| Near-sightedness | |
|---|---|
| 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] |
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] 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]
References edit
- ^ a b c d e f g h i j k l m "Facts About Refractive Errors". NEI. October 2010. Archived from the original on 28 July 2016. Retrieved 30 July 2016.
- ^ a b c d e f g h i j k l Foster PJ, Jiang Y (February 2014). "Epidemiology of myopia". Eye. 28 (2): 202–8. doi:10.1038/eye.2013.280. PMC 3930282. PMID 24406412.
- ^ a b c d Pan CW, Ramamurthy D, Saw SM (January 2012). "Worldwide prevalence and risk factors for myopia". Ophthalmic & Physiological Optics. 32 (1): 3–16. doi:10.1111/j.1475-1313.2011.00884.x. PMID 22150586.
- ^ a b Ramamurthy D, Lin Chua SY, Saw SM (November 2015). "A review of environmental risk factors for myopia during early life, childhood and adolescence". Clinical & Experimental Optometry (Review). 98 (6): 497–506. doi:10.1111/cxo.12346. PMID 26497977.
- ^ a b Holden B, Sankaridurg P, Smith E, Aller T, Jong M, He M (February 2014). "Myopia, an underrated global challenge to vision: where the current data takes us on myopia control". Eye. 28 (2): 142–6. doi:10.1038/eye.2013.256. PMC 3930268. PMID 24357836.
- ^ Ledford, Al Lens, Sheila Coyne Nemeth, Janice K. (2008). Ocular anatomy and physiology (2nd ed.). Thorofare, NJ: SLACK. p. 158. ISBN 9781556427923. Archived from the original on 8 September 2017.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ Xiong S, Sankaridurg P, Naduvilath T, Zang J, Zou H, Zhu J, et al. (September 2017). "Time spent in outdoor activities in relation to myopia prevention and control: a meta-analysis and systematic review". Acta Ophthalmologica. 95 (6): 551–566. doi:10.1111/aos.13403. PMC 5599950. PMID 28251836.
- ^ Hobday R (January 2016). "Myopia and daylight in schools: a neglected aspect of public health?". Perspectives in Public Health. 136 (1): 50–5. doi:10.1177/1757913915576679. PMID 25800796.
- ^ a b c d Pan CW, Dirani M, Cheng CY, Wong TY, Saw SM (March 2015). "The age-specific prevalence of myopia in Asia: a meta-analysis". Optometry and Vision Science. 92 (3): 258–66. doi:10.1097/opx.0000000000000516. PMID 25611765.