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
Your cornea is the clear front part of your eye. It is like a window that controls and focuses the light coming into the eye. If your cornea has an irregular shape, the light does not focus properly. Everything looks blurry. This is a refractive error.
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
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 Refractive Errors(National Eye Institute)
- Also available in Spanish
- Refractive Errors(American Association for Pediatric Ophthalmology and Strabismus)
-
Facts about Refractive Errors
The top row in the table of contents box contains the following groups:
Basics
,
Learn More
, and
Multimedia & Cool Tools
.
For group Basics
For group Learn More
For group Multimedia & Cool Tools
The bottom row in the table of contents box contains the following groups:
Research
,
Reference Shelf
, and
For You
.
For group Research
For group Reference Shelf
For group For You
-
Overviews
-
Facts about Astigmatism(National Eye Institute)
-
Facts about Hyperopia(National Eye Institute)
-
Facts about Myopia(National Eye Institute)
-
Facts about Presbyopia(National Eye Institute)
-
Facts about Astigmatism
-
Treatment
- Cornea Transplant(Mayo Foundation for Medical Education and Research)
-
Corneal Modifications
(American Optometric Association)
-
MedlinePlus: Eye Wear(National Library of Medicine)
-
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)
-
Prevention/Screening
- Distance Vision Test for Adults(Prevent Blindness America)
- Near Vision Test for Adults(Prevent Blindness America)
-
What Is a Comprehensive Dilated Eye Exam?(National Eye Institute)
-
Specific Conditions
- Astigmatism(Mayo Foundation for Medical Education and Research)
- Eye Coordination(American Optometric Association)
-
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)
- Return to top
-
Related Issues
- Abnormal Head Position(American Association for Pediatric Ophthalmology and Strabismus)
- How to Choose a Surgeon(Eye Surgery Education Council)
- Refractive Surgery: What Are the Risks and How Can I Find the Right Doctor for Me?(Food and Drug Administration)
- Visual Acuity: What Is 20/20 Vision?(American Optometric Association)
- Return to top
-
Pictures & Photographs
- Corneal transplant - slideshow
- Also available in Spanish
-
Eye Examinations(National Eye Institute)
- Presbyopia(Logical Images)
- Return to top
-
Videos
- Astigmatism(American Optometric Association)
- Hyperopia (Farsightedness)(American Optometric Association)
- Monovision(American Optometric Association)
- Presbyopia(American Optometric Association)
- Return to top
-
Anatomy/Physiology
-
Diagram of the Eye(National Eye Institute)
- Also available in Spanish
- Return to top
-
Diagram of the Eye
-
Financial Issues
-
Financial Aid for Eye Care(National Eye Institute)
- Also available in Spanish
- Return to top
-
Financial Aid for Eye Care
-
Clinical Trials
-
ClinicalTrials.gov: Astigmatism(National Institutes of Health)
-
ClinicalTrials.gov: Hyperopia(National Institutes of Health)
-
ClinicalTrials.gov: Lenses, Intraocular(National Institutes of Health)
-
ClinicalTrials.gov: Myopia(National Institutes of Health)
-
ClinicalTrials.gov: Presbyopia(National Institutes of Health)
-
ClinicalTrials.gov: Refractive Errors(National Institutes of Health)
- Return to top
-
ClinicalTrials.gov: Astigmatism
-
Research
- More Time Outdoors May Reduce Kids' Risk for Nearsightedness(American Academy of Ophthalmology)
- Natural Light May Benefit Vision and Biorhythms(American Academy of Ophthalmology)
-
Study Estimates Prevalence of Vision Disorders among Preschool Children in Three Ethnic Groups(National Eye Institute)
- Return to top
-
Journal Articles
References and abstracts from MEDLINE/PubMed (National Library of Medicine)
- Article: A contralateral, randomized comparison of optimized prolate ablation and conventional...
- Article: Comparison of dry-eye disease severity after laser in situ keratomileusis...
- Article: Foldable iris-fixated phakic intraocular lens vs femtosecond laser-assisted LASIK for...
- Refractive Errors -- see more articles
- Astigmatism -- see more articles
- Farsightedness (hyperopia) -- see more articles
- Presbyopia -- see more articles
- Return to top
-
Dictionaries/Glossaries
- Glossary of Eye-Related Terms(Foundation of the American Academy of Ophthalmology)
- Return to top
-
Directories
-
Eye Health Organizations Database(National Eye Institute)
- 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)
-
Finding an Eye Care Professional(National Eye Institute)
- Also available in Spanish
- Return to top
-
Eye Health Organizations Database
-
Organizations
-
Statistics
-
Myopia Increasing in the U.S. Population(National Eye Institute)
- Return to top
-
Myopia Increasing in the U.S. Population
-
MedlinePlus Magazine
-
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
- Return to top
-
Seniors
-
Presbyopia(National Eye Institute)
- PDF
- Return to top
-
Presbyopia
-
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
-
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
- Return to top
-
You may also be interested in these related encyclopedia pages:
MEDICAL ENCYCLOPEDIA
