History Of Refractive Error Correction
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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
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types of refractive error are near-sightedness, far-sightedness, astigmatism, and presbyopia. Near-sightedness results in refractive errors of the human eye far objects being blurry, far-sightedness result in close objects being blurry, astigmatism causes objects to appear stretched out or a plus lens corrects for what refractive condition 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 https://nei.nih.gov/health/errors/errors 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. https://en.wikipedia.org/wiki/Refractive_error 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 emmetr
Correction Procedures Medical Conditions Vision for Life Aesthetics About Contact Call Us Today 402.558.2211 History of Refractive Surgery About http://lasikomaha.com/about/history-of-refractive-surgery/ History of Refractive Surgery About Overview Patient Stories Our Team Practice History History of Refractive Surgery Why Choose Us? Clinical Trials Blog Careers Resources This section is an excerpt from an refractive error article written by Lance Kugler, MD: Kugler L, Wang M. Lasers in refractive surgery: history, present, and future. Applied Optics. 2010;49(25) F1-F9 Also published in: Virtual Journal for Biomedical Optics. 2010;5(13)” Introduction to human refractive error The remarkable ability of the human eye to deliver information from the world around us would not be possible without the complex optical system within its anatomic structures. The inner layer of the posterior surface of the eye is called the retina. history of refractive The retina contains cells that transmit light information to the visual cortex of the brain via the optic nerve. The optical system of the eye is responsible for focusing the incoming rays onto the center of the retina, called the fovea, in order to form a sharp, clear image. The structures responsible for the refraction of light as it enters the eye are the cornea and the crystalline lens. The cornea maintains a constant refractive power, an average of 45 diopters (1/m), corresponding to F ~ 22mm. The lens, in contrast, is able to dynamically change its refractive power and thus the focal point of the eye. In an emmetropic eye incoming photons are focused by the cornea and lens to maintain an image on the fovea. Due to the complexity of the eye’s optical system, it is common for the focal point of a given eye to be either in front of the fovea or behind the fovea. Eyes with a focal point somewhere other than the fovea are said to have refractive error, or ametropia. Figure 1 illustrates myopia, commonly known as nearsightedness, and hyperopia, or farsightedness. In a myopic eye, light rays converge in front of the retina causing a defocused image on the fovea. Conversely in a hyperopic eye the image forms behind the fovea causing a defocused image. Factors leading to the development of myo