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Orthokeratology (Ortho-K): What Is It, Who Is a Candidate, and How Does It Work?

Orthokeratology, or ortho-k, refers to specially fitted, gas-permeable contact lenses that reshape the cornea and deliver improved vision, especially to people who are nearsighted.

contact lens

Eye doctors consider people who have myopia (nearsightedness) and those who have slight astigmatisms as good candidates for ortho-k.

Treatment can include multiple pairs of lenses and can last two to three weeks before corneal correction occurs.

What Is Orthokeratology?

Ortho-k is considered one of the most effective treatments for myopia. A non-invasive procedure,  orthokeratology uses custom-fit contact lenses to temporarily treat nearsightedness (myopia).

You don’t need eye surgery to correct your refractive error with this treatment. Instead, you wear rigid but breathable therapeutic contacts overnight for better vision when you wake up.

The gas-permeable lenses change the shape of your cornea as you sleep. You should continue wearing the contacts as prescribed to preserve your improved vision.

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What Is Corneal Refractive Therapy?

The terms corneal refractive therapy (CRT) and orthokeratology (ortho-k) are interchangeable. They both involve reshaping the cornea using contact lenses to correct vision for a day or so.

How Does It Work?

The optical problem at hand involves abnormal changes in the shape of your cornea (the transparent layer over the front of the eye). The anomaly can inhibit your eye’s ability to focus light, causing a refractive error such as nearsightedness.

CRT or ortho-K lenses correct this problem by reversing changes in the geometry of your cornea. Surgeons use an imaging technique called corneal topography to capture the shape of your cornea. Then they use topographical data to design and make a custom-fit gas-permeable lens for your eye.

At night, you wear prescription CRT lens. Overnight, your reshaped cornea gets better at focusing light into your eye. You wake up with improved vision and should typically remove the lens as you don’t need it during the day.

Your cornea will revert to its anomalous shape when you stop wearing the lenses, bringing back your vision problem.

What Does It Treat?

While ortho-k lenses correct various refractive errors, they’re most effective for near vision. Eye doctors can prescribe these lenses for other vision problems such as:

  • Distant vision (hyperopia)
  • Mismatched curves of the cornea (astigmatism)
  • Age-related farsightedness (presbyopia)

Who Is a Good Candidate?

Generally, ortho-k is considered a good option for treating refractive errors within +2.00 to -6.00 diopters, with astigmatism of -1.75 D or less.

However, patients with mild-to-moderate myopia in the range of −0.75 D to −5.00 D are considered the ideal candidates. Most can achieve 90 percent near vision correction with these lenses.

An ortho-k prescription for vision problems may be appropriate in specific scenarios such as:

  • You’re not an ideal candidate for refractive surgery
  • Glasses aren’t ideal for your line work, such as being in the military
  • Your child’s vision is changing, so they can’t have refractive surgery until their vision stabilizes
  • Wearing lenses never causes you eye health issues or discomfort
  • You prefer a temporary alternative to glasses as you weigh your options, including LASIK surgery


The bulk of your vision improvement will occur the first night you sleep with your ortho-k lenses in. Smaller corrections usually follow each time you use the treatment as directed.

You may need to change your lens prescription up to three times during treatment. This routine should continue for two weeks or more until the desired vision improvement has been achieved.

After treating your myopia, you’ll wear the same lens specifications as regularly as directed to preserve your vision gains.

How Long Does Ortho Effect Last?

Ortho-k treatment results may only last a day or so, depending on your prescription. When you discontinue treatment, your refractive error eventually returns.

Outcomes & What to Expect

Ortho-k is an effective solution for near vision. Your experience with the lenses should be smooth from the outset, unless you’ve never worn these before.

Still, any discomfort the first few nights will ease quickly as you get used to the routine.

The lenses can achieve vision correction of up to 5.0 diopters in most patients with mild myopia. With lenses approved by the U.S. Food and Drug Administration (FDA), you could improve your eyesight to 20/40 or better.

Is Ortho-k Safe?

Ortho-k is as safe today as it ever has been. By incorporating breathable lenses, the treatment allows sufficient oxygen into the eye, minimizing the risk of complications. Also, use of modern 3D imaging technology to design custom-fit lenses reduces the risk of side-effects significantly.

Despite these safety enhancements, wearing ortho-k lenses may sometimes cause eye problems. Known complications include:

  • Cornea staining
  • Eye infection

Staining of the Cornea

Corneal staining can occur when the lens sticks to your cornea. To reduce the severity of this side-effect, try fenestrated lenses for a constant supply of tears.

Alternatively, apply artificial tears before removing your lenses.

Eye Infections

Wearing contact lenses exposes you to the risk of eye infections. Recommended preventive measures include:

  • Maintaining proper hand and contact lens hygiene (it’s important that children and adolescents learn proper lens handling and care)
  • Following your doctor’s instructions
  • Following-up with your doctor


Ortho-k treatment costs can vary. The final price tag is influenced by several factors, including:

  • Your eye doctor
  • Number of follow-up checkups (which can increase when there are infections or other complications)
  • Desired degree of vision correction (determines how many lens pairs your treatment requires)

While your initial costs may range from $1,000 to $4,000, you should also budget for ongoing treatment and follow-up appointments. You may need up to $500 a year in extra costs for things like eye checkups and replacement lenses.   

Who to See If You are Considering Ortho-K

The success and safety of your ortho-k treatment partly depends on your doctor’s training and competence. This is why you should look for a qualified ortho-k specialist, especially a member of a professional ophthalmology, optometry, or orthokeratology association.

Eye doctors that can treat refractive errors with ortho-k lenses include:

  • Optometrists
  • Ophthalmologists

The American Academy of Orthokeratology and Myopia Control has an online search portal to help you find a local ortho-k doctor. Alternatively, you may go to the American Academy of Ophthalmology’s doctor search page.


  1. What Is Orthokeratology? (September 2018). American Academy of Ophthalmology.

  2. Short-Term Changes in Light Distortion in Orthokeratology Subjects. (January 2015). BioMed Research International.

  3. Frequently Asked Questions. American Academy of Orthokeratology and Myopia Control.

  4. Orthokeratology: Clinical Utility and Patient Perspectives. (February 2017). Clinical Optometry.

Last Updated July 19, 2023

Note: This page should not serve as a substitute for professional medical advice from a doctor or specialist. Please review our about page for more information.

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