Eye Refractive Error
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What Is Considered A High Refractive Error
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Refractive Error Correction
Conditions Refractive Errors Refractive Errors Reviewed by Jill E. Bixler, M.D. On this page: What Is a
Refractive Error In Children
Refractive Error? Symptoms Causes Risk Factors Tests and Diagnosis Treatment and Drugs Clinic Information What Is a Refractive Error? Refractive error means that the shape of your eye does https://nei.nih.gov/health/errors/errors not bend light correctly, resulting in a blurred image. The main types of refractive errors are myopia (nearsightedness), hyperopia (farsightedness), presbyopia (loss of near vision with age), and astigmatism. Symptoms Blurred vision Difficulty reading or seeing up close Crossing of the eyes in children (esotropia) Causes Overuse of the eyes does not cause or worsen refractive error. http://kellogg.umich.edu/patientcare/conditions/refractive.errors.html The causes of the main types of refractive error are described below: Myopia(close objects are clear, and distant objects are blurry) Also known as nearsightedness, myopia is usually inherited and often discovered in childhood. Myopia often progresses throughout the teenage years when the body is growing rapidly. Watch a video explaining myopia. Hyperopia (close objects are more blurry than distant objects) Also known as farsightedness, hyperopia can also be inherited. Children often have hyperopia, which may lessen in adulthood. In mild hyperopia, distance vision is clear while near vision is blurry. In more advanced hyperopia, vision can be blurred at all distances. Watch a video explaining hyperopia. Presbyopia (aging of the lens in the eye) After age 40, the lens of the eye becomes more rigid and does not flex as easily. As a result, the eye loses its focusing ability and it becomes more difficult to read at close range. This normal aging process of the lens can also be combined with myopia, hyperopia or astigmatism. Watch a video exp
Instructions Laser Vision Correction LASIK Technology LASIK Testimonials Online Appointment LASIK Downloads Corneal surgery handbook LASIK Follow-Up Form LASIK@SN Back to LASIK Main Page LASIK CORNER What is Refractive Error? Normally, the rays of light entering the http://www.sankaranethralaya.org/lasik-refractive-errors.html eye are brought to a precise focus on the retina – the light sensitive layer lining the back of the eye. When such a focus is not achieved, a refractive error results and vision is not clear. These http://www.visionaware.org/info/your-eye-condition/guide-to-eye-conditions/refractive-error-and-astigmatism/125 imperfections in the focusing power of the eye are called refractive errors. The common refractive errors are: Myopia, or Nearsightedness; Hyperopia, or Farsightedness; Astigmatism Myopia: A myopic eye is longer than normal or has a cornea that refractive error is too steep, as a result of which the light rays focus in front of the retina. Close objects look clear, but distant objects appear blurred. Hyperopia (Farsightedness): Hyperopia is a term used to describe the condition of farsightedness. The causes of hyperopia are typically genetic and involve an eye that is too short or a cornea that is too flat, as a result of which images focus at a point behind the Retina. of refractive error People with hyperopia can usually see distant objects well, but have trouble focussing on nearby objects Astigmatism (Distorted vision): courtesy : Allergan ; Eye Calender ASTIGMATISM (cylindrical error) occurs when the incoming light rays are unable to reach a common focus within the eye. Astigmatism distorts or blurs vision for both near and far objects. The cornea is the clear front window of the eye. A normal cornea is round and smooth, like a basketball. When you have astigmatism, the cornea curves more in one direction than in the other, like a football. It is possible to have astigmatism in combination with myopia or hyperopia. Our Websites Support Sankara Nethralaya Home Ophthalmic Links SN Kolkata SN Omtrust About Us LASIK International Patient Services Omlog Patient Care Feed Back Vision & Mission Statement The Sankara Nethralaya Academy Education Career PROSE-(Boston scleral lenses) Ekalavya Research Eye Bank e-Learning Elite School of Optometry Publications Community Ophthalmology Library Ofisa Teleophthalmology Future Events & Conference Last Updated on : 15/10/2016 Designed and Maintained by Sankara Nethralaya Copyright © Medical Research Foundation. All rights reserved. Sitemap Sankara Nethralaya (Main Campus) No. 18, College Road, Nungambakkam, Chennai - 600 006, Tamil Nadu , India. Ph No: +91-044-42271500, Fax No: +91-44-28254180 e-mail id : mrf@snmail.org, information@snmail.org This Site best viewed at 1024 x 768 resolution in I.E 7 or
Degeneration (AMD)CataractsDiabetes and Diabetic RetinopathyGlaucomaRetinitis PigmentosaGuide to Eye ConditionsGlossary of Vision-Related TerminologyEmotional SupportPersonal StoriesHandling the NewsHelp Others Understand Your Vision ProblemsCoping with Vision LossFor Family and FriendsSupport Groups and Other ResourcesWorking with People New to Visual ImpairmentEveryday LivingEssential SkillsHelpful Products and TechnologyHome Modification Recreation and LeisureHome RepairsTransportationVisionAware VideosWorking LifeTalking to Your EmployerKnow Your RightsTraining ResourcesWorkplace TechnologyCareerConnect StoriesWorking as a Senior with Vision LossFor SeniorsAge-Related Vision Loss Life Changes Health and AgingRetirement LivingContinuing to Work as a Senior with Vision LossGet ConnectedAbout VisionAwareJoin the CommunityCalendar of EventsMessage BoardsBlogNewsletterAnnouncementsPeer AdvisorsHomeYour Eye ConditionGuide to Eye ConditionsRefractive Error and AstigmatismRefractive Error and AstigmatismBy Mrinali Patel Gupta, M.D. What Is Refractive Error? The power of your eye to focus and see an image clearly is dependent on several structures within the eye: The cornea is a transparent dome-shaped tissue that forms the front part of the eye. It functions as a window and allows light to enter the eye. It also begins the process of focusing light rays that allow you to see words and images clearly. The lens is composed of transparent, flexible tissue, located directly behind the iris and the pupil. It is the second part of the eye, after the cornea, which helps to focus light and images on the retina. Because the lens is flexible and elastic, it can change its curved shape to focus on objects and people that are either nearby or at a distance. In order to see as clearly as possible, images must be focused by the cornea and lens directly onto the retina, the light-sensitive tissue that lines the inside surface of the eye, much like the film in a camera. Visual information is transmitted from the retina to the brain by the optic nerve. In order for vision to be as sharp as possible, the focusing power of the lens and cornea must correspond appropriately to the length of the eye so that the light rays ultimately come together at the retina. If they focus either in front of the retina or behind the retina, the image will not be as clear as possible, and there will be refractive error. Myopia or Near-Sightedness People with myopia, or near-sightedness, can see close-up objects clearly, but distant objects are blurred. In myopia, light rays are brought to