Health Topic

Refractive Errors

Are you nearsighted, farsighted, or have astigmatism? That's a refractive error, caused by an irregular-shaped cornea or lens. Learn how it's treated.

Reviewed Reviewed by a registered pharmacistGeneral information

Also called: Farsightedness · Hyperopia · Myopia · Nearsightedness

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Refractive Errors

The cornea and lens of your eye bend (refract) light rays to focus them on the retina. Refractive errors happen when the shape of your eye prevents light from focusing correctly on the retina. This causes blurry vision. Changes in the eye's shape affect how light rays bend and focus, leading to vision problems.

Refractive errors can happen when:

  • The eyeball is too long or too short.
  • The cornea changes shape.
  • The lens becomes less flexible as you age.

Each type of refractive error is different, but they all make it hard to see clearly.

Four common types of refractive errors include:

  • Nearsightedness (myopia), blurred vision when looking at faraway objects.
  • Farsightedness (hyperopia), blurred vision when looking at close-up objects.
  • Astigmatism, blurred or distorted vision at all distances, which can make night vision harder.
  • Presbyopia, difficulty seeing things up close because the lens becomes less flexible with age. It affects adults in middle age and older and often begins around age 45.

Anyone can have refractive errors. It's the most common type of vision problem. You may be more likely to have one if other family members wear glasses or contact lenses.

Most types of refractive errors start in childhood or are present at birth. Presbyopia is different. Nearly everyone develops it as they age, typically starting around age 45.

Sometimes you may not notice vision changes right away, which is why regular eye exams are so important.

The most common symptom is blurred vision. Other symptoms may include:

  • Double vision
  • Haziness
  • Glare or halos around bright lights
  • A need to squint to see clearly
  • Headaches
  • Eye strain or tired eyes
  • Difficulty focusing when reading or using a computer

If you already wear glasses or contact lenses and notice these symptoms, you may need a new prescription. Tell your eye care specialist if your vision changes or if you have problems with your glasses or contact lenses

An eye care specialist can diagnose refractive errors during a comprehensive eye exam. You'll be tested to see how well you can see at different distances, both with and without corrective lenses (glasses or contact lenses). Your provider may also use special eye drops to dilate (widen) your pupils to check for other eye conditions.

Different eye care specialists may be involved in your care. Here are some of the most common:

  • Ophthalmologists are medical doctors who treat eye diseases, prescribe glasses or contact lenses, and perform eye surgery.
  • Optometrists perform eye exams, diagnose vision problems, and prescribe glasses or contact lenses.
  • Opticians fit or adjust glasses or contact lenses based on a prescription from your eye care specialist.

Refractive errors are usually easy to correct with:

  • Glasses
  • Contact lenses
  • Laser eye surgery, in some cases

Your eye care specialist can help choose the best treatment for your vision and lifestyle.

It sits within Eyes and Vision.

The lead U.S. institute for this subject is the National Eye Institute.

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Research on Refractive Errors

1,912 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

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Diagnosis and Tests

Treatments and Therapies

Prevention and Risk Factors

Related Issues

Genetics

Statistics and Research

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Refractive Errors. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Refractive Errors, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.