Myopia

Myopia, also known as nearsightedness (alternatively, near-sightedness) and short-sightedness, is an eye condition where light from distant objects focuses in front of, instead of on, the retina. As a result, distant objects appear blurry, while close objects appear normal. Other symptoms may include headaches and eye strain. Severe myopia is associated with an increased risk of macular degeneration, retinal detachment, cataracts, and glaucoma. Myopia results from the length of the eyeball growing too long or less commonly the lens being too strong. It is a type of refractive error. Diagnosis is by the use of cycloplegics during eye examination. Myopia is less common in people who spent more time outside during childhood. This lower risk may be due to greater exposure to sunlight. Myopia can be corrected with eyeglasses, contact lenses, or by refractive surgery. Eyeglasses are the simplest and safest method of correction. Contact lenses can provide a relatively wider corrected field of vision, but are associated with an increased risk of infection. Refractive surgeries such as LASIK and PRK permanently change the shape of the cornea. Other procedures include implantable collamer lens (ICL) placement inside the anterior chamber in front of the natural eye lens. ICL does not affect the cornea. Myopia is the most common eye disorder and is estimated to affect 1.5 billion people (22% of the world population). Rates vary significantly in different areas of the world. Rates among adults are between 15% and 49%. 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. In China the proportion of girls is slightly higher than boys. Rates have increased since the 1950s. Uncorrected myopia is one of the most common causes of vision impairment globally along with cataracts, macular degeneration, and vitamin A deficiency.