Eye Problems Refractive Error
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Tools EspaƱol You Are Here: Home → Health Topics → Refractive Errors URL of this page: https://medlineplus.gov/refractiveerrors.html Refractive Errors Also called: Farsightedness, Hyperopia, Myopia, Nearsightedness To use the types refractive errors sharing features on this page, please enable JavaScript. On this page Basics
Refractive Error Treatment
Summary Start Here Latest News Diagnosis and Tests Prevention and Risk Factors Treatments and Therapies Learn More Related refractive errors ppt Issues Specifics Genetics See, Play and Learn Images Research Statistics and Research Clinical Trials Journal Articles Resources Reference Desk Find an Expert For You Children Patient Handouts Summary The cornea and refractive error in children lens of your eye helps you focus. Refractive errors are vision problems that happen when the shape of the eye keeps you from focusing well. The cause could be the length of the eyeball (longer or shorter), changes in the shape of the cornea, or aging of the lens. Four common refractive errors are Myopia, or nearsightedness - clear vision close
Refractive Error Correction
up but blurry in the distance Hyperopia, or farsightedness - clear vision in the distance but blurry close up Presbyopia - inability to focus close up as a result of aging Astigmatism - focus problems caused by the cornea The most common symptom is blurred vision. Other symptoms may include double vision, haziness, glare or halos around bright lights, squinting, headaches, or eye strain. Glasses or contact lenses can usually correct refractive errors. Laser eye surgery may also be a possibility. NIH: National Eye Institute Start Here Facts about Astigmatism (National Eye Institute) Also in Spanish Facts about Hyperopia (National Eye Institute) Also in Spanish Facts about Myopia (National Eye Institute) Also in Spanish Facts about Presbyopia (National Eye Institute) Facts about Refractive Errors (National Eye Institute) Also in Spanish Refractive Errors (American Association for Pediatric Ophthalmology and Strabismus) Also in Spanish Latest News Undiagnosed Eye Problems Pose Risks for Migrant Farm Workers (10/10/2016, HealthDay) Diagnosis and Tests Dilating Eye Drops (American Association for Pediatric Ophthalmology and Strabismus) Also in Spanish Near Vision Test for Adults (Prevent Blindness America) Retinoscopy (
Care Sub-Section Eye Clinics Make an Appointment How to Find Us Eye Conditions Find a Doctor Navigation: Eye Conditions Eye Conditions Video Library FAQ "Ask the Expert" Ophthalmology Links Search the Kellogg website refractive errors pdf Navigation: Breadcrumbs Home Patient Care Eye Conditions Refractive Errors Refractive Errors Reviewed refractive errors of the human eye by Jill E. Bixler, M.D. On this page: What Is a Refractive Error? Symptoms Causes Risk Factors Tests and
Refractive Error Measurement
Diagnosis Treatment and Drugs Clinic Information What Is a Refractive Error? Refractive error means that the shape of your eye does not bend light correctly, resulting in a blurred image. The https://medlineplus.gov/refractiveerrors.html 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. The causes of the main types of refractive error are described below: Myopia(close objects are clear, http://kellogg.umich.edu/patientcare/conditions/refractive.errors.html 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 explaining presbyopia. Astigmatism Astigmatism usually occurs when the front surface of the eye, the cornea, has an asymmetric curvature. Normally the cornea is smooth and equally curved in all directions, and light entering
often are the main reason a person seeks the services of an optometrist or ophthalmologist. But what does it really mean when we're told that our vision is blurry because we have a refractive error? We see the world around us because of http://www.allaboutvision.com/eye-exam/refraction.htm the way our eyes bend (refract) light. Refractive errors are optical imperfections that prevent the eye from properly focusing light, causing blurred vision. The primary refractive errors are nearsightedness, farsightedness and astigmatism. Refractive errors usually can be "corrected" with eyeglasses or http://www.visionaware.org/info/your-eye-condition/guide-to-eye-conditions/refractive-error-and-astigmatism/125 contact lenses, or they can be permanently treated with LASIK and other vision correction surgery (also called refractive surgery). FIND A DOCTOR: Do you have a refractive error? Find an eye doctor near you to have your eyes checked. > refractive error How Light Travels Through the Eye In order to see, we must have light. While we don't fully understand all the different properties of light, we do have an idea of how light travels. Watch this video on what causes blurry vision and how we can correct it. A light ray can be deflected, reflected, bent or absorbed, depending on the different substances it encounters. When light travels through water or a lens, for example, its path is bent or refracted. Certain eye problems refractive eye structures have refractive properties similar to water or lenses and can bend light rays into a precise point of focus essential for sharp vision. Most refraction in the eye occurs when light rays travel through the curved, clear front surface of the eye (cornea). The eye's natural (crystalline) lens also bends light rays. Even the eye's tear film and internal fluids (aqueous humor and vitreous) have refractive abilities. Recommended For You Say goodbye to discomfort with ULTRA contact lenses Learn how Optometry Giving Sight helps 670 million people to see again Questions about cataracts? Find all the answers in My Cataract Journey Save 10-30% off your eye exam using the BenefitsPal™ card How the Eye Sees The process of vision begins when light rays that reflect off objects and travel through the eye's optical system are refracted and focused into a point of sharp focus. For good vision, this focus point must be on the retina. The retina is the tissue that lines the inside of the back of the eye, where light-sensitive cells (photoreceptors) capture images in much the same way that film in a camera does when exposed to light. These images then are transmitted through the eye's optic nerve to the brain for interpretation. Just as a camera's aperture (called the diaphragm) is used to adjust the amount of light needed to expose film in just the right way, the eye's pupil widens or constricts to control the amount
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