Ortho-K Treatment Process: Assessment & Fitting

EMME Visioncare provides custom-fitted Ortho-K in Singapore at The Cathay and Jelita Mall.

Last reviewed and updated: 30 September 2026

If you are considering Ortho-K for yourself or your child, you may be wondering what actually happens during the treatment process.

Ortho-K is more than simply receiving a pair of overnight contact lenses. The process begins with a detailed eye assessment, followed by precise measurements of the cornea, customised lens design, careful fitting and ongoing follow-up to check vision, lens performance and eye health.

For children using Ortho-K as part of myopia management, monitoring also continues beyond achieving clear daytime vision. Measurements such as axial length help us assess how the child's eyes are growing over time.

Here is what you can generally expect during the Ortho-K treatment process at EMME Visioncare.

Step 1: A comprehensive Ortho-K assessment

The first step is to determine whether Ortho-K is an appropriate option for your eyes.

Your optometrist will consider factors including:

• your current spectacle prescription;
• the amount and type of astigmatism;
• your corneal shape;
• your eye and corneal health;
• your previous contact-lens experience;
• your visual needs and lifestyle; and
• for children, their myopia history and progression.

Ortho-K is not suitable for every person or every prescription, so the purpose of this assessment is not simply to confirm that you are short-sighted. It is to understand whether your eyes are suitable for overnight lens wear and whether Ortho-K is likely to meet your visual or myopia-management needs.

You can learn more about suitability and the overall treatment on our Ortho-K and orthokeratology service page.

Step 2: Mapping the shape of your cornea

One of the most important measurements in Ortho-K fitting is corneal topography.

Corneal topography produces a detailed map of the curvature and shape of the front surface of your eye. Unlike a standard spectacle prescription, which tells us how much optical correction you need, topography shows us the physical shape that the Ortho-K lens needs to work with.

This information is used when designing the customised lens and later becomes an important reference during follow-up visits.

After you begin wearing Ortho-K, new topography maps can be compared with your original measurements. This helps your optometrist evaluate:

• where the treatment zone has formed;
• whether the lens is well centred during sleep;
• how the cornea is responding to treatment; and
• whether the lens design needs refinement.

Good Ortho-K fitting therefore relies on much more than the spectacle prescription alone.

Step 3: Designing your customised Ortho-K lenses

Ortho-K lenses are specially designed rigid gas-permeable contact lenses with a shape that is quite different from an ordinary daytime contact lens.

They use what is known as a reverse-geometry design. Different curves on the back surface of the lens work together with the tear layer between the lens and cornea to produce a controlled, temporary change in the shape of the corneal surface during sleep.

The objective is to create a well-centred treatment effect that provides clear unaided vision when the lenses are removed in the morning.

At EMME Visioncare, digital corneal topography and computer-assisted custom lens design are used to help match the lens to the individual shape of each eye.

This is why Ortho-K should be thought of as a custom fitting process rather than an off-the-shelf contact lens.

Step 4: Checking the Ortho-K lens fit

Once the lenses are available, their fit needs to be assessed on the eye.

Your optometrist may use fluorescein, a temporary diagnostic dye, to examine the pattern of the tear layer underneath the lens.

This allows the practitioner to assess how the different zones of the Ortho-K lens interact with the cornea and whether the lens is positioned appropriately.

A good initial fit does not mean that no further changes will ever be required. The real treatment response becomes clearer after the lenses have been worn overnight and new corneal-topography measurements can be compared with the baseline maps.

Step 5: Learning how to insert, remove and care for the lenses

Before beginning overnight wear, you or your child should be comfortable handling the lenses correctly.

This normally includes learning how to:

• wash and dry your hands properly before handling lenses;
• insert the lenses correctly;
• remove the lenses safely in the morning;
• clean and disinfect them with the recommended system;
• store them correctly;
• recognise a damaged or contaminated lens; and
• know when eye discomfort, redness or other symptoms require professional advice.

Good hygiene is particularly important because Ortho-K lenses are worn overnight.

For practical lens-care instructions, see our Ortho-K lens care and maintenance guide.

Step 6: Your first nights of Ortho-K wear

Ortho-K begins changing the corneal surface relatively quickly.

Many suitable wearers notice an improvement in unaided distance vision after the first night. Further changes often occur during the first several days as the treatment effect develops.

However, the speed of improvement differs between people. Your starting prescription, astigmatism, corneal shape, lens centration and individual response can all influence the timeline.

This is why we avoid promising that every person will achieve a particular amount of vision correction after a fixed number of nights.

If you would like a more detailed explanation of the early treatment timeline, read our guide to how long Ortho-K takes to work.

Step 7: Early follow-up and corneal topography

Follow-up visits are an important part of Ortho-K treatment.

Your optometrist is not only checking whether you can see clearly. Early reviews can help assess:

• your unaided vision;
• any residual prescription;
• the position and size of the treatment zone;
• lens centration;
• corneal topography changes;
• the health of the cornea and surrounding eye tissues;
• comfort during overnight wear; and
• lens handling and hygiene.

If the treatment zone is not developing as intended or vision remains inconsistent, the lens design may need to be reviewed or refined.

The exact follow-up schedule depends on the individual wearer and treatment response, so your optometrist will advise when each review is required.

What does an Ortho-K topography map show?

One of the useful features of corneal topography is that we can compare measurements taken before and after Ortho-K wear.

A difference map shows where the corneal curvature has changed. In a well-centred myopia treatment pattern, there is typically a central treatment area surrounded by a ring of relative steepening.

Your optometrist interprets this pattern together with your vision, refraction, lens fit and eye-health findings.

The colours on a topography map should therefore not be interpreted on their own as a simple measure of whether treatment has “worked”. The clinical meaning depends on the type of map, scale being used and the individual eye.

Ortho-K for children involves more than achieving clear vision

When Ortho-K is prescribed for a child with progressing myopia, there is another important part of the process: long-term myopia monitoring.

Clear daytime vision tells us that the Ortho-K lens is correcting the child's refractive error. It does not, by itself, tell us how quickly the child's eye is continuing to grow.

For this reason, myopia management looks at changes over months and years rather than just the vision measured the morning after wearing the lens.

At EMME Visioncare, axial length is measured as part of our childhood myopia assessment. Axial length measures the distance from the front to the back of the eye and provides an important way of monitoring eye growth.

It is interpreted together with the child's age, prescription, previous progression, eye health and other clinical findings.

You can read more about axial length and why it matters in childhood myopia.

How often should Ortho-K be reviewed?

Ortho-K should not be treated as a lens that is fitted once and then worn indefinitely without professional review.

Regular follow-up allows your optometrist to monitor:

• vision and treatment stability;
• corneal health;
• lens condition;
• lens fit and treatment-zone position;
• cleaning and replacement habits;
• changes in prescription; and
• for children, ongoing myopia progression and eye growth.

The appropriate interval between appointments depends on the wearer, age, clinical findings and stage of treatment.

International clinical guidance for myopia management also emphasises ongoing ocular-health assessment, refraction and, where available, axial-length measurement, with corneal topography being particularly relevant for Ortho-K wearers.

What if the first Ortho-K lens is not perfect?

Ortho-K is a customised fitting process, and sometimes the initial design requires refinement.

This does not necessarily mean the treatment has failed.

Follow-up measurements can show whether the lens is slightly decentered, whether the treatment zone is developing differently from expected or whether residual refractive error remains.

The lens parameters can then be reconsidered using the clinical findings and updated topography.

The goal is not simply to make the corneal map look a particular way. It is to achieve a combination of clear and stable vision, an appropriate lens fit and healthy eyes.

Is Ortho-K treatment permanent?

No. The corneal reshaping produced by Ortho-K is temporary and reversible.

Regular overnight lens wear is generally required to maintain the daytime vision-correction effect. If lens wear is stopped, the cornea gradually moves back towards its original shape and the original refractive error returns.

This is quite different from laser refractive surgery, which permanently alters corneal tissue.

The Ortho-K treatment process at EMME Visioncare

A successful Ortho-K fitting involves much more than selecting a lens based on your spectacle prescription.

The process combines:

• a detailed suitability assessment;
• digital corneal topography;
• customised lens design;
• careful fitting and handling instruction;
• comparison of pre- and post-treatment topography;
• ongoing vision and eye-health reviews; and
• for children undergoing myopia management, monitoring of progression and axial length.

If you are considering overnight lenses, visit our Ortho-K service page to learn more about suitability, benefits, risks and fitting at EMME Visioncare.

If your main concern is a child's increasing short-sightedness, you can also explore our childhood myopia control options and assessment process.

References

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2. Soni PS, Nguyen TT, Bonanno JA. Overnight orthokeratology: visual and corneal changes. Eye & Contact Lens. 2003;29(3):137–145. DOI: 10.1097/01.ICL.0000072831.13880.A0.
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3. Swarbrick HA. Orthokeratology review and update. Clinical and Experimental Optometry. 2006;89(3):124–143. DOI: 10.1111/j.1444-0938.2006.00044.x.
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4. International Myopia Institute. IMI 2025 Digest. Clinical guidance and evidence updates for contemporary myopia management.
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