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Encyclopedia > Myopia
For other uses, see Myopia (disambiguation).
Myopia
Classification & external resources
ICD-10 H52.1
ICD-9 367.1
DiseasesDB 8729
MeSH D009216
Normal vision. Courtesy NIH National Eye Institute
The same view with myopia. (Camera lens was adjusted in a way to physically simulate myopia.)
The same view with myopia. (Camera lens was adjusted in a way to physically simulate myopia.)
Compensating for myopia using a corrective lens.
Compensating for myopia using a corrective lens.

Myopia (from Greek: μυωπία myopia "near-sightedness"[1]), also called near- or short-sightedness, is a refractive defect of the eye in which collimated light produces image focus in front of the retina when accommodation is relaxed. The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) is a coding of diseases and signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or diseases, as classified by the World Health Organization (WHO). ... // H00-H59 - Diseases of the eye and adnexa (H00-H06) Disorders of eyelid, lacrimal system and orbit (H00) Hordeolum and chalazion (H000) Hordeolum and other deep inflammation of eyelid (H001) Chalazion (H01) Other inflammation of eyelid (H010) Blepharitis (H011) Noninfectious dermatoses of eyelid (H02) Other disorders of eyelid (H020) Entropion... The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... The Disease Bold textDatabase is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... Image File history File links Uploadwontworktryin325034503509. ... National Institutes of Health Building 50 at NIH Clinical Center - Building 10 The National Institutes of Health (NIH) is an agency of the United States Ministry of Health and Human Services and is the primary agency of the United States government responsible for biomedical and health-related research. ... The National Eye Institute (NEI) is one of the US National Institutes of Health that was established in 1968. ... Image File history File links Fileisnotcorruptedactuallyupload3453405. ... Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Refraction error, also known as refractive error, is an error in the focusing of light by the eye and a frequent reason for reduced visual acuity. ... For other uses, see Eye (disambiguation). ... Collimated light is light whose rays are parallel. ... An image that is partially in focus, but mostly out of focus in varying degrees. ... Human eye cross-sectional view. ... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ...


Those with myopia see nearby objects clearly but distant objects appear blurred. With myopia, the eyeball is too long, or the cornea is too steep, so images are focused in the vitreous inside the eye rather than on the retina at the back of the eye. The opposite defect of myopia is hyperopia or "farsightedness" or "long-sightedness" — this is where the cornea is too flat or the eye is too short. In psychology, visual perception is the ability to interpret visible light information reaching the eyes which is then made available for planning and action. ... An image that is partially in focus, but mostly out of focus in varying degrees. ... The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber, providing most of an eyes optical power [1]. Together with the lens, the cornea refracts light and, as a result, helps the eye to focus. ... Human eye cross-sectional view. ... Hyperopia, also known as hypermetropia or colloquially as farsightedness or longsightedness, is a defect of vision caused by an imperfection in the eye (often when the eyeball is too short or when the lens cannot become round enough), causing inability to focus on near objects, and in extreme cases causing...


Mainstream ophthalmologists and optometrists most commonly correct myopia through the use of corrective lenses, such as glasses or contact lenses. It may also be corrected by refractive surgery, such as LASIK. The corrective lenses have a negative optical power (i.e. are concave) which compensates for the excessive positive diopters of the myopic eye. In some cases, pinhole glasses are used by patients with low-level myopia. These work by reducing the blur circle formed on the retina. Ophthalmology is the branch of medicine which deals with the diseases of the eye and their treatment. ... Optometrists are primary care practitioners for vision and ocular health concerns. ... A bifocal corrective eyeglasses lens A corrective lens is a lens worn on or before the eye, used to treat myopia, hyperopia, astigmatism, and presbyopia. ... A pair of modern glasses Glasses, also called eyeglasses or spectacles are frames, bearing lenses worn in front of the eyes normally for vision correction, eye protection, or for protection from UV rays. ... A pair of contact lenses, positioned with the concave side facing upward. ... Refractive eye surgery is any eye surgery used to improve the refractive state of the eye and decrease dependency on glasses or contact lenses. ... LASIK is the acronym for Laser-Assisted in Situ Keratomileusis, a type of refractive laser eye surgery performed by ophthalmologists for correcting myopia, hyperopia, and astigmatism. ... This article is about the optical device. ... Optical power or dioptric power or refractive power is the degree to which a lens or mirror converges or diverges light. ... Pinhole glasses, also known as stenopeic glasses, are eyeglasses with a series of pinhole-sized perforations filling an opaque sheet of plastic in place of each lens. ...

Contents

Classification

Myopia has been classified in various manners.[2][3][4]


Etiology

Borish and Duke-Elder classified myopia by cause:[3][4]

  • Axial myopia is attributed to an increase in the eye's axial length.[5]
  • Refractive myopia is attributed to the condition of the refractive elements of the eye.[5] Borish further subclassified refractive myopia:[3]
  • Curvature myopia is attributed to excessive, or increased, curvature of one or more of the refractive surfaces of the eye, especially the cornea.[5] In those with Cohen syndrome, myopia appears to result from high corneal and lenticular power.[6]
  • Index myopia is attributed to variation in the index of refraction of one or more of the ocular media.[5]

This article or section does not cite its references or sources. ... The refractive index of a material is the factor by which electromagnetic radiation is slowed down (relative to vacuum) when it travels inside the material. ...

Clinical entity

Various forms of myopia have been described by their clinical appearance:[4][7]

  • Simple myopia is more common than other types of myopia and is characterized by an eye that is too long for its optical power (which is determined by the cornea and crystalline lens) or optically too powerful for its axial length.[8] Both genetic and environmental factors, particularly significant amounts of near work, are thought to contribute to the development of simple myopia.[8]
  • 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.[5] This form of myopia gets progressively worse over time. Degenerative myopia has been reported as one of the main causes of visual impairment.[9] Myopia with degenerative changes has been described as being very common in certain races and cultures, such as Chinese, Japanese, Korean, Arab, and Jewish people.[10]
  • Nocturnal myopia, also known as night myopia or twilight myopia, is a condition in which the eye has a greater difficulty seeing in low illumination areas, even though its daytime vision is normal. Essentially, the eye's far point of an individual's focus varies with the level of light. Night myopia is believed to be caused by pupils dilating to let more light in, which adds aberrations resulting in becoming more nearsighted. A stronger prescription for myopic night drivers is often needed. Younger people are more likely to be affected by night myopia than the elderly.[11]
  • Pseudomyopia is the blurring of distance vision brought about by spasm of the ciliary muscle.[12]
  • Induced myopia, also known as acquired myopia, results from exposure to various pharmaceuticals, increases in glucose levels, nuclear sclerosis, or other anomalous conditions.[8] The encircling bands used in the repair of retinal detachments may induce myopia by increasing the axial length of the eye.[13]
  • Index myopia is attributed to variation in the index of refraction of one or more of the ocular media.[5] Cataracts may lead to index myopia.[14]
  • Form deprivation myopia is a type of myopia that occurs when the eye is deprived of clear form vision.[15] Myopia is often induced this way in various animal models to study the pathogenesis and mechanism of myopia development.[15]

Optical power or dioptric power or refractive power is the degree to which a lens or mirror converges or diverges light. ... The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber, providing most of an eyes optical power [1]. Together with the lens, the cornea refracts light and, as a result, helps the eye to focus. ... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ... Visual impairment is the functional loss of vision. ... Pseudomyopia refers to an intermittent and temporary shift in refraction of the eye towards myopia. ... The ciliary muscle is a smooth muscle of the head that is responsible for accommodation of the eye // The ciliary muscle affects zonular fibers in the eye (fibers that suspend the lens in position during accommodation), enabling changes in lens shape for light focusing. ... Pharmacology (in Greek: pharmacon is drug, and logos is science) is the study of how chemical substances interfere with living systems. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... Nuclear sclerosis Nuclear sclerosis, also known as lenticular sclerosis, is a normal progressive change of the lens in older dogs. ...

Degree

Myopia, which is measured in diopters by the strength or optical power of a corrective lens that focuses distant images on the retina, has also been classified by degree or severity:[2] A dioptre (also diopter) is a unit of curvature equal to one per metre; that is, inverse metres, or 1/(metres). ... Optical power or dioptric power or refractive power is the degree to which a lens or mirror converges or diverges light. ...

Pigment Dispersion Syndrome (PDS) is an affliction of the eye that, if left untreated, can lead a form of glaucoma known as pigmentary glaucoma. ... Human eye cross-sectional view. ... Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. ... Human eye cross-sectional view. ... For other uses, see Floater (disambiguation). ... The term visual field is sometimes used as a synonym to field of view, though they do not designate the same thing. ...

Age of onset

Myopia is sometimes classified by the age of onset:[2]

  • Congenital myopia, also known as infantile myopia, is present at birth and persists through infancy.[8]
  • Youth onset myopia occurs prior to age 20.[8]
  • School myopia appears during childhood, particularly the school-age years.[19] This form of myopia is attributed to the use of the eyes for close work during the school years.[5]
  • Adult onset myopia
  • Early adult onset myopia occurs between ages 20 and 40.[8]
  • Late adult onset myopia occurs after age 40.[8]

Epidemiology

The global prevalence of refractive errors has been estimated from 800 million to 2.3 billion.[20] The incidence of myopia within sampled population often varies with age, country, sex, race, ethnicity, occupation, environment, and other factors.[10][21] Variability in testing and data collection methods makes comparisons of prevalence and progression difficult.[22] Look up age in Wiktionary, the free dictionary. ... This article or section does not cite its references or sources. ... For other uses, see Race. ... This article or section should be merged with ethnic group Ethnicity is the cultural characteristics that connect a particular group or groups of people to each other. ...


In some areas, such as Japan, Singapore and Taiwan, up to 44% of the adult population is myopic.[citation needed]


A recent study involving first-year undergraduate students in the United Kingdom found that 50% of British whites and 53.4% of British Asians were myopic.[23]


In Australia, the overall prevalence of myopia (worse than −0.50 diopters) has been estimated to be 77%.[24] In one recent study, less than 1 in 10 (8.4%) Australian children between the ages of 4 and 12 were found to have myopia greater than −0.50 diopters.[25] A recent review found that 16.4% of Australians aged 40 or over have at least −1.00 diopters of myopia and 2.5% have at least −5.00 diopters.[26]


In Brazil, a 2005 study estimated that 6.4% of Brazilians between the ages of 12 and 59 had −1.00 diopter or myopia or more, compared with 2.7% of the indigenous people in northwestern Brazil.[27] Another found nearly 1 in 8 (13.3%) of the students in one city were myopic.[28]


In Greece, the prevalence of myopia among 15 to 18 year old students was found to be 36.8%.[29]


In India, the prevalence of myopia in the general population has been reported to be only 6.9%.[30][29]


A recent review found that 26.6% of Western Europeans aged 40 or over have at least −1.00 diopters of myopia and 4.6% have at least −5.00 diopters.[31]


In the United States, the prevalence of myopia has been estimated at 20%.[10] Nearly 1 in 10 (9.2%) American children between the ages of 5 and 17 have myopia.[32] Approximately 25% of Americans between the ages of 12 and 54 have the condition.[33] A recent review found that 25.4% of Americans aged 40 or over have at least −1.00 diopters of myopia and 4.5% have at least −5.00 diopters.[34]


A study of Jordanian adults aged 17 to 40 found that over half (53.7%) were myopic.[35]


Ethnicity and race

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.[21] For other uses, see Asia (disambiguation). ...


Myopia is less common in black and African people.[10] In Americans between the ages of 12 and 54, myopia has been found to affect whites less than blacks[33]. Asians had the highest prevalence (78.5%), followed by Hispanics (13.2%). Whites had the lowest prevalence of myopia (4.4%), which was not significantly different from African Americans (6.6%). For hyperopia, whites had the highest prevalence (19.3%), followed by Hispanics (12.7%). Asians had the lowest prevalence of hyperopia (6.3%) and were not significantly different from African Americans (6.4%). For astigmatism, Asians and Hispanics had the highest prevalences (33.6% and 36.9%, respectively) and did not differ from each other (P = .17). African Americans had the lowest prevalence of astigmatism (20.0%), followed by whites (26.4%).[36] Though most indigenous Africans possess relatively dark skin, they exhibit much variation in physical appearance. ... World map showing location of Africa A satellite composite image of Africa Africa is the worlds second_largest continent in both area and population, after Asia. ... In optics, astigmatism (from Greek: α- a- without + στίγματος stigmatos, gen. ... In statistical hypothesis testing, the p-value of a random variable T used as a test statistic is the probability that T will assume a value at least as extreme as the observed value tobserved, given that a null hypothesis being considered is true. ...


Education, intelligence, and IQ

A number of studies have shown that the prevalence of myopia increases with level of education[33][29] and many studies have shown a relationship between myopia and IQ. However, care must be taken in interpreting these results as correlation does not imply causation. IQ redirects here; for other uses of that term, see IQ (disambiguation). ... Correlation does not imply causation is a phrase used in the sciences and statistics to emphasize that correlation between two variables does not imply there is a cause-and-effect relationship between the two. ...


According to Arthur Jensen, myopes average 7-8 IQ points higher than non-myopes. The relationship also holds within families, and siblings with a higher degree of refraction error average higher IQs than siblings with less refraction error. Jensen believes that this indicates myopia and IQ are pleiotropically related as they are caused or influenced by the same genes. No mechanism that could cause a relationship between myopia and IQ has yet been identified. For the Danish actor, see Arthur Jensen (actor). ... Refraction error is an error in the focussing of light by the human eye. ... Pleiotropy occurs when a single gene influences multiple phenotypic traits. ...


Etiology and pathogenesis

Because in the most common, "simple" myopia, the eye length is too long, any etiologic explanation must account for such axial elongation. To date, no single theory has been able to satisfactorily explain this elongation. Etiology (alternately aetiology, aitiology) is the study of causation. ... The word theory has a number of distinct meanings in different fields of knowledge, depending on their methodologies and the context of discussion. ...


In the early 1900s, William Bates controversially asserted that myopia, as with all refractive errors, resulted from a particular type of "eyestrain" that was itself a result of "mental strain".[37] He stated that the shape of the eyeball responded instantaneously to the action of the extraocular muscles upon it[38] and that myopia was produced due to contraction of the inferior oblique and superior oblique muscles which lengthened the eye.[39] According to Bates, myopia was associated with a "strain" to see distance objects rather than near work.[40] Bates theories were rejected by mainstream ophthalmologists of his time and remain so today.[41][42] William Horatio Bates (December 23, 1860 - July 10, 1931) was an American physician and ophthalmologist who developed what is now known as the Bates Method of natural vision improvement [1], a collection of techniques and exercises intended to improve vision. ... The extraocular muscles are the six muscles that control the movements of the eye. ... The inferior oblique muscle is a muscle in the orbit that adducts (medially rotates) and elevates the eyeball. ... The superior oblique muscle is a muscle in the orbit that causes the eye to look downwards when it is already directed medially (looking towards the nose). ...


In the mid-1900s, mainstream ophthalmologists and optometrists believed myopia to be primarily hereditary; the influence of near work in its development seemed "incidental" and the increased prevalence of the condition with increasing age was viewed as a "statistical curiosity".[3][4][43]


Among mainstream researchers and eye care professionals, myopia is now thought to be a combination of genetic and environmental factors.[8][19] An eye care professional is an individual who provides a service related to the eyes or vision. ...


There are currently two basic mechanisms believed to cause myopia: form deprivation (also known as pattern deprivation[44]) and optical defocus.[45] Form deprivation occurs when the image quality on the retina is reduced; optical defocus occurs when light focuses in front of or behind the retina. Numerous experiments with animals have shown that myopia can be artificially generated by inducing either of these conditions. In animal models wearing negative spectacle lenses, axial myopia has been shown to occur as the eye elongates to compensate for optical defocus.[45] The exact mechanism of this image-controlled elongation of the eye is still unknown.[citation needed] It has been suggested that accommodative lag leads to blur (i.e. optical defocus) which in turn stimulates axial elongation and myopia.[46] In optics, defocus is the one aberration familiar to nearly everyone who has ever needed eyeglasses or used a camera, videocamera, microscope, telescope, or binoculars, as it simply means out of focus. ... Human eye cross-sectional view. ...


Theories

  • Combination of genetic and environmental factors — In China, myopia is more common in those with higher education background[47] and some studies suggest that near work may exacerbate a genetic predisposition to develop myopia.[48] Other studies have shown that near work (reading, computer games) may not be associated with myopic progression, however.[49] A "genetic susceptibility" to environmental factors has been postulated as one explanation for the varying degrees of myopia among individuals or populations,[50] but there exists some difference of opinion as to whether it exists.[19][51] High heritability simply means that most of the variation in a particular population at a particular time is due to genetic differences. If the environment changes — as, for example, it has by the introduction of televisions and computers — the incidence of myopia can change as a result, even though heritability remains high. From a slightly different point of view it could be concluded that — determined by heritage — some people are at a higher risk to develop myopia when exposed to modern environmental conditions with a lot of extensive near work like reading. In other words, it is often not the myopia itself which is inherited, but the reaction to specific environmental conditions — and this reaction can be the onset and the progression of myopia.
  • Genetic factors — The wide variability of the prevalence of myopia in different ethnic groups has been reported as additional evidence supporting the role of genetics in the development of myopia.[52] Measures of the heritability of myopia have yielded figures as high as 89%, and recent research has identified genes that may be responsible: defective versions of the PAX6 gene seem to be associated with myopia in twin studies [1]. Under this theory, the eye is slightly elongated front to back as a result of faults during development, causing images to be focused in front of the retina rather than directly on it. It is usually discovered during the pre-teen years between eight and twelve years of age. It most often worsens gradually as the eye grows during adolescence and then levels off as a person reaches adulthood. Genetic factors can work in various biochemical ways to cause myopia, a weak or degraded connective tissue is a very essential one. Genetic factors include an inherited, increased susceptibility for environmental influences like excessive near work, and the fact that some people do not develop myopia in spite of very adverse conditions is a clear indication that heredity is involved somehow in any case.
  • Environmental factors — It has been suggested that a genetic susceptibility to myopia does not exist.[19] A high heritability of myopia (as for any other condition) does not mean that environmental factors and lifestyle have no effect on the development of the condition. Some recommend a variety of eye exercises to strengthen the ciliary muscle. Other theories suggest that the eyes become strained by the constant extra work involved in "nearwork" and get stuck in the near position, and eye exercises can help loosen the muscles up thereby freeing it for far vision. These primarily mechanical models appear to be in contrast to research results, which show that the myopic elongation of the eye can be caused by the image quality, with biochemical processes as the actuator. Common to both views is, however, that extensive near work and corresponding accommodation can be essential for the onset and the progression of myopia.
One Austrian study confirmed that the axial length of the eye does mildly increase while reading, but attributed this elongation due to contraction of the ciliary muscle during accommodation (the process by which the eye increases optical power to maintain a clear image focus), not "squeezing" of the extraocular muscles.[53]
Near work and nightlight exposure in childhood have been hypothesized as environmental risk factors for myopia.[54] Although one initial study indicated a strong association between myopia and nightlight exposure,[55] recent research has found none.[54][56][57][58]
  • Near work. Near work has been implicated as a contributing factor to myopia in some studies, but refuted in others.[59] One recent study suggested that students exposed to extensive "near work" may be at a higher risk of developing myopia, whereas extended breaks from near work during summer or winter vacations may retard myopic progression [2]. Near work in certain cultures (e.g. Vanuatu) does not result in greater myopia[3][4][5][6]. It has been hypothesized that this outcome may be a results of genetics or environmental factors such as diet or over-illumination, changes in which seem to occur in Asian, Vanuatu and Inuit cultures acclamating to intensive early studies[7].
  • Diet and nutrition - One 2002 article suggested that myopia may be caused by over-consumption of bread in childhood, or in general by diets too rich in carbohydrates, which can lead to chronic hyperinsulinemia. Various other components of the diet, however, were made responsible for contributing to myopia as well, as summarized in a documentation.
  • Stress has been postulated as a factor in the development of myopia.[60]

In genetics, heritability is the proportion of phenotypic variation in a population that is attributable to genetic variation among individuals. ... For other uses, see Gene (disambiguation). ... // Introduction Paired box (Pax) genes are a family of tissue specific transcription factors containing a PAIRED domain and usually a partial or complete homeodomain. ... Twin study - Wikipedia /**/ @import /skins-1. ... An image that is partially in focus, but mostly out of focus in varying degrees. ... Human eye cross-sectional view. ... Teen redirects here. ... Connective tissue is one of the four types of tissue in traditional classifications (the others being epithelial, muscle, and nervous tissue. ... The Bates method of natural vision improvement is a program created by ophthalmologist William Horatio Bates, M.D., which aims to correct what Bates, and teachers of the Bates method, see as faulty vision habits through relaxation techniques, exercises and optional activities and games. ... The ciliary muscle is a smooth muscle of the head that is responsible for accommodation of the eye // The ciliary muscle affects zonular fibers in the eye (fibers that suspend the lens in position during accommodation), enabling changes in lens shape for light focusing. ... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ... This cosmetics store has lighting levels over twice recommended levels and sufficient to trigger headaches and other health effects Over-illumination is the presence of lighting intensity (illuminance) beyond that required for a specified activity. ... Carbohydrates (literally hydrates of carbon) are chemical compounds that act as the primary biological means of storing or consuming energy, other forms being fat and protein. ... Hyperinsulinemia, present in people with Diabetes mellitus type 2 or insulin resistance where excess levels of circulating insulin in blood. ...

Relevant research

  • A Turkish study found that accommodative convergence, rather than accommodation, may be a factor in the onset and progression of myopia in adults.[61]
  • A recent Polish study revealed that "with-the-rule astigmatism" may lead to the creation of myopia.[62]

Accommodative convergence is that portion of the range of inward rotation of both eyes (i. ...

Presbyopia and the 'payoff' for the nearsighted

Many people with myopia are able to read comfortably without eyeglasses even in advanced age. Myopes considering refractive surgery are advised that this may be a disadvantage after the age of 40 when the eyes become presbyopic and lose their ability to accommodate or change focus. Refractive eye surgery is any eye surgery used to improve the refractive state of the eye and decrease dependency on glasses or contact lenses. ... Presbyopia (Greek word presbyteros (πρεσβύτερος), meaning elder) is the eyes diminished ability to focus that occurs with aging. ... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ...


Diagnosis

A diagnosis of myopia is typically confirmed during an eye examination by an ophthalmologist or an optometrist. Frequently an autorefractor or retinoscope is used to give an initial objective assessment of the refractive status of each eye, then a phoropter is used to subjectively refine the patient's eyeglass prescription. Traditional Snellen chart used for visual acuity testing. ... Ophthalmology is the branch of medicine which deals with the diseases of the eye and their treatment. ... Optometrists are primary care practitioners for vision and ocular health concerns. ... An automated refractor, or autorefractor, is a computer-controlled machine used during an eye examination to provide an objective measurement of a persons refractive error and prescription for glasses or contact lenses. ... Retinoscopy is a technique to obtain an objective measurement of the refractive condition of a patients eye. ... A refractor in use The name and shape of the PHOROPTOR® is a registered trademark of Reichert, Inc. ... Using a phoropter to determine a prescription for eyeglasses An eyeglass prescription is a written order by an ophthalmologist or an optometrist to an optician for eyeglasses. ...


Treatment, management, and prevention

Glasses are commonly used to address short-sightedness.
Glasses are commonly used to address short-sightedness.

Eyeglasses, contact lenses, and refractive surgery are the primary options to treat the visual symptoms of those with myopia. Orthokeratology is the practice of using special rigid contact lenses to flatten the cornea to reduce myopia. Image File history File linksMetadata No higher resolution available. ... Image File history File linksMetadata No higher resolution available. ... Glasses, spectacles, or eyeglasses are frames bearing lenses worn in front of the eyes, sometimes for purely aesthetic reasons but normally for vision correction or eye protection. ... A soft contact lens A contact lens (also known as contact, for short) is a corrective or cosmetic lens placed on the cornea of the eye atop the iris. ... Refractive eye surgery is any eye surgery used to improve the refractive state of the eye and decrease dependency on glasses or contact lenses. ... Orthokeratology (Ortho-K) is the use of rigid gas-permeable contact lenses, normally worn only at night, to improve vision through the reshaping of the cornea. ...


Eye-exercises and biofeedback

Practitioners and advocates of alternative therapies often recommend eye exercises and relaxation techniques such as the Bates method. However, the efficacy of these practices is disputed by scientists and eye care practitioners.[41] A 2005 review of scientific papers on the subject concluded that there was "no clear scientific evidence" that eye exercises were effective in treating myopia.[42] Alternative medicine has been described as any of various systems of healing or treating disease (as chiropractic, homeopathy, or faith healing) not included in the traditional medical curricula taught in the United States and Britain.[1] Alternative medicine practices are often based in belief systems not derived from modern science. ... The Bates method of natural vision improvement is a program created by ophthalmologist William Horatio Bates, M.D., which aims to correct what Bates, and teachers of the Bates method, see as faulty vision habits through relaxation techniques, exercises and optional activities and games. ...


In the eighties and nineties, there was a flurry of interest in biofeedback as a possible treatment for myopia. A 1997 review of this biofeedback research concluded that "controlled studies to validate such methods ... have been rare and contradictory."[63] It was found in one study that myopes could improve their visual acuity with biofeedback training, but that this improvement was "instrument-specific" and did not generalise to other measures or situations.[64] In another study an "improvement" in visual acuity was found but the authors concluded that this could be a result of subjects learning the task.[65] Finally, in an evaluation of a training system designed to improve acuity, "no significant difference was found between the control and experimental subjects".[66] Biofeedback mechanism. ...


The eye exercises include 1] Blinking of eyes 2] Focussing of eyes 3] Shifting from distant to near point of eyes 4] Washing the eyes 5] Bhramari pranayam 5] bhrumadhya drishti 6] nasikagra drishti and 7] upward/downward, rotatory, side to side and diagonal movements of eyes. There are some more modifications in these also.[Cf. Tejaswi drishti: E - Book: Dr. Shriniwas kashalikar].


Prevention

There is no universally accepted method of preventing myopia.[8] Some clinicians and researchers recommend plus power (convex) lenses in the form of single vision reading lenses or bifocals.[8][67] A recent Malaysian study reported in New Scientist[68] suggested that undercorrection of myopia caused more rapid progression of myopia,[69] However, the reliability of this data has been called into question.[70] Many myopia treatment studies suffer from any of a number of design drawbacks: small numbers, lack of adequate control group, failure to mask examiners from knowledge of treatments used, etc. Bifocals are eyeglasses that have corrective lenses containing two different lens powers. ... New Scientist is a weekly international science magazine covering recent developments in science and technology for a general English-speaking audience. ... The sample size of a statistical sample is the number of repeated measurements that constitute it. ... A scientific control augments integrity in experiments by isolating variables as dictated by the scientific method in order to make a conclusion about such variables. ... For the communication paradox, see double bind. ...


Pirenzepine eyedrops had a limited effect on retarding myopic progression in a recent, placebo-control, double-blinded prospective controlled study.[71] This does not cite any references or sources. ... A Study design is a way to set up an epidemiological investigation, as a form of clinical trial. ...


Myopia control

Various methods have been employed in an attempt to decrease the progression of myopia.[45] Altering the use of eyeglasses between full-time, part-time, and not at all does not appear to alter myopia progression.[72][73] Bifocal and progressive lenses have not shown significant differences in altering the progression of myopia.[45] Progressive lenses, also called progressive addition lenses (PAL), progressive power lenses, graduated lenses and varifocal lenses, are corrective lenses used in eyeglasses to correct presbyopia and other disorders of accommodation. ...


Myopia as metaphor

The terms myopia and myopic (or the common terms short sightedness or short sighted) have also been used metaphorically to refer to cognitive thinking and decision making that is narrow sighted or lacking in concern for wider interests or longer-term consequences. This article is about metaphor in literature and rhetoric. ...


See for example: Marketing myopia. Marketing myopia is a term used in marketing. ...


See also

Astigmatism is an affliction of the eye, where vision is blurred by an irregularly shaped cornea. ... Hyperopia, also known as hypermetropia or colloquially as farsightedness or longsightedness, is a defect of vision caused by an imperfection in the eye (often when the eyeball is too short or when the lens cannot become round enough), causing inability to focus on near objects, and in extreme cases causing... An optician is an individual who makes and adjusts optical aids. ... Evolutionary pressure or selection pressure can be formalized as an external pressure applied to a process, thereby pushing that process in a distinct direction. ...

References

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The Online Computer Library Center (OCLC) was founded in 1967 and originally named the Ohio College Library Center. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... is the 239th day of the year (240th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...

External links

v • d • e
Pathology of the eye (primarily H00-H59, 360-379)
Eyelid, lacrimal system and orbit eyelid: inflammation (Stye, Chalazion, Blepharitis) - Entropion - Ectropion - Lagophthalmos - Blepharochalasis - Ptosis - Blepharophimosis - Xanthelasma - Trichiasis

lacrimal system: Dacryoadenitis - Epiphora - Dacryocystitis A renal cell carcinoma (chromophobe type) viewed on a hematoxylin & eosin stained slide Pathologist redirects here. ... For other uses, see Eye (disambiguation). ... An eyelid is a thin fold of skin that covers and protects an eye. ... Tears are a liquid produced by the bodys process of lacrimation to clean and lubricate the eyes. ... In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. ... An eyelid is a thin fold of skin that covers and protects an eye. ... A stye (IPA: ) or hordeolum () is an infection of the sebaceous glands at the base of the eyelashes. ... A chalazion, also known as a Meibomian gland lipogranuloma, is a cyst in the eyelid that is caused by inflammation of the meibomian gland, usually on the upper eyelid. ... Blepharitis is inflammation of the eyelids. ... Entropion is a medical condition in which the eyelids fold inward. ... Ectropion is a condition of loose eyelids. ... Lagophthalmos describes difficulty in complete closure of the eyelid over the eyeball. ... Blepharochalasis is an inflammation of the eyelid that is characterized by exacerbations and remissions of eyelid edema, which results in a stretching and subsequent atrophy of the eyelid tissue. ... In ophthalmology, ptosis is an abnormally low position (drooping) of the upper eyelid which may grow more or less severe during the day. ... Xanthelasma (or xanthelasma palpebrarum) are sharply demarcated yellowish collections of cholesterol underneath the skin, usually around the eyes. ... Trichiasis is a medical term for ingrown eyelashes. ... Tears are a liquid produced by the bodys process of lacrimation to clean and lubricate the eyes. ... Dacryoadenitis is inflammation of the lacrimal glands (the tear-producing glands). ... Epiphora is excessive tear production, usually a result from an irritation of the eye. ... Dacryocystitis is an infection of the nasolacrimal sac. ...

orbit: Exophthalmos - Enophthalmos
Conjunctiva Conjunctivitis - Pterygium - Pinguecula - Subconjunctival hemorrhage
Sclera and cornea Scleritis - Keratitis - Corneal ulcer - Snow blindness - Thygeson's superficial punctate keratopathy - Fuchs' dystrophy - Keratoconus - Keratoconjunctivitis sicca - Arc eye - Keratoconjunctivitis - Corneal neovascularization - Kayser-Fleischer ring - Arcus senilis - Band keratopathy
Iris and ciliary body Iritis - Uveitis - Iridocyclitis - Hyphema - Persistent pupillary membrane - Iridodialysis - Synechia
Lens Cataract - Aphakia - Ectopia lentis
Choroid and retina Retinitis - Chorioretinitis - Choroideremia - Retinal detachment - Retinoschisis - Retinopathy (Bietti's crystalline dystrophy, Coats disease, Diabetic retinopathy, Hypertensive retinopathy, Retinopathy of prematurity) - Macular degeneration - Retinitis pigmentosa - Retinal haemorrhage - Central serous retinopathy - Macular edema - Epiretinal membrane - Macular pucker - Vitelliform macular dystrophy
Optic nerve and visual pathways Optic neuritis - Papilledema - Optic atrophy - Leber's hereditary optic neuropathy
Ocular muscles,
binocular movement,
accommodation and refraction		 Paralytic strabismus: Ophthalmoparesis - Progressive external ophthalmoplegia - Palsy (III, IV, VI) - Kearns-Sayre syndrome

Other strabismus: Esotropia/Exotropia - Hypertropia - Heterophoria (Esophoria, Exophoria) - Brown's syndrome - Duane syndrome
Other binocular: Conjugate gaze palsy - Convergence insufficiency - Internuclear ophthalmoplegia - One and a half syndrome
Two bodies with a slight difference in mass orbiting around a common barycenter. ... Exophthalmos (or proptosis) is a bulging of the eye anteriorly out of the orbit. ... Enophthalmos is recession of the eyeball within the orbit. ... Image of a human eye clearly showing the blood vessels of the conjuntiva. ... Pterygium usually refers to a benign growth of the conjunctiva. ... A Pinguecula is a type of conjunctival degeneration in the eye. ... A subconjunctival hemorrhage is a common and relatively minor post-LASIK complication. ... Schematic diagram of the human eye. ... The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber, providing most of an eyes optical power [1]. Together with the lens, the cornea refracts light and, as a result, helps the eye to focus. ... Scleritis is a serious inflammatory disease that affects the white outer coating of the eye, known as the sclera. ... A corneal ulcer is an inflammatory condition of the cornea involving loss of its outer layer. ... For other meanings see Snowblind. ... Thygesons superficial punctate keratopathy (TSPK) is a disease of the eyes. ... Fuchs dystrophy is a slowly progressing corneal disease that usually affects both eyes and is slightly more common in women than in men. ... Keratoconus (from Greek: kerato- horn, cornea; and konos cone), is a degenerative non-inflammatory disorder of the eye in which structural changes within the cornea cause it to thin and change to a more conical shape than its normal gradual curve. ... Keratoconjunctivitis sicca (KCS), also called keratitis sicca,[1] sicca syndrome,[1] xerophthalmia,[1] dry eye syndrome (DES),[1] or simply dry eyes,[1] is an eye disease caused by decreased tear production or increased tear film evaporation commonly found in humans and some animals[2]. Keratoconjunctivitis sicca is Latin and... Arc eye, also known as arc flash, welders flash, corneal flash burns, or flash burns, is a painful ocular condition sometimes experienced by welders who have failed to use adequate eye protection. ... Keratoconjunctivitis sicca or KCS is an eye disease caused by decreased tear production or increased tear film evaporation commonly found in people and small animals. ... Corneal neovascularization is the excessive ingrowth of blood vessels from the limbal vascular plexus into the cornea. ... Kayser-Fleischer rings are pigmented rings in the peripheral cornea, resulting from copper deposition in Descemets membrane. ... Arcus senilis (or Arcus senilis corneae. ... Band keratopathy is a corneal disease derived from the appearance of calcium on the central cornea. ... In anatomy, the iris (plural irises or irides) is the most visible part of the eye of vertebrates, including humans. ... Schematic diagram of the human eye The ciliary body is the part of the eye containing the ciliary muscle and ciliary processes. ... Iritis is a form of anterior uveitis and refers to the inflammation of the iris of the eye. ... Uveitis specifically refers to inflammation of the middle layer of the eye, termed the uvea but in common usage may refer to any inflammatory process involving the interior of the eye. ... Iridocyclitis, also known as anterior uveitis, is a condition in which the uvea of the eye suffers inflammation. ... Caused by a blunt blow to the eye. ... Persistent pupillary membrane (PPM) is a condition of the eye involving remnants of a fetal membrane that persist as strands of tissue crossing the pupil. ... Iridodialysis, sometimes known as a coredialysis, is a localized separation or tearing away of the iris from its attachment to the ciliary body. ... A synechia is an eye condition where the iris adheres to the either the cornea (i. ... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ... Human eye cross-sectional view, showing position of human lens. ... Aphakia is the absence of the lens of the eye, due to surgical removal, perforating wound or ulcer, or congenital anomaly; causes a loss of accommodation, hyperopia, and a deep anterior chamber. ... Anterior lens luxation Ectopia lentis is a displacement or malposition of the eyes crystalline lens from its normal location. ... The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye lying between the retina and the sclera. ... Human eye cross-sectional view. ... The retinitis is defined as the inflammation of the retina. ... In medicine, Chorioretinitis is an inflammation of the choroid and retina of the eye. ... Choroideremia is an X-linked recessive retinal degenerative disease that leads to the degeneration of the choriocapillaris, the retinal pigment epithelium, and the photoreceptor of the eye. ... Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. ... Retinoschisis is an uncommon eye disease characterized by the abnormal splitting of the retinas sensory layers, usually in the outer plexiform layer, with resulting loss of visual function [1]. The retina, which consists of multiple layers of interconnected nerve and pigment cells, separates into separate layers resulting in a... Retinopathy is a general term that refers to some form of non-inflammatory damage to the retina of the eye. ... Coats’ disease, (also known as exudative retinitis or retinal telangiectasis, sometimes spelled Coates disease), is a rare eye disorder, causing full or partial blindness, characterized by abnormal development of blood vessels behind the retina. ... Diabetic retinopathy is retinopathy (damage to the retina) caused by complications of diabetes mellitus, which could eventually lead to blindness. ... Hypertension, or high blood pressure that does not respond to treatment, has several ocular manifestations. ... Retinopathy of prematurity (ROP), previously known as retrolental fibroplasia (RLF), is a disease of the eye that affects prematurely born babies. ... Listen to this article ( info/dl) This audio file was created from an article revision dated 2005-07-19, and may not reflect subsequent edits to the article. ... Normal vision. ... Retinal haemorrhage is a disorder of the eye in which bleeding occurs into the retina. ... Central serous retinopathy or CSR is a visual impairment, often temporary, usually in one eye, affecting males in the age group 20 to 50. ... Macular edema occurs when fluid and protein deposits collect on or under the macula, causing it to thicken and swell. ... Human eye cross-sectional view. ... Human eye cross-sectional view. ... This article is about the anatomical structure. ... The visual system is the part of the nervous system which allows organisms to see. ... Optic neuritis, sometimes called retrobulbar neuritis, is the inflammation of the optic nerve that may cause a complete or partial loss of vision. ... Papilledema is optic disc swelling that is caused by increased intracranial pressure. ... Optic atrophy is a pathological term and somewhat misleading. ... Leber’s hereditary optic neuropathy (LHON) or Leber optic atrophy is a mitochondrially inherited (mother to all offspring) form of acute or subacute loss of central vision that may lead to degeneration of retinal ganglion cells (RGCs) and their axons; this affects predominantly young adult males. ... MRI scan showing lateral and medial rectus muscles. ... Binocular vision is vision in which both eyes are used together. ... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ... For the property of metals, see refraction (metallurgy). ... Ophthalmoparesis is a physical finding in certain neurologic illnesses. ... Progressive external ophthalmoplegia is a disorder of the mitochondria. ... Oculomotor nerve palsy is an eye condition resulting from damage to the third cranial nerve or a branch thereof. ... Fourth nerve palsy is a condition present at birth characterized by a vertical misalignment of the eyes due to a weakness or paralysis of the superior oblique muscle. ... Sixth nerve palsy, or abducens nerve palsy, is a disorder associated with dysfunction of cranial nerve VI (the abducens nerve) which is responsible for contracting the lateral rectus muscle to abduct (i. ... Kearns-Sayre syndrome (abbreviated KSS) is a disease caused by a 5,000 base deletion in the mitochondrial DNA. As such, it is a rare genetic disease in that it can be heteroplasmic, that is, more than one genome can be in a cell at any given time. ... Strabismus (from Greek: στραβισμός strabismos, from στραβίζειν strabizein to squint, from στραβός strabos squinting, squint-eyed[1]) is a condition in which the eyes are not properly aligned with each other. ... Person exhibiting esotropia of the right eye Esotropia is a form of strabismus, or squint, in which one or both eyes turns inward. ... Person exhibiting exotropia of the right eye Exotropia is a form of strabismus where the eyes are deviated outward. ... Hypertropia is a condition of misalignment of the eyes (strabismus), whereby the visual axis of one eye is higher than the fellow fixating eye. ... Heterophoria is a type of eye condition where the motion of the eyes is not parallel to each other. ... Esophoria is characterised by inward deviation of the eye usually due to extra-ocular muscle imbalance. ... This article or section does not cite any references or sources. ... Browns syndrome is due to fibrous adhesions in the upper medial quadrant of the orbit. ... Duane syndrome (DS) is a rare, congenital eye movement disorder most commonly characterized by the inability of the eye to turn out. ... Conjugate gaze palsy refers to an inability of both eyes to move in the same direction at the same time. ... Convergence insufficiency is a sensory and neuromuscular anomaly of the binocular vision system, characterized by an inability to converge the eyes or sustain convergence. ... Internuclear ophthalmoplegia is a physical finding, or sign, that is a particular form of [[[ophthalmoparesis]]. It can affect either the right or left eye. ... Schematic representation of most common extra-ocular movement abnormality in one and a half syndrome. ...

Refractive error: Hyperopia/Myopia - Astigmatism - Anisometropia/Aniseikonia - Presbyopia
Visual disturbances and blindness Amblyopia - Leber's congenital amaurosis - Subjective (Asthenopia, Hemeralopia, Photophobia, Scintillating scotoma) - Diplopia - Scotoma - Anopsia (Binasal hemianopsia, Bitemporal hemianopsia, Homonymous hemianopsia, Quadrantanopia) - Color blindness (Achromatopsia) - Nyctalopia (Oguchi disease) - Blindness/Low vision
Pupil Anisocoria - Argyll Robertson pupil - Marcus Gunn pupil/Marcus Gunn phenomenon - Adie syndrome
Infectious diseases Trachoma - Onchocerciasis
Other Nystagmus - Miosis - Mydriasis - Glaucoma - Ocular hypertension - Floater - Leber's hereditary optic neuropathy - Red eye - Keratomycosis - Xerophthalmia - Aniridia
See also congenital
Refraction error, also known as refractive error, is an error in the focusing of light by the eye and a frequent reason for reduced visual acuity. ... Hyperopia, also known as hypermetropia or colloquially as farsightedness or longsightedness, is a defect of vision caused by an imperfection in the eye (often when the eyeball is too short or when the lens cannot become round enough), causing inability to focus on near objects, and in extreme cases causing... Astigmatism is an affliction of the eye, where vision is blurred by an irregularly shaped cornea. ... Anisometropia is a condition in which the lenses of the two eyes have different focal lengths; that is, are in different states of myopia (nearsightedness) and hyperopia (farsightedness). ... The following text is a summary of Optical Diagnostics aniseikonia information webpage. ... Presbyopia (Greek word presbyteros (πρεσβύτερος), meaning elder) is the eyes diminished ability to focus that occurs with aging. ... This article is about the visual condition. ... Amblyopia, or lazy eye, is a disorder of the eye. ... Lebers congenital amaurosis is a rare inherited eye disease that appears at birth or in the first few months of life, typically characterized by nystagmus, sluggish or no pupillary responses, and severe vision loss or blindness. ... ... Hemeralopia is the exact opposite of Nyctalopia (Night Blindness). ... Photophobia (also light sensitivity) or fear of light, is a symptom of excessive sensitivity to light and the aversion to sunlight or well-lit places. ... Scintillating scotoma is the most common visual aura preceding migraine and was first described by 19th century physician Hubert Airy (1838–1903). ... Diplopia, commonly known as double vision, is the perception of two images from a single object. ... The word scotoma is derived from the Greek word for darkness. ... An anopsia (or anopia) is a defect in the visual field. ... Paris as seen with full visual fields Binasal hemianopia is the medical description of a type of partial blindness that is associated with certain lesions of the eye, and of the central nervous system, such as congenital hydrocephalus. ... Paris as seen with full visual fields Paris as seen with bitemporal hemianopsia Bitemporal hemianopsia is the medical description of a type of partial blindness that is associated with lesions of the optic chiasm, the area where the optic nerves from the right and left eyes cross near the pituitary... Homonymous hemianopsia is a medical term for a type of partial blindness resulting in a loss of vision in the same visual field of both eyes. ... Quadrantanopia (or quadrant anopia, as two words) refers to an anopia affecting a quarter of the field of vision. ... Color blindness in humans is the inability to perceive differences between some or all colors that other people can distinguish. ... Achromatopsia is the inability to see color. ... Nyctalopia (Greek for night blindness) is a condition making it difficult or impossible to see in relatively low light. ... This article is about the visual condition. ... Low vision is alternatively a general term used to describe lowered visual acuity, and a specific legal term in Canada and the United States used to designate someone with vision of 20/70 or less in the better eye with correction. ... The human eye The pupil is the central transparent area (showing as black). ... Anisocoria is a condition characterized by an unequal size of the pupils. ... Argyll Robertson pupils (“AR pupils”) are bilateral small pupils that constrict when the patient focuses on a near object (they “accommodate” with near vision), but do not constrict when exposed to bright light (they do not “react” to light). ... The pupil dilates instead of constricting when the light moves from the good eye to the bad eye. ... Marcus Gunn Phenomenon (a. ... Adie syndrome, also Adies syndrome, is caused by damage to the postganglionic fibers of the parasympathetic innervation of the eye and characterized by a tonically dilated pupil. ... An infection is the detrimental colonization of a host organism by a foreign species. ... Binomial name Onchocerca volvulus Bickel 1982 Onchocerciasis (pronounced ) or river blindness is the worlds second leading infectious cause of blindness. ... Nystagmus is involuntary eye movement that can be part of the vestibulo-ocular reflex (VOR), with the eyes moving first in the direction of the lesioned side (slow phase) followed by a quick correction (fast phase) to the opposite side or away from the lesioned side. ... Miosis should not be confused with meiosis, the cellular division process involved in sexual reproduction. ... Mydriasis is an excessive dilation of the pupil due to disease or drugs. ... Ocular hypertension (OHT) is intraocular pressure higher than normal in the absence of optic nerve damage or visual field loss . Current consensus in ophthalmology defines normal introcular pressure (IOP) as that between 10 mmHg and 21 mmHg . Elevated IOP is the most important risk factor for glaucoma, so those with... For other uses, see Floater (disambiguation). ... Leber’s hereditary optic neuropathy (LHON) or Leber optic atrophy is a mitochondrially inherited (mother to all offspring) form of acute or subacute loss of central vision that may lead to degeneration of retinal ganglion cells (RGCs) and their axons; this affects predominantly young adult males. ... In medicine, red eye is a non-specific term to describe an eye that appears red due to illness, injury, or some other condition. ... A fungal keratitis is an inflammation of the eyes cornea (called keratitis) that results from infection by a fungal organism. ... Xerophthalmia (Greek for dry eyes) is a medical condition in which the eye doesnt produce tears. ... Aniridia is a rare congenital condition characterized by the underdevelopment of the eyes iris. ...

  Results from FactBites:
 
Myopia - Wikipedia, the free encyclopedia (4091 words)
Myopia is often induced this way in various animal models to study the pathogenesis and mechanism of myopia development.
Measures of the heritability of myopia have yielded figures as high as 89%, and recent research has identified genes that may be responsible: defective versions of the PAX6 gene seem to be associated with myopia in twin studies [1].
A diagnosis of myopia is typically confirmed during an eye examination by an ophthalmologist or an optometrist.
Myopia - definition of Myopia - Labor Law Talk Dictionary (767 words)
Myopia, also known as nearsightedness or short-sightedness, is a refractive defect of the eye, where the person affected usually can see nearby objects clearly but distant objects appear blurred.
Myopia is measured in diopters; specifically, the strength of the corrective lens that must be used to enable the eye to focus distant images correctly on the retina.
Measures of the heritability of myopia have yielded figures as high as 89%, and recent research has identified genes that may be responsible: defective versions of the PAX6 gene seem to be associated with myopia in twin studies.
  More results at FactBites »


 

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