User:Mr. Ibrahem/Near-sightedness
Medical condition / From Wikipedia, the free encyclopedia
Near-sightedness, also known as short-sightedness and myopia, is an eye disorder where light focuses in front of, instead of on, the retina.[1][2] This causes distant objects to be blurry while close objects appear normal.[1] Other symptoms may include headaches and eye strain.[1] Severe near-sightedness is associated with an increased risk of retinal detachment, cataracts, and glaucoma.[2]
Near-sightedness | |
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Other names | Myopia, short-sightedness, near-sighted |
Diagram showing changes in the eye with near-sightedness | |
Specialty | Ophthalmology, optometry |
Symptoms | Distant objects appear blurry, close objects appear normal, headaches, eye strain[1] |
Complications | Retinal detachment, cataracts, glaucoma[2] |
Causes | Combination of genetic and environmental factors[2] |
Risk factors | Near work, greater time spent indoors, family history[2][3] |
Diagnostic method | Eye examination[1] |
Prevention | More time outside for children[4] |
Treatment | Eyeglasses, contact lenses, surgery[1] |
Frequency | 1.5 billion people (22%)[2][5] |
The underlying cause is believed to be a combination of genetic and environmental factors.[2] Risk factors include doing work that involves focusing on close objects, greater time spent indoors, and a family history of the condition.[2][3] It is also associated with a high socioeconomic class.[2] The underlying mechanism involves the length of the eyeball growing too long or less commonly the lens being too strong.[1][6] It is a type of refractive error.[1] Diagnosis is by eye examination.[1]
Tentative evidence indicates that the risk of near-sightedness can be decreased by having young children spend more time outside.[4][7] This may be related to natural light exposure.[8] Near-sightedness can be corrected with eyeglasses, contact lenses, or surgery.[1] Eyeglasses are the easiest and safest method of correction.[1] Contact lenses can provide a wider field of vision, but are associated with a risk of infection.[1] Refractive surgery permanently changes the shape of the cornea.[1]
Near-sightedness is the most common eye problem and is estimated to affect 1.5 billion people (22% of the population).[2][5] Rates vary significantly in different areas of the world.[2] Rates among adults are between 15% to 49%.[3][9] Rates are similar in females and males.[9] Among children, it affects 1% of rural Nepalese, 4% of South Africans, 12% of Americans, and 37% in some large Chinese cities.[2][3] Rates have increased since the 1950s.[9] Uncorrected near-sightedness is one of the most common causes of vision impairment globally along with cataracts, macular degeneration, and vitamin A deficiency.[9]