the incidence of myopia. 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. 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. 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. The American Optometric Association's Clinical Practice Guidelines found evidence of effectiveness of bifocal lenses and recommends it as the method for "myopia control". In December 2025, the United States Food and Drug Administration approved a new type of lens to help nearsightedness in six to 12 year olds, based on data from the manufacturer Essilor showing children experienced a 70% reduction in the progression of their myopia after two years, with a 50% reduction in eye lengthening in the same period. The lenses use 11 concentric rings full of raised dots to refocus the light onto the retina to slow down the stress on the eye. Medication Anti-muscarinic topical medications in children under 18 years of age may slow the worsening of myopia. These treatments include pirenzepine gel, 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. 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. The use of orthoK can also slow down axial lens elongation. ==Treatment==

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. There is no universally accepted method of preventing myopia and proposed methods need additional study to determine their effectiveness. 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). 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. Orthokeratology Orthokeratology or simply Ortho-K is a temporary corneal reshaping process using rigid gas permeable (RGP) contact lenses. 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. Several studies shown that Ortho-K can reduce myopia progression also. Risk factors of using Ortho-K lenses include microbial keratitis, 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. 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. Alternative medicine A number of alternative therapies have been claimed to improve myopia, including vision therapy, "behavioural optometry", various eye exercises and relaxation techniques, and the Bates method. Scientific reviews have concluded that there was "no clear scientific evidence" that eye exercises are effective in treating myopia and as such they "cannot be advocated". ==Epidemiology==

Global refractive errors have been estimated to affect 800 million to 2.3 billion. The incidence of myopia within sampled population often varies with age, country, sex, race, ethnicity, occupation, environment, and other factors. Variability in testing and data collection methods makes comparisons of prevalence and progression difficult. The prevalence of myopia has been reported as high as 70–90% in some Asian countries, 30–40% in Europe and the United States, and 10–20% in Africa. Myopia is less common in African people and associated diaspora. 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. 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. 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. Asia In some parts of Asia, myopia is very common. • South Korea is believed to have the highest prevalence of myopia in the world; up to 93% of people there have myopia. • China's myopia rate is 80% by high school. and up to 80% to 0.5 dpt. • A study of Jordanian adults aged 17 to 40 found more than half (54%) were myopic. • 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%. • Some research suggests the prevalence of myopia in Indian children is less than 15%. • Up to 90% of young people in Taiwan have myopia. Europe • In first-year undergraduate students in the United Kingdom 50% of British whites and 53% of British Asians were myopic. • 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. 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. 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%). 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. 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. 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. Another found nearly 1 in 8 (13%) of the students in the city of Natal were myopic. ==History==

The difference between the near-sighted and far-sighted people was noted already by Aristotle. 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. 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. 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. 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. == Society and culture ==

The terms "myopia" and "myopic" (or the common terms "short-sightedness" or "short-sighted", respectively) have been used metaphorically 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. 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. 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 a preference for lighter skin color, causes myopia. it is not clear whether there is a causal relationship. Myopia is also correlated with increased microsaccade amplitude, suggesting that blurred vision from myopia might cause instability in fixational eye movements. ==Etymology==

The term myopia is of Koine Greek origin: and () . It is derived from the ancient Greek () (man), from () and () ( ()). The opposite of myopia in English is hypermetropia, or far-sightedness. == See also ==