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Myopia, Signs and Symptoms, Causes, Diagnosis and Treatment.

. Chapters 0:00 Introduction 0:37 Causes of Myopia 1:47 Symptoms of Myopia 2:15 Diagnosis of Myopia 2:26 Treatment of Myopia 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] 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] 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 a refractive 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] In China the proportion of female is significantly higher than male.[10] 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.[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]