Error Of Refraction Symptoms
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Extramural Activities Division of Extramural Science Programs Funding Opportunity Announcements Funding Mechanisms Supported by the NEI Research at NEI All Research refractive error treatment at NEI Office of the Scientific Director Office of the Clinical Director Education Programs All Education National Eye Health Education Program Diabetic Eye Disease Education Program Glaucoma Education Program Low Vision Education Program https://nei.nih.gov/health/errors/errors Spanish-language Education Program (¡Ojo con su visión!) Vision and Aging Program Training and Jobs All Training and Jobs NEI Summer Intern Program Diversity In Vision Research & Ophthalmology (DIVRO) Student Training Programs NEI Home About NEI Health Information News and Events Grants and Funding Research at NEI Education Programs Training and Jobs Home > Eye Health Information > Refractive Errors > Facts About https://nei.nih.gov/health/errors/errors Refractive Errors Facts About Refractive Errors This information was developed by the National Eye Institute to help patients and their families search for general information about refractive errors. An eye care professional who has examined the patient’s eyes and is familiar with his or her medical history is the best person to answer specific questions. Refractive Errors Defined What are refractive errors? Refractive errors occur when the shape of the eye prevents light from focusing directly on the retina. The length of the eyeball (longer or shorter), changes in the shape of the cornea, or aging of the lens can cause refractive errors. What is refraction? Refraction is the bending of light as it passes through one object to another. Vision occurs when light rays are bent (refracted) as they pass through the cornea and the lens. The light is then focused on the retina. The retina converts the light-rays into messages that are sent through the optic nerve to the brain. The brain interprets these messages into the images we see. Frequently Asked Questions about Refractive Errors What are the different types of refractive errors? The most common types of refractive errors are myopia, hyperopia, presbyopia, and astigmatism. Myopia (nearsightedness) is a condition where objects up c
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367.0-367.2-367.9 DiseasesDB 29645 MeSH D012030 [edit on Wikidata] Refractive error, also known as refraction error, is a problem with focusing of light on the retina due to the shape of the eye.[1] The most common types of refractive error are near-sightedness, far-sightedness, astigmatism, and presbyopia. Near-sightedness results in far objects being blurry, far-sightedness result in close objects being blurry, astigmatism causes objects to appear stretched out or blurry, and presbyopia results in a poor ability to focus on close objects. Other symptoms may include double vision, headaches, and eye strain.[1] Near-sightedness is due to the length of the eyeball being too long, far-sightedness the eyeball too short, astigmatism the cornea being the wrong shape, and presbyopia aging of the lens of the eye such that it cannot change shape sufficiently. Some refractive errors are inherited from a person's parents. Diagnosis is by eye examination.[1] Refractive errors are corrected with eyeglasses, contact lenses, or surgery. Eyeglasses are the easiest and safest method of correction. Contact lenses can provide a wider field of vision; however are associated with a risk of infection. Refractive surgery permanently changes the shape of the cornea.[1] The number of people globally with refractive errors has been estimated at one to two billion. Rates vary between regions of the world with about 25% of Europeans and 80% of Asians affected.[2] Near-sightedness is the most common disorder.[3] Rates among adults are between 15-49% while rates among children are between 1.2-42%.[4] Far-sightedness more commonly affects young child and the elderly.[5][6] Presbyopia affects most people over the age of 35.[1] The number of people with refractive errors that have not been corrected was estimated at 660 million (10 per 100 people) in 2013.[7] Of these 9.5 million were blind due to the refractive error.[7] It is one of the most common causes of vision loss along with cataracts, macular degeneration, and vitamin A deficiency.[8] Contents 1 Classification 2 Risk factors 2.1 Genetics 2.2 Environmental 3 Diagnosis 4 Management 5 Epidemiology 6 References 7 External links Classification[edit] An eye that has no refractive error when viewing distant objects is said to have emmetropia or be emmetropic meaning the eye is in a state in which it can focus parallel rays of light (light from distant objects) on the retina, without using any accommodation. A distant object in this case is defined as an object 8 meters or further away from the eye. An eye that has refractive error when viewing distant objects is said to have ametropi