Orthokeratology (Ortho-K): How Overnight Lenses Reshape Your Vision

Oct 29

9 min read

Updated: 6 days ago

Written and medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026 · How we review

Quick Answer: What is orthokeratology (ortho-k)?

Orthokeratology (ortho-k) is a vision treatment that uses rigid gas permeable contact lenses worn overnight to gently flatten and reshape the cornea, so you can see clearly during the day without glasses or contacts. It mainly treats nearsightedness, can slow fast-worsening myopia in children, and requires nightly wear because the effect fades. Eye infection is the main risk. [1]

What the research says

Ortho-k slows eye growth in nearsighted children. A Cochrane review of 104 randomized trials in 17,509 children found that ortho-k reduced axial elongation (eye lengthening) by 0.18 mm over one year compared with controls, with moderate-certainty evidence. (Lawrenson et al., Cochrane Database Syst Rev, 2025) [2]
The benefit lasts only while the lenses are worn. A meta-analysis of 45 papers found eye growth in children was 0.16 mm lower with ortho-k than with other treatments at one year, but eye growth sped up again (by 0.10 mm) after children stopped ortho-k. Ortho-k wearers were up to 3.79 times more likely to have an adverse event than conventional contact lens wearers. (Sartor et al., Int Ophthalmol, 2024) [3]
Infection risk is similar to other overnight lenses. A systematic review of 170 publications found the risk of microbial keratitis (a serious corneal infection) with ortho-k was similar to other overnight lens wear, and the most common complication was corneal staining. (Liu & Xie, Eye Contact Lens, 2016) [4]

Key takeaways

Ortho-k lenses are rigid contact lenses you wear while you sleep and remove in the morning. [1]
They gently flatten the front of the eye, much like a retainer reshapes teeth. [1]
Eye doctors mainly use ortho-k for nearsightedness, and sometimes for children whose vision is worsening quickly. [1]
Results take a few weeks, and blurry vision returns if you skip nights. [1]
Eye infection is the main concern, and good hand and lens hygiene helps prevent it. [1]

Orthokeratology at a glance

Question	Answer
What it is	Overnight rigid gas permeable (RGP) contact lenses that reshape the cornea [1]
Main use	Nearsightedness (myopia) [1]
Also used for	Children whose vision is getting worse quickly [1]
When you wear them	At night, while you sleep [1]
Time to see results	Usually a few weeks of nightly wear [1]
Is it permanent?	No. The cornea returns to its natural shape if you stop [1]
Main risk	Eye infection [1]
Common early side effects	Discomfort and trouble sleeping for the first few days [1]

How does orthokeratology work?

Orthokeratology works by using rigid lenses to gently flatten the cornea, the clear front surface of the eye, while you sleep. [1] The lenses are rigid gas permeable (RGP) contacts, and their firm shape presses the cornea into a new curve overnight. [1]

Think of ortho-k as a retainer for your eyes. A dental retainer holds teeth in position. Ortho-k lenses hold the cornea in a flatter shape. [1]

In a nearsighted eye, light focuses in front of the retina, so distant objects look blurry. After ortho-k reshapes the cornea, light can focus more clearly, and you take the lenses out in the morning and see without glasses or daytime contacts. [1] Read more about how the cornea bends light and about refractive errors.

Diagram showing how orthokeratology lenses flatten the cornea overnight so light focuses on the retina for clear daytime vision

How ortho-k reshapes the cornea: a nearsighted eye, overnight lens wear, and clear daytime focus.

Who is orthokeratology for?

Orthokeratology is mainly for people with nearsightedness who do not want to wear glasses or contact lenses during the day. [1] Eye doctors most often suggest it to manage myopia. [1]

Ortho-k may also suit children whose eyesight is getting worse quickly. [1] Because a child's eyes are still growing, the lenses can help slow changes in the cornea as they grow. [1]

Only an eye doctor can tell you whether ortho-k fits your eyes. If you wear glasses today, our guide to eyeglasses, lens types and care explains the alternative.

Can orthokeratology slow myopia in children?

Orthokeratology can slow worsening nearsightedness in children, which is one of the main reasons eye doctors prescribe it. [1] In randomized trials, ortho-k reduced eye lengthening by 0.18 mm over one year compared with children in control groups. [2]

That benefit depends on staying with the treatment. Eye growth in children sped up again after they stopped wearing ortho-k lenses. [3] Researchers still debate how long treatment should continue and who should start it. [5]

Your child's eye doctor will explain how long treatment is needed. A child's vision may stabilize, but they may still need some vision correction. [1]

Slowing myopia in childhood matters because high myopia later in life can lead to problems such as myopic degeneration. For a parent-friendly overview of all options, see this guide to myopia control in children.

Finding	Result
Eye growth vs. controls (1 year)	0.18 mm less with ortho-k [2]
Eye growth vs. other treatments (1 year)	0.16 mm less with ortho-k [3]
After stopping ortho-k	Eye growth sped up by 0.10 mm vs. continuing [3]

What are the benefits and risks of orthokeratology?

The main benefit of orthokeratology is clear daytime vision without glasses or contacts, and the main risk is eye infection. [1] It is a simple option to try for people who do not want to wear glasses or daytime lenses. [1]

Benefits	Risks and downsides
Clear vision during the day without glasses or contacts [1]	Eye infection is the main concern [1]
Can help slow worsening nearsightedness in children [1]	Lenses can feel uncomfortable at first [1]
The effect is reversible if you stop [1]	Can make it hard to fall or stay asleep at first [1]
Simple to try under an eye doctor's care [1]	Vision blurs again if you skip nights [1]

Eye infection is the risk to take most seriously. Washing your hands before touching your eyes or lenses, and cleaning the lenses exactly as instructed, helps prevent it. [1] Research shows the risk of serious corneal infection is similar to other overnight lens wear, and long-term success depends on proper fitting, strict lens care and regular follow-ups. [4] Learn the warning signs in our eye infection guide and our article on acanthamoeba keratitis, a rare infection linked to contact lens use. For safe-wear tips for young lens users, see this guide for parents on children and contact lenses.

Infographic comparing the benefits and risks of orthokeratology, including clear daytime vision and the risk of eye infection

Ortho-k benefits and risks side by side.

How long does orthokeratology take to work?

Orthokeratology usually takes a few weeks of nightly wear before you notice clearer vision. [1] The change does not happen after the first night. [1]

The first few days can feel strange. The rigid lenses may feel uncomfortable and may make it harder to fall or stay asleep, but most people adjust within a few days. [1]

Stage	What to expect
First few nights	Lenses may feel uncomfortable; sleep may be disturbed [1]
First few days	Most people adjust to the feel of the lenses [1]
First few weeks	Daytime vision gradually improves [1]
Ongoing	Nightly wear keeps vision clear [1]

Timeline of the ortho-k routine from eye exam and nightly wear to clearer daytime vision after a few weeks

The ortho-k routine and when to expect results.

What happens if you stop wearing ortho-k lenses?

If you stop wearing ortho-k lenses, your corneas return to their natural shape and blurry vision comes back. [1] This can happen after just a few missed nights. [1]

In children, stopping treatment also matters for eye growth. Studies show eye lengthening speeds up again after ortho-k is stopped. [3] Talk to your eye doctor before pausing or ending treatment.

When should you call an eye doctor about ortho-k?

You should see an eye doctor right away if you think you have an eye infection while using ortho-k. [1] Your doctor may tell you to stop wearing the lenses until the infection clears. [1]

Also contact your eye doctor if:

Your vision changes [1]
You feel pain during or after wearing the lenses [1]
You have questions about how long treatment should last, especially for a child [1]

Conclusion

Orthokeratology is a way to see clearly during the day by reshaping your cornea at night with rigid contact lenses. It works best for nearsightedness, it can help slow fast-worsening myopia in children, and it lasts only as long as you keep wearing the lenses every night. Eye infection is the main risk, so careful hand washing and lens cleaning are not optional.

If ortho-k sounds right for you or your child, book an exam with an eye doctor to find out whether your eyes are a good fit. Keep learning with our guides to refractive errors, astigmatism and scleral lenses, and explore more clear, research-backed eye health articles across Rinnit.com.

FAQ

Is orthokeratology permanent?

Orthokeratology is not permanent. The cornea slowly returns to its natural shape when you stop wearing the lenses, and blurry vision can come back after just a few missed nights in a row. That is why ortho-k works only as long as you keep up the nightly routine your eye doctor sets. [1]

How long does it take for ortho-k to work?

Ortho-k usually takes a few weeks of nightly wear before your vision clearly improves. Your eye doctor will tell you what to expect for your eyes. The change is gradual, so keep wearing the lenses every night even if you do not notice a difference in the first days. [1]

Do ortho-k lenses hurt?

Ortho-k lenses are not meant to hurt, but the rigid lenses can feel annoying or uncomfortable at first. Most people adjust within a few days. If you feel pain during or after wearing the lenses, talk to your eye doctor. [1]

What is the biggest risk of orthokeratology?

Eye infection is the biggest risk of orthokeratology. Washing your hands before touching your eyes and lenses, and cleaning the lenses as your eye doctor instructs, helps prevent it. If you think you have an eye infection, see an eye doctor right away. You may be told to stop wearing the lenses until it clears. [1]

Can orthokeratology slow nearsightedness in children?

Orthokeratology can slow worsening nearsightedness in children. In randomized trials, it reduced eye elongation by 0.18 mm over one year compared with control groups. Eye doctors may suggest ortho-k for children whose vision is getting worse quickly. A child's vision may stabilize, but they may still need some vision correction. [1][2]

What happens if I skip a night of ortho-k?

Skipping ortho-k nights lets your corneas start to rebound to their natural shape, which can blur your vision again. Blurriness can return after just a few missed nights, so treat the lenses as part of your nightly routine. [1]

Do I still need glasses with orthokeratology?

Most people using orthokeratology do not need glasses or contacts during the day once the treatment works. Some children may still need some form of vision correction after their vision stabilizes. Your eye doctor will check your vision at follow-up visits and tell you if you need anything extra. [1]

When should you see an eye doctor right away during ortho-k?

You should see an eye doctor right away during ortho-k if you think you have an eye infection. Also report any change in your vision and any pain during or after wearing the lenses. Your eye doctor may ask you to pause lens wear while an infection is treated. [1]

Who is a good candidate for ortho-k?

Ortho-k suits children and adults with mild to moderate nearsightedness who have healthy eyes. You also need to follow strict lens cleaning and wearing routines.

How should you clean ortho-k lenses?

Wash your hands first and use only the solutions your eye doctor recommends. Never rinse lenses with tap water or saliva, and replace your lens case often.

References

Cleveland Clinic. Orthokeratology (Ortho-K Lenses): What It Is & How It Works. Cleveland Clinic. Last updated July 7, 2026. https://my.clevelandclinic.org/health/treatments/orthokeratology-ortho-k
Lawrenson JG, Huntjens B, Virgili G, et al. Interventions for myopia control in children: a living systematic review and network meta-analysis. Cochrane Database Syst Rev. 2025;2(2):CD014758. PMID 39945354. https://doi.org/10.1002/14651858.CD014758.pub3
Sartor L, Hunter DS, Vo ML, et al. Benefits and risks of orthokeratology treatment: a systematic review and meta-analysis. Int Ophthalmol. 2024;44(1):239. PMID 38904856. https://doi.org/10.1007/s10792-024-03175-w
Liu YM, Xie P. The Safety of Orthokeratology--A Systematic Review. Eye Contact Lens. 2016;42(1):35-42. PMID 26704136. https://doi.org/10.1097/ICL.0000000000000219
Cho P, Tan Q. Myopia and orthokeratology for myopia control. Clin Exp Optom. 2019;102(4):364-377. PMID 30380591. https://doi.org/10.1111/cxo.12839

Medical disclaimer

This article is for general education and does not replace advice from your own eye doctor. Always talk to a qualified eye care professional before starting, changing or stopping any vision treatment, and seek care right away if you suspect an eye infection.