National Institutes of Health
- The primary NIH organization for research on Refractive Errors is the National Eye Institute
A service of the U.S. National Library of Medicine 
National Institutes of Health
Refractive Errors
Also called: Farsightedness, Hyperopia, Myopia, Nearsightedness
The cornea and 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 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
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Start Here
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Facts about Refractive Errors(National Eye Institute)
- Also available in Spanish
- Refractive Errors(American Association for Pediatric Ophthalmology and Strabismus)
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Facts about Refractive Errors
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Overviews
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Facts about Astigmatism(National Eye Institute)
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Facts about Hyperopia(National Eye Institute)
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Facts about Myopia(National Eye Institute)
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Facts about Presbyopia(National Eye Institute)
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Facts about Astigmatism
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Latest News
- Outdoor Recess May Help Protect Kids from Nearsightedness(05/03/2013, HealthDay)
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Treatment
- Cornea Transplant(Mayo Foundation for Medical Education and Research)
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Corneal Modifications
(American Optometric Association)
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MedlinePlus: Eye Wear(National Library of Medicine)
- Also available in Spanish
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MedlinePlus: Laser Eye Surgery(National Library of Medicine)
- Also available in Spanish
- Other (Refractive) Surgeries(Eye Surgery Education Council)
- Phakic Intraocular Lenses(Food and Drug Administration)
- Refractive Surgery: Candidacy for Procedures(International Society of Refractive Surgery of the American Academy of Ophthalmology)
- Refractive Surgery: Procedures(International Society of Refractive Surgery of the American Academy of Ophthalmology)
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Prevention/Screening
- Distance Vision Test for Adults(Prevent Blindness America)
- Near Vision Test for Adults(Prevent Blindness America)
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What Is a Comprehensive Dilated Eye Exam?(National Eye Institute)
- Also available in Spanish
- Return to top
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Specific Conditions
- Astigmatism(Mayo Foundation for Medical Education and Research)
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Facts about the Cornea and Corneal Disease(National Eye Institute)
- Farsightedness (Hyperopia)(Mayo Foundation for Medical Education and Research)
- Nearsightedness (Myopia)(Mayo Foundation for Medical Education and Research)
- Presbyopia(Mayo Foundation for Medical Education and Research)
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Related Issues
- Abnormal Head Position(American Association for Pediatric Ophthalmology and Strabismus)
- Eye Coordination(American Optometric Association)
- How to Choose a Surgeon(Eye Surgery Education Council)
- Visual Acuity: What Is 20/20 Vision?(American Optometric Association)
- What Are the Risks and How Can I Find the Right Doctor for Me? (Refractive Surgery)(Food and Drug Administration)
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Pictures & Photographs
- Corneal transplant - slideshow
- Also available in Spanish
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Eye Examinations(National Eye Institute)
- Presbyopia(Logical Images)
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Videos
- Astigmatism(American Optometric Association)
- Hyperopia (Farsightedness)(American Optometric Association)
- Monovision(American Optometric Association)
- Presbyopia(American Optometric Association)
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Anatomy/Physiology
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Diagram of the Eye(National Eye Institute)
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Diagram of the Eye
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Financial Issues
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Financial Aid for Eye Care(National Eye Institute)
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Financial Aid for Eye Care
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Clinical Trials
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ClinicalTrials.gov: Astigmatism(National Institutes of Health)
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ClinicalTrials.gov: Hyperopia(National Institutes of Health)
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ClinicalTrials.gov: Lenses, Intraocular(National Institutes of Health)
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ClinicalTrials.gov: Myopia(National Institutes of Health)
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ClinicalTrials.gov: Presbyopia(National Institutes of Health)
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ClinicalTrials.gov: Refractive Errors(National Institutes of Health)
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ClinicalTrials.gov: Astigmatism
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Research
- Natural Light May Benefit Vision and Biorhythms(American Academy of Ophthalmology)
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Journal Articles
References and abstracts from MEDLINE/PubMed (National Library of Medicine)
- Article: Myopia and glaucoma: diagnostic and therapeutic challenges.
- Article: Effect of platelet-rich plasma in nerve regeneration after LASIK.
- Article: Laser-assisted in-situ keratomileusis (LASIK) versus photorefractive keratectomy (PRK) for myopia.
- Refractive Errors -- see more articles
- Astigmatism -- see more articles
- Farsightedness (hyperopia) -- see more articles
- Presbyopia -- see more articles
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Dictionaries/Glossaries
- Glossary of Eye-Related Terms(Foundation of the American Academy of Ophthalmology)
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Directories
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Eye Health Organizations Database(National Eye Institute)
- Also available in Spanish
- Find a Pediatric Ophthalmologist(American Association for Pediatric Ophthalmology and Strabismus)
- Find a Refractive (Eye) Surgeon(International Society of Refractive Surgery of the American Academy of Ophthalmology)
- Find an Eye M.D.(American Academy of Ophthalmology)
- Find an Optometrist(Association of Regulatory Boards of Optometry)
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Finding an Eye Care Professional(National Eye Institute)
- Also available in Spanish
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Eye Health Organizations Database
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Organizations
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Statistics
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Hyperopia(National Eye Institute)
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Myopia(National Eye Institute)
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Myopia Increasing in the U.S. Population(National Eye Institute)
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Hyperopia
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MedlinePlus Magazine
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Children
- Glasses and Contact Lenses(Nemours Foundation)
- Also available in Spanish
- Home Eye Tests For Children(Prevent Blindness America)
- Your Child's Vision(Nemours Foundation)
- Also available in Spanish
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Seniors
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Presbyopia(National Eye Institute)
- PDF
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Presbyopia
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Patient Handouts
- Astigmatism
- Also available in Spanish
- Corneal transplant
- Also available in Spanish
- Corneal transplant - discharge
- Also available in Spanish
- Farsightedness
- Also available in Spanish
- Home vision tests
- Also available in Spanish
- Nearsightedness
- Also available in Spanish
- Presbyopia
- Also available in Spanish
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Presbyopia(National Eye Institute)
- PDF
- Refraction test
- Also available in Spanish
- Refractive corneal surgery - discharge
- Also available in Spanish
- Standard ophthalmic exam
- Also available in Spanish
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You may also be interested in these related encyclopedia pages:
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