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Nearsightedness (Myopia)

The condition in which the individual does not see far distances clearly.

PubMed Health Glossary
(Source: NIH - National Cancer Institute)

About Myopia

Myopia, also known as nearsightedness, is a common type of refractive error where close objects appear clearly, but distant objects appear blurry.

How does myopia develop?

Myopia develops in eyes that focus images in front of the retina instead of on the retina, which results in blurred vision. This occurs when the eyeball becomes too long and prevents incoming light from focusing directly on the retina. It may also be caused by an abnormal shape of the cornea or lens.

Who is at risk for myopia?

Myopia can affect both children and adults. The condition affects about 25 percent of Americans. Myopia is often diagnosed in children between 8 and 12 years of age and may worsen during the teen years. Little change may occur between ages 20 to 40, but sometimes myopia may worsen with age. People whose parents have myopia may be more likely to get the condition... More about Myopia NIH - National Eye Institute

What works? Research summarized

Evidence reviews

Laser photocoagulation for treating choroidal new vessels near the centre of the retina in people with high myopia

In people with high myopia (refractive error ‐6 diopters or worse) new blood vessels can grow under the retina of the eye (choroidal neovascularisation). For decades laser coagulation has been used to destroy lesions that are not central. This review found one small study, including 70 participants, which compared laser photocoagulation with no treatment for people with this disease. This study was inadequately reported and analysed, although it suggested a benefit with photocoagulation during the first two years of follow up. Another small study compared three laser wavelengths to achieve photocoagulation of the lesion, but actually had very little power to demonstrate a difference between them as only 27 participants were included. Therefore, despite its widespread use for many years, the amount of benefit achieved with photocoagulation and the possibility that it is maintained over the years remains unknown. Furthermore, these and other studies suggest that the enlargement of the laser scar could be a potentially vision‐threatening long‐term complication after two years, since it may cause the gradual occurrence of a blind spot in the centre of the visual field due to progressive atrophy of the retina.

Laser in situ keratomileusis (LASIK) versus laser epithelial keratomileusis (LASEK) for correction of myopia: a systematic review

Bibliographic details: Qian ZG, Ke M, Huang G, Zou J.  Laser in situ keratomileusis (LASIK) versus laser epithelial keratomileusis (LASEK) for correction of myopia: a systematic review. Chinese Journal of Evidence-Based Medicine 2011; 11(5): 565-569 Available from: http://www.cjebm.org.cn/en/oa/darticle.aspx?type=view&id=201105018

Comparison of Q-value guide LASIK and standardized LASIK for the treatment of myopia: a meta-analysis

Bibliographic details: Shi JL, Feng YF, Chen SH, Wang QM.  Comparison of Q-value guide LASIK and standardized LASIK for the treatment of myopia: a meta-analysis. Chinese Journal of Experimental Ophthalmology 2011; 29(5): 437-443 Available from: http://d.wanfangdata.com.cn/Periodical_ykyj201105013.aspx

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Summaries for consumers

Laser photocoagulation for treating choroidal new vessels near the centre of the retina in people with high myopia

In people with high myopia (refractive error ‐6 diopters or worse) new blood vessels can grow under the retina of the eye (choroidal neovascularisation). For decades laser coagulation has been used to destroy lesions that are not central. This review found one small study, including 70 participants, which compared laser photocoagulation with no treatment for people with this disease. This study was inadequately reported and analysed, although it suggested a benefit with photocoagulation during the first two years of follow up. Another small study compared three laser wavelengths to achieve photocoagulation of the lesion, but actually had very little power to demonstrate a difference between them as only 27 participants were included. Therefore, despite its widespread use for many years, the amount of benefit achieved with photocoagulation and the possibility that it is maintained over the years remains unknown. Furthermore, these and other studies suggest that the enlargement of the laser scar could be a potentially vision‐threatening long‐term complication after two years, since it may cause the gradual occurrence of a blind spot in the centre of the visual field due to progressive atrophy of the retina.

Interventions to slow progression of nearsightedness in children

Nearsightedness (myopia) causes blurry vision when looking at distant objects. Approximately 33% of the population in the United States is nearsighted, and some Asian countries report that up to 80% of children are nearsighted. Several studies have examined a variety of methods (including eye drops, incomplete correction (known as 'undercorrection') of nearsightedness, multifocal lenses and contact lenses) to slow the worsening of nearsightedness.

Amblyopia in children: Overview

In some children one eye is favored by the brain because it provides a better image. If this happens, the other eye is neglected from childhood on, and it does not get the chance to fully develop. This is known as amblyopia or “lazy eye.”

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Terms to know

Cornea
The transparent part of the eye that covers the iris and the pupil and allows light to enter the inside.
Lens in the Eye
A clear disk that focuses light, as in a camera or microscope. In the eye, the lens is a clear, curved structure at the front of the eye behind the pupil. It focuses light rays that enter the eye through the pupil, making an image on the retina (light-sensitive layers of nerve tissue at the back of the eye).
Refractive Error
A defect in the focusing of light on the retina.
Retina
The light-sensitive tissue lining at the back of the eye. The retina converts light into electrical impulses that are sent to the brain through the optic nerve.

More about Nearsightedness

Photo of a young adult

Also called: Near-sighted, Near sighted, Myopic

Other terms to know: See all 4
Cornea, Lens in the Eye, Refractive Error

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