Orthokeratology (Ortho-K): How Overnight Contact Lenses Help Slow Childhood Myopia

Author: Dr Val Phua
Estimated reading time: 25 minutes

Orthokeratology, commonly called Ortho-K, uses specially designed rigid contact lenses worn while a child sleeps.

During the night, the lenses temporarily reshape the front surface of the cornea.

When the lenses are removed in the morning, many children can see clearly during the day without:

Spectacles
Daytime contact lenses
Laser eye surgery

Orthokeratology also provides a recognised form of childhood myopia control.

It can slow the rate at which the eye becomes longer, reducing the amount of additional myopia that develops during childhood.

In the two-year ROMIO randomised clinical trial, children wearing Ortho-K lenses had average axial elongation of 0.36 mm, compared with 0.63 mm among children wearing ordinary single-vision spectacles. This represented approximately 43% slower average eye growth in that study.

More recent evidence supports a similar overall conclusion. A 2026 systematic review of prospective trials found that Ortho-K reduced axial elongation by approximately 0.15 mm during the first year, with a benefit that remained evident in studies extending to two or three years. The exact treatment response varied considerably among children and studies.

Orthokeratology has two separate effects:

It temporarily corrects the child’s existing myopia by changing corneal shape.
It slows further axial elongation through optical signals created by the reshaped cornea.

These effects should not be confused.

Ortho-K does not:

Permanently cure myopia
Permanently flatten the cornea
Shorten an elongated eye
Guarantee spectacle-free vision throughout every day
Stop myopia completely in every child
Eliminate the future retinal risks associated with myopia
Remove the need for regular eye examinations

The corneal reshaping effect is reversible.

When the child stops wearing the lenses, the cornea gradually returns towards its original shape and the original distance blur returns.

The myopia-control benefit is also present only while appropriate treatment continues. Research following children who discontinued Ortho-K found that axial elongation accelerated after stopping and slowed again after treatment resumed.

Ortho-K can be effective, but it requires a greater commitment than spectacles.

Because the lenses are worn overnight, parents and children must follow strict rules regarding:

Hand washing
Lens cleaning
Lens-case replacement
Avoidance of tap water
Follow-up examinations
Prompt management of redness, pain or blurred vision

Microbial keratitis is uncommon, but it can threaten sight and leave a permanent corneal scar.

A 2025 multicentre study involving 7,415 patient-years of Ortho-K wear estimated an incidence of approximately 5.4 cases of microbial keratitis per 10,000 patient-years. Singapore case reports have also documented infectious keratitis and residual corneal scarring in children wearing overnight Ortho-K lenses.

The central message for parents is:

Orthokeratology can provide clear daytime vision and meaningful myopia control, but it is a medical contact-lens treatment rather than a simple pair of overnight glasses. Its success depends on appropriate child selection, accurate fitting, strict hygiene, parental supervision and regular review.

The Quick Answer

What Is Orthokeratology?

Orthokeratology uses reverse-geometry rigid gas-permeable contact lenses worn during sleep.

The lenses temporarily alter the shape of the corneal epithelium so that light is focused more accurately on the retina after the lenses are removed.

Does Ortho-K Slow Childhood Myopia?

Yes.

Randomised trials and meta-analyses show that Ortho-K slows average axial elongation compared with ordinary single-vision spectacles.

A meta-analysis of seven randomised trials found average reductions in axial elongation of approximately:

0.11 mm at six months
0.16 mm at twelve months
0.23 mm at eighteen months
0.28 mm at twenty-four months

compared with control treatment. The estimated relative control effect declined over time, illustrating that Ortho-K usually slows rather than completely stops eye growth.

Will My Child See Clearly Without Glasses?

Many appropriately selected children achieve useful unaided daytime vision.

The quality and duration of clear vision depend on:

Baseline myopia
Astigmatism
Corneal shape
Lens fit
Overnight wearing time
Treatment-zone position
Pupil size
Tear film
Individual response

Some children may still need:

Low-powered spectacles late in the day
Spectacles during the initial fitting period
Glasses if a lens is missed
Residual correction for high myopia or astigmatism

Does Ortho-K Permanently Correct Myopia?

No.

The cornea gradually returns towards its original shape after lens wear stops.

The child’s previous distance blur then returns.

At What Age Can a Child Start?

There is no single minimum age that suits every child.

Clinical trials have included children from approximately six years of age.

Suitability depends more on:

The child’s myopia and progression risk
Corneal measurements
Ocular-surface health
Ability to cooperate
Parental supervision
Hygiene
Reliability with follow-up

Younger children may have more to gain because they frequently progress faster and have more remaining years of eye growth. In the ROMIO trial, the youngest control children progressed particularly quickly, while the difference between Ortho-K and ordinary spectacles was most marked in this age group.

How Long Must the Lenses Be Worn Each Night?

Most children wear the lenses during a full night’s sleep.

A typical target is approximately:

Seven to nine hours
Every night
According to the prescribed schedule

Some children maintain adequate vision with occasional reduced-frequency wear after stabilisation, but irregular use can cause:

Fluctuating daytime vision
Incomplete correction
Decentred treatment
Greater difficulty assessing progression

The wearing schedule should be changed only after review.

Is Ortho-K Safe?

It can be used safely when:

The child is appropriately selected.
The lenses fit correctly.
Hygiene is excellent.
Tap water is avoided.
Follow-up is regular.
Lenses are stopped immediately if symptoms develop.

Minor corneal staining is relatively common. More serious infection is uncommon but potentially sight-threatening. A pooled analysis of prospective childhood studies found that most Ortho-K adverse events were corneal abrasions or staining, while serious complications remained much less frequent.

Understanding Childhood Myopia

Why Does Myopia Cause Blurred Distance Vision?

In most children with progressive myopia, the eye becomes longer than its ideal optical length.

Light from distant objects then focuses in front of the retina instead of directly on it.

This causes blurred distance vision.

What Is Axial Length?

Axial length is the distance from the front of the cornea to the back of the eye.

It is commonly measured in millimetres.

Increasing axial length is associated with increasing structural myopia.

Why Should Eye Growth Be Slowed?

As the eye elongates, the tissues at the back of the eye are stretched over a larger internal surface.

Higher myopia and longer axial length are associated with increased lifetime risks of:

Retinal tears
Retinal detachment
Myopic macular degeneration
Myopic choroidal neovascularisation
Myopic traction maculopathy
Glaucoma
Cataract

Myopia control therefore has a long-term health objective.

It is not simply intended to reduce spectacle thickness.

Why Is Early Treatment Important?

Children who become myopic at a young age have more years during which the eye may continue elongating.

Younger children also tend to progress faster.

Treatment may therefore be considered soon after true myopia is confirmed rather than waiting until the prescription becomes high.

How Orthokeratology Reshapes the Cornea

What Is a Reverse-Geometry Lens?

An Ortho-K lens differs from an ordinary rigid contact lens.

Its back surface contains several zones with different curves.

These commonly include:

A central treatment curve
A steeper reverse curve
Alignment curves
A peripheral edge-lift system

Together, these curves create a controlled tear layer and position the lens over the cornea during sleep.

Does the Lens Press the Cornea Flat?

The effect is more subtle than simply pressing on the eye.

The combination of:

Lens geometry
Tear-film forces
Eyelid pressure
Redistribution of corneal epithelial cells

produces central corneal flattening and relative mid-peripheral steepening.

The deeper corneal layers are not surgically removed.

Which Part of the Cornea Changes?

The main change occurs within the corneal epithelium, the outermost cellular layer of the cornea.

This helps explain why the refractive effect is:

Rapid
Reversible
Dependent on continued lens wear

What Happens to the Centre of the Cornea?

The central corneal surface becomes flatter.

A flatter cornea has less focusing power.

This reduces the eye’s myopic refractive error and improves unaided distance vision.

What Happens Around the Treatment Zone?

A ring of relative corneal steepening develops around the central flattened area.

This ring changes how light reaches the peripheral retina and is thought to contribute to the myopia-control effect.

How Quickly Does the Cornea Change?

Some improvement may be evident after the first night.

The full effect usually develops progressively over:

Several nights
One to two weeks
Occasionally longer for higher prescriptions or complex corneas

During this period, vision may fluctuate.

How Does Ortho-K Slow Eye Growth?

The mechanism is not completely understood.

Several optical changes may contribute.

Peripheral Myopic Defocus

Ordinary spectacles correct central vision but may allow light in parts of the peripheral retina to focus behind the retinal surface.

This is called relative peripheral hyperopic defocus.

Ortho-K reshaping creates a ring of additional positive corneal power around the central treatment zone.

This can move part of the peripheral image forward, producing relative peripheral myopic defocus.

The retina may interpret this as a signal to reduce further eye growth.

Newer wide-angle retinal-refraction research has confirmed that Ortho-K produces peripheral myopic-defocus patterns and that the position and width of these patterns are associated with axial elongation.

Higher-Order Aberrations

Ortho-K increases certain higher-order optical aberrations, particularly:

Positive spherical aberration
Coma
Other multifocal optical effects

These changes may contribute to the growth-control signal.

A two-year study found that larger increases in total higher-order and spherical aberrations were associated with slower axial elongation among children receiving Ortho-K treatment.

Treatment-Zone Size

The central flattened region is called the treatment zone.

Research suggests that a smaller treatment zone may bring the ring of relative corneal power closer to the pupil, increasing the treatment signal reaching the retina.

A randomised two-year study found that lenses with a smaller back optic-zone diameter created a smaller treatment zone and reduced axial elongation by approximately 0.22 mm more than conventional lenses.

A 2026 meta-analysis similarly found less axial elongation with smaller optic-zone designs than with conventional Ortho-K designs, although these lenses also produced more higher-order aberrations.

Treatment-Zone Decentration

A mild degree of treatment-zone decentration may alter the distribution of myopic defocus.

Several retrospective studies have found an association between greater decentration and slower axial elongation.

This does not mean that a poorly centred lens is desirable.

Excessive decentration can cause:

Ghost images
Glare
Halos
Irregular astigmatism
Reduced visual quality
Corneal staining
Unstable lens position

The clinical objective remains a safe, stable fit with useful vision.

Pupil Size

A larger pupil may allow more of the peripheral treatment ring to enter the visual system.

This may partly explain why some children respond better than others.

However, larger pupils may also increase:

Night glare
Halos
Ghost images
Reduced contrast

Pupil size is only one of many factors affecting response.

How Effective Is Orthokeratology?

The ROMIO Trial

The ROMIO trial randomly assigned children aged six to ten years to:

Ortho-K lenses
Ordinary single-vision spectacles

After two years, average axial elongation was:

0.36 mm with Ortho-K
0.63 mm with spectacles

This represented approximately 43% slower average elongation.

What Do Meta-Analyses Show?

A 2023 meta-analysis of randomised trials estimated approximately 0.28 mm less axial elongation after two years with Ortho-K than with control treatment.

A 2026 analysis of fifteen prospective trials found an average difference of approximately:

0.15 mm at one year
0.19 mm in studies extending for at least two years

The studies showed substantial variation, and most participants were from East Asian populations.

Why Do Treatment Results Differ?

Response varies because of differences in:

Age
Baseline myopia
Axial length
Corneal shape
Pupil size
Lens design
Treatment-zone size
Wearing time
Centration
Parental myopia
Outdoor exposure
Individual retinal and scleral biology

Does Ortho-K Stop Myopia Completely?

Usually not.

Many successfully treated eyes continue to elongate, but more slowly than expected without treatment.

A child may still progress despite:

Clear daytime vision
Good lens fit
Excellent adherence

The treatment should therefore be judged by axial length, not by unaided vision alone.

Does Better Daytime Vision Mean Better Myopia Control?

Not necessarily.

Clear daytime vision confirms that the cornea has been reshaped effectively.

It does not prove that axial elongation is adequately controlled.

A child can have excellent unaided vision while the eye continues to grow.

Does Ortho-K Work Better in Younger Children?

Younger children often have a larger absolute benefit because their untreated progression is faster.

They may also require:

Closer monitoring
Stronger parental involvement
Earlier consideration of combination treatment

Does Ortho-K Work for Every Prescription?

No.

Standard Ortho-K is most commonly used for low to moderate myopia.

The exact treatment range depends on:

Lens design
Corneal curvature
Corneal diameter
Astigmatism
Pupil size
Practitioner experience
Desired daytime visual acuity

Orthokeratology for High Myopia

Can High Myopia Be Treated?

Complete correction becomes more difficult as myopia increases.

Greater corneal flattening may produce:

Smaller treatment zones
More irregularity
More glare
Less predictable vision
Greater corneal staining

What Is Partial-Reduction Ortho-K?

In partial-reduction treatment, the lens corrects part of the myopia.

The remaining prescription is corrected during the day with spectacles.

A two-year randomised trial in children with high myopia found average axial elongation of:

0.19 mm with partial-reduction Ortho-K
0.51 mm with single-vision spectacles

This demonstrated that Ortho-K may still provide a myopia-control signal even when it cannot fully correct the child’s prescription. However, completion numbers in the trial were relatively small.

Does High Myopia Require Retinal Examination?

Yes.

Children with high myopia may require:

Dilated retinal examination
Review of flashes and floaters
Assessment of corrected vision
Consideration of inherited or structural causes
Continued monitoring into adulthood

Ortho-K does not remove the structural risks associated with a long eye.

Orthokeratology and Astigmatism

Can Ortho-K Correct Astigmatism?

It can correct selected amounts of regular astigmatism.

Success depends on whether the astigmatism arises mainly from:

Corneal shape
Internal optics
Both

What Is Toric Orthokeratology?

Toric Ortho-K lenses have different alignment characteristics in different corneal meridians.

They may improve:

Lens centration
Stability
Astigmatism correction
Treatment-zone shape

Does Toric Ortho-K Control Myopia?

The TO-SEE study followed children with moderate-to-high astigmatism.

After two years, average axial elongation was:

0.31 mm with toric Ortho-K
0.64 mm in the spectacle control group

This represented approximately 52% slower average elongation. The study was not randomised, so the result should be interpreted accordingly.

When Is Astigmatism Unsuitable?

Extra caution is required when there is:

Irregular astigmatism
Keratoconus
Corneal scarring
Progressive astigmatism
Marked asymmetry
Abnormal corneal tomography

Corneal topography or tomography should be reviewed before fitting.

Who May Be a Good Candidate?

Ortho-K may suit a child who:

Has confirmed progressive myopia
Wants clear unaided daytime vision
Participates in sport
Can tolerate rigid lenses
Has suitable corneal topography
Has a healthy ocular surface
Has reliable parental supervision
Can attend regular follow-up
Will comply with hygiene instructions

Younger Children

Young children can use Ortho-K successfully when a parent takes responsibility for:

Cleaning
Disinfection
Lens inspection
Insertion or supervision
Removal
Appointment attendance
Recognising warning symptoms

The child’s chronological age alone is not enough to determine suitability.

Children Who Play Sport

Ortho-K can be convenient for:

Tennis
Football
Basketball
Gymnastics
Running
Dance
Other activities where glasses are inconvenient

Protective sports eyewear may still be required for injury prevention.

Children Who Swim

The lenses are removed during the day, which avoids daytime contact-lens wear in the pool.

The child should never:

Swim in the Ortho-K lenses
Shower in the lenses
Rinse the lenses with tap water
Store lenses in water

Prescription swimming goggles may still be useful if residual blur remains.

Who May Not Be Suitable?

Ortho-K may be unsuitable or require postponement when the child has:

Active eye infection
Significant dry eye
Severe blepharitis
Poorly controlled allergic conjunctivitis
Frequent vigorous eye rubbing
Recurrent corneal inflammation
Corneal scarring
Keratoconus or suspicious tomography
Reduced corneal sensation
Poor hygiene
Unreliable follow-up
Inability to report pain or visual change
Unrealistic expectations
A prescription outside a safe treatment range

Eye Allergy

Allergic conjunctivitis is common in children.

It may cause:

Itching
Eye rubbing
Mucus
Redness
Lens deposits
Poor lens tolerance

Allergy should be controlled before and during Ortho-K treatment.

A one-year safety study found that allergic conjunctivitis was associated with a greater risk of corneal adverse events among paediatric Ortho-K wearers.

Dry Eye and Tear-Film Problems

Children with poor tear quality may experience:

Lens binding
Fluctuating vision
Corneal staining
Discomfort
Difficulty removing lenses

A 2025 prospective study found relatively small average changes in tear-film measures after six months, but significantly higher corneal-staining scores in Ortho-K wearers than spectacle wearers.

Poor Hygiene

Ortho-K should not be prescribed when the family cannot reliably follow contact-lens care.

The benefit of myopia control does not justify unsafe overnight lens wear.

What Happens During an Ortho-K Assessment?

Medical and Eye History

The clinician may ask about:

Age at myopia onset
Previous prescriptions
Rate of progression
Family history
Eye allergy
Eye rubbing
Dry-eye symptoms
Previous infection
Contact-lens experience
General health
Medication
Sleep schedule
Sport and swimming
Hygiene routines

Visual Acuity and Refraction

Testing may include:

Unaided visual acuity
Corrected visual acuity
Cycloplegic refraction
Subjective refraction
Astigmatism assessment

Cycloplegic refraction is particularly important in younger children and when the prescription is inconsistent.

Axial Length

A baseline axial-length measurement helps:

Estimate risk
Document structural progression
Monitor treatment
Distinguish corneal correction from actual eye growth

Slit-Lamp Examination

The eyelids, conjunctiva, tear film and cornea are examined for:

Allergy
Blepharitis
Staining
Scarring
Inflammation
Infection
Lens-wear suitability

Corneal Topography

Corneal topography maps the shape of the cornea.

It is essential for:

Selecting the initial lens
Assessing corneal symmetry
Detecting suspicious ectasia
Evaluating astigmatism
Checking treatment-zone size
Checking treatment-zone centration
Monitoring the fit

Pupil Measurement

Pupil size may influence:

Night vision
Halos
Treatment-zone coverage
Myopia-control response

Retinal Examination

A dilated examination may be appropriate when:

Myopia is high
Corrected vision is reduced
Flashes or floaters are present
There is a family history of retinal disease
The child has another ocular condition

How Are the Lenses Fitted?

Trial Lens or Computer-Based Design

The initial design may be selected using:

Corneal topography
Keratometry
Corneal diameter
Eccentricity
Refraction
Pupil size
Manufacturer software

Fluorescein Assessment

A fluorescent dye may be used to examine the tear pattern beneath the lens.

The clinician evaluates:

Centration
Movement
Central alignment
Reverse-zone filling
Edge lift
Lens binding risk

First Overnight Wear

Many practices review the child after the first night.

The appointment may assess:

Unaided vision
Corneal staining
Topography
Treatment-zone position
Lens fit
Comfort
Handling
Early complications

Early Follow-Up

A typical early schedule may include review:

After the first night
At approximately one week
At approximately one month
At intervals thereafter

The exact schedule depends on:

Lens design
Clinical findings
Progress
Child age
Risk factors

Ongoing Follow-Up

After stabilisation, reviews may occur every:

Three months
Six months
According to the clinician’s protocol

Active myopia-control monitoring commonly includes axial-length assessment approximately every six months.

What Happens During the First Few Nights?

Day One

The child may notice:

Better distance vision
Remaining blur
Halos
Fluctuation
Mild lens awareness during insertion

First Week

Vision commonly improves progressively.

Some children may need temporary spectacles for:

School
Evening activities
Residual astigmatism
Unequal correction between the eyes

First Month

The treatment pattern usually becomes more stable.

The final lens may still require adjustment when there is:

Decentration
Incomplete correction
Staining
Poor comfort
Lens binding
Excessive movement

Does Wearing the Lens Hurt?

A rigid lens is more noticeable than a soft contact lens when the eyes are open.

Because Ortho-K is worn during sleep, many children tolerate the lenses well once their eyes are closed.

Persistent pain is not normal.

Daytime Vision with Ortho-K

How Long Does Clear Vision Last?

After successful treatment, useful vision may last throughout the day.

Some children notice increasing blur:

Late in the evening
After a short night’s sleep
When a lens was missed
When lenses are old or damaged
When myopia has progressed
When the fit has changed

Why Does Vision Sometimes Fluctuate?

Possible causes include:

Incomplete corneal reshaping
Lens decentration
Dry eye
Unequal sleep duration
Lens deposits
Corneal staining
Progressing axial myopia
Warped or damaged lenses

Halos and Glare

Ortho-K may increase:

Halos around lights
Glare
Ghost images
Starbursts
Reduced contrast in dim light

Symptoms may be more noticeable when:

The pupil is large.
The treatment zone is small.
The lens is decentered.
Baseline myopia is high.
The child has residual astigmatism.

These optical effects are related partly to the same higher-order aberrations that may contribute to myopia control.

Can the Child Drive Later as a Teenager?

Older teenagers should have adequate unaided or corrected vision for the applicable driving standard.

A backup pair of spectacles should be available because vision may fluctuate if:

A lens is lost
A lens is not worn
Treatment is interrupted
Corneal reshaping becomes uneven

Lens Handling

Insertion

A typical sequence includes:

Wash hands thoroughly.
Dry them with a clean, lint-free towel.
Inspect the lens.
Place the lens on a clean fingertip or insertion tool.
Add the recommended sterile solution if advised.
Hold the eyelids securely.
Place the lens gently onto the centre of the eye.
Check that vision and comfort are as expected.

The exact technique should follow the clinician’s instructions.

Removal

Removal may involve:

Eyelid manipulation
A sterile suction remover
Lubricating drops
Specific lens-release techniques

A bound lens should not be forcibly pulled from a dry cornea.

Who Should Handle the Lenses?

This depends on the child.

For younger children, parents should often:

Insert the lenses
Remove the lenses
Clean them
Inspect them
Replace the solution
Monitor symptoms

Older children may gradually take over, but supervision should continue until safe habits are reliable.

Hygiene: The Most Important Safety Rules

Wash and Dry Hands

Hands should be washed with soap and dried thoroughly before:

Touching the lenses
Touching the eyes
Handling the lens case

Wet hands increase the risk of water-related contamination.

Never Use Tap Water

Tap water should not be used to:

Rinse lenses
Rinse the lens case
Store lenses
Wet insertion devices
Remove cleaning solution
Lubricate the eye

Tap water may contain organisms capable of causing severe keratitis.

A 2026 case-control study found that cleaning Ortho-K lenses with tap water was associated with a markedly increased risk of Acanthamoeba keratitis. Other identified risk behaviours included failing to rub the lenses, delayed case replacement, poor supervision and irregular follow-up.

Rub and Rinse as Directed

Even when a solution is labelled “no rub”, mechanical rubbing may help remove:

Deposits
Biofilm
Microorganisms
Mucus
Tear proteins

Follow the prescribed care system.

Use Fresh Solution

Never:

Top up old solution
Reuse yesterday’s solution
Transfer solution into an unlabelled bottle
Use expired solution
Mix incompatible products

Replace the Lens Case

The lens case should be replaced regularly according to professional advice and product instructions.

Delayed case replacement has been associated with increased risk of Acanthamoeba keratitis in paediatric Ortho-K users.

Keep the Case Clean and Dry

After disinfection:

Empty the case.
Clean it using the recommended method.
Allow it to air-dry in a clean environment.
Avoid bathroom surfaces and splashing water.

No Sleeping in a Damaged Lens

Inspect each lens for:

Chips
Cracks
Scratches
Warping
Deposits
Discolouration

A damaged lens should not be worn.

No Swimming or Showering in the Lenses

Water exposure increases the risk of infection.

Remove Ortho-K lenses before:

Showering
Bathing
Swimming
Water sports

Avoid Lens Wear When Unwell

Contact the clinic for advice when the child has:

A red eye
Eye pain
Significant discharge
Light sensitivity
Reduced vision
Severe cold or flu symptoms affecting hygiene
Inability to handle the lenses safely

Backup Spectacles

Every Ortho-K child should have a current pair of spectacles available.

They may be needed when:

A lens is lost
A lens breaks
The eye is irritated
Treatment is paused
The child is travelling
Infection is suspected

Risks and Side Effects

Corneal Staining

Small areas of epithelial staining are among the most common findings.

Possible causes include:

Lens binding
Poor tear film
Deposits
Excessive bearing
Decentration
Inadequate cleaning
Damaged lenses

Most mild staining resolves after:

Temporary discontinuation
Lens adjustment
Improved lubrication
Better cleaning
Treating allergy or blepharitis

A pooled prospective safety analysis found that corneal abrasion or staining accounted for approximately 40% of reported adverse events.

Lens Binding

A lens may adhere tightly to the cornea in the morning.

The child should not remove it forcefully.

Management may involve:

Lubricating drops
Blinking
Gentle lens-release techniques
Changes to lens fit
Treatment of dry eye

Corneal Infiltrates

Inflammatory white cells may accumulate within the cornea.

Symptoms may include:

Redness
Discomfort
Light sensitivity
Tearing
Reduced vision

Contact-lens wear should stop and the eye should be examined.

Microbial Keratitis

Microbial keratitis is an infection of the cornea.

Possible organisms include:

Pseudomonas
Acanthamoeba
Other bacteria
Fungi

Symptoms include:

Increasing pain
Redness
Light sensitivity
Tearing
Discharge
Reduced vision
A white corneal spot

This is an emergency.

How Common Is Microbial Keratitis?

Different studies report slightly different rates.

A 2025 Japanese multicentre study found four cases during 7,415 patient-years, corresponding to approximately 5.4 cases per 10,000 patient-years.

A study of children in Russia estimated approximately 4.9 to 5.3 cases per 10,000 patient-years.

Earlier research produced less precise estimates with wider confidence intervals.

The absolute risk is low, but the potential consequence is serious.

Can Infection Leave a Scar?

Yes.

A central or paracentral corneal scar may cause:

Permanent blur
Glare
Irregular astigmatism
Reduced best-corrected vision

A Singapore series described five children with Pseudomonas keratitis associated with overnight Ortho-K; all retained a residual central or paracentral scar after the infection resolved.

Allergic Conjunctivitis

Allergy may cause:

Itching
Redness
Mucus
Eye rubbing
Lens deposits
Poor centration

Treatment may need to be paused during a significant flare.

Dryness

Dryness may produce:

Lens discomfort
Binding
Fluctuating vision
Staining

Ocular-surface treatment should be individualised.

Corneal Warpage

Ortho-K intentionally changes corneal shape.

This means that corneal measurements may not represent the untreated cornea while therapy is active.

The child or future adult should always tell an eye-care professional about past Ortho-K before:

Refractive-surgery assessment
Cataract calculations
Corneal-topography interpretation
Keratoconus evaluation

Does Ortho-K Thin the Cornea?

The central epithelial profile changes.

Research has not shown progressive destructive thinning of a healthy cornea from correctly managed Ortho-K.

However, corneal integrity must still be checked regularly.

Does Ortho-K Cause Keratoconus?

Ortho-K has not been established as a cause of keratoconus.

It should not be used on a cornea already showing:

Keratoconus
Ectasia
Suspicious asymmetry
Progressive thinning

Because Ortho-K changes topography, baseline maps are important.

Ortho-K and Low-Dose Atropine

Why Combine Treatments?

Ortho-K provides an optical myopia-control signal.

Atropine provides a pharmacological signal.

Combining them may be considered when:

The child is very young
Myopia started early
Progression was rapid before treatment
Axial elongation remains excessive
The child has a strong family history
The projected risk of high myopia is substantial

Does the Combination Work Better?

Several randomised studies show an additional average effect.

In the two-year AOK trial, axial elongation was:

0.17 mm with Ortho-K plus 0.01% atropine
0.34 mm with Ortho-K alone

Photophobia occurred more often in the combined-treatment group.

A separate two-year Japanese trial found axial elongation of:

0.29 mm with combination treatment
0.40 mm with Ortho-K alone

The additional effect was clearer among children with lower baseline myopia.

A multicentre randomised trial published in 2026 also found significantly less two-year axial elongation with Ortho-K plus 0.01% atropine than with Ortho-K alone, although the absolute difference was smaller than in some earlier studies.

Is Combination Treatment Necessary for Every Child?

No.

Many children respond adequately to Ortho-K alone.

Combination treatment adds:

Medication
Cost
Light sensitivity
Pupil dilation
Treatment complexity
Additional monitoring

It should be used for a clinical reason.

Why May Atropine Help Ortho-K More in Low Myopia?

In lower myopia, conventional Ortho-K produces:

Less corneal flattening
A weaker mid-peripheral power ring
Less change in higher-order aberrations

Atropine may therefore provide a larger additional effect.

This remains an area of active research.

What if Ortho-K Is Not Working Well Enough?

Confirm Adherence

Ask:

Are the lenses worn every night?
Is sleep duration adequate?
Are nights frequently missed?
Is one lens removed during sleep?
Are the lenses inserted correctly?

Check Lens Condition

Inspect for:

Deposits
Warping
Chips
Scratches
Incorrect lens identification
Age-related deterioration

Check Corneal Topography

Assess:

Treatment-zone size
Centration
Symmetry
Corneal staining
Residual astigmatism
Whether the lens design remains appropriate

Confirm Axial-Length Measurement

A single change should be interpreted carefully.

Axial measurements may vary with:

Instrument
Fixation
Time of day
Choroidal thickness
Data quality

A trend across repeated visits is more reliable.

Consider Lens Modification

Possible changes include:

Smaller optic-zone diameter
Different alignment curve
Different compression factor
Toric periphery
Alternative lens design

Modified lens designs may increase the myopia-control effect but can also increase aberrations or affect night vision.

Add Atropine

Low-concentration atropine may be considered when control remains inadequate.

Change Treatment

Alternatives include:

Myopia-control spectacles
Dual-focus soft contact lenses
Atropine with spectacles
Another combination

The child should not remain on an ineffective or poorly tolerated treatment simply because significant money has already been spent.

Ortho-K Versus Other Myopia-Control Options

Ortho-K Versus Myopia-Control Spectacles

Advantages of Ortho-K

Clear unaided daytime vision
Convenient for sport
Established myopia-control evidence
Treatment does not depend on wearing spectacles during the day
Can be combined with atropine

Advantages of Myopia-Control Spectacles

No contact with the cornea
No overnight infection risk
Easier for young children
Less demanding hygiene
Suitable for many levels of astigmatism

The average treatment effects overlap.

The safest practical treatment is often the one that the child will use consistently.

Ortho-K Versus Atropine

Advantages of Ortho-K

Corrects daytime vision
No daily daytime spectacles for many children
Avoids pharmacological light sensitivity

Advantages of Atropine

No contact-lens handling
No corneal infection risk
Can be used with almost any spectacle prescription
May suit irregular routines

Atropine does not correct the child’s vision and must be combined with appropriate glasses or contact lenses.

Ortho-K Versus Dual-Focus Soft Contact Lenses

Advantages of Ortho-K

No daytime lens wear
No daytime dryness from a contact lens
Clear unaided vision for many children
Parent can supervise lens handling at home

Advantages of Daily Disposable Soft Lenses

No overnight lens wear
A fresh lens each day
Less complex cleaning
More familiar soft-lens comfort

Both require mature contact-lens hygiene.

Which Is Best?

There is no universal winner.

Treatment selection depends on:

Age
Prescription
Astigmatism
Corneal shape
Progression rate
Pupil size
Allergy
Dry eye
Sport
Hygiene
Family preference
Cost
Treatment response

What Happens If Treatment Stops?

Vision After Stopping

The central cornea gradually steepens towards its original shape.

The child’s unaided distance vision becomes blurrier.

How Long Does Reversal Take?

The main refractive effect may regress over:

Days
One to several weeks
Longer after high corrections or prolonged wear

The time varies between children.

Does Myopia Progress Faster After Stopping?

Research suggests that axial elongation can accelerate after discontinuation, particularly when Ortho-K is stopped at a young age.

In the DOEE study, children who stopped Ortho-K at or before fourteen years experienced faster axial elongation during the discontinuation phase. Growth slowed again after Ortho-K was resumed.

Is This a True Rebound?

The observed acceleration may represent:

Return to the child’s untreated growth rate
A temporary rebound
A combination of both

The evidence is less extensive than the rebound literature for atropine.

Should Treatment Be Tapered?

There is no universally established tapering schedule.

Some children may transition to:

Alternate-night wear
Myopia-control spectacles
Dual-focus contact lenses
Atropine
A combination

Treatment changes should be monitored using axial length.

When Can Ortho-K Stop?

Factors include:

Age
Pubertal stage
Recent axial growth
Recent refraction
Age at myopia onset
Family history
Previous rapid progression
Treatment tolerance
Alternative correction

One stable six-month period does not prove that eye growth has finished.

Long-Term Wear

Long-term observational research suggests that Ortho-K can continue to provide useful refractive correction over many years, with corneal staining remaining the most frequent complication and serious infection remaining uncommon.

Long-term users still require regular review because:

The child grows.
Corneal shape changes.
Lenses age.
Hygiene habits may deteriorate.
Myopia progression may continue.
Allergy or dry eye may develop.

Lens Replacement

The replacement interval depends on:

Material
Scratching
Warpage
Deposits
Lens fit
Prescription
Manufacturer guidance
Clinical condition

Lenses should not be retained indefinitely simply because they still feel comfortable.

Travelling with Ortho-K

Families should carry:

Current spectacles
Spare lenses when available
Care solution
Lens case
Suction remover if used
Lubricating drops
Clinic contact details
A copy of the lens prescription or parameters

Do not transfer lens solution into unlabelled containers.

Air Travel

The child can generally travel with Ortho-K supplies.

During a flight:

Keep lenses and solution in hand luggage.
Avoid handling lenses with unwashed hands.
Do not use aircraft tap water.
Wear backup spectacles when lens care cannot be performed safely.

School Camps and Sleepovers

Consider whether:

A responsible adult can supervise.
Clean hand-washing facilities are available.
The child can handle lenses independently.
Tap-water avoidance is practical.
Backup spectacles are available.

It may be safer to pause Ortho-K and use spectacles during some camps.

Common Myths

“Ortho-K Permanently Cures Myopia”

False.

The corneal reshaping effect is temporary.

“The Lens Stops the Eye from Growing”

Not completely.

It slows average axial elongation.

“Clear Daytime Vision Means the Myopia Is No Longer Progressing”

False.

Axial length must still be monitored.

“The Lens Pushes the Whole Eye Back into Shape”

False.

It modifies the front corneal epithelium.

It does not shorten the eyeball.

“A Child Can Use Any Overnight Rigid Lens”

False.

Ortho-K lenses require specialised design and fitting.

“The Stronger the Corneal Flattening, the Better the Myopia Control”

Not necessarily.

Excessive treatment may reduce visual quality and increase complications.

“A Decentred Lens Works Better”

Not a safe general conclusion.

Although research has found associations between some decentration and slower axial elongation, excessive decentration may cause visual disturbance and corneal problems.

“Ortho-K Is Risk-Free Because It Is Reversible”

False.

The optical effect is reversible, but an infection may leave permanent scarring.

“Children Cannot Handle Rigid Lenses”

Many can, especially with parental help.

“Tap Water Is Safe Because It Is Safe to Drink”

False.

Drinking-water standards do not make tap water sterile enough for contact-lens care.

“Saline Disinfects the Lens”

Ordinary saline rinses but may not disinfect.

Use the prescribed disinfecting system.

“A Lens Case Can Be Used Until It Breaks”

False.

Cases should be replaced regularly.

“The Child Can Continue Wearing the Lens Through Mild Redness”

False.

Redness may be the first sign of inflammation or infection.

“The Child Should Wear the Lenses Longer When Vision Is Blurry”

Not without professional advice.

Blur may result from a poor fit, deposits or corneal injury.

“Ortho-K Removes Retinal-Detachment Risk”

False.

A structurally long eye remains myopic even when unaided vision is clear.

“Ortho-K Means Outdoor Time Is No Longer Important”

False.

Outdoor activity remains advisable for general health and a healthy visual environment.

“Ortho-K Is Always Stronger Than Myopia-Control Glasses”

False.

Results vary by lens design and child.

Frequently Asked Questions

Can a Six-Year-Old Use Ortho-K?

Potentially, with careful selection and strong parental supervision.

Is There a Maximum Age?

No strict maximum age exists.

The myopia-control benefit is most relevant while the eye is still progressing.

Adults may use Ortho-K for daytime refractive correction.

Can Ortho-K Be Used in Only One Eye?

Yes, when clinically appropriate.

Possible situations include:

Anisometropia
One myopic eye
Different correction needs

Both eyes still require monitoring.

Can My Child Sleep Face-Down?

Sleep position can influence lens position in some children.

The clinician may ask about sleep habits if topography shows repeated decentration.

What if My Child Sleeps Only Six Hours?

The correction may be incomplete or wear off earlier.

The result depends on:

Baseline myopia
Lens design
Corneal response
Treatment stability

What if One Night Is Missed?

Vision may remain reasonably clear after an established treatment pattern, but some blur may return.

Use backup spectacles when needed.

Can the Child Nap in the Lenses?

Only if specifically advised.

Additional wear is not automatically beneficial.

Can the Child Wear the Lenses While Awake?

They may be worn briefly during insertion or before sleep, but prolonged awake wear is not usually the treatment objective.

Can the Lenses Get Lost Behind the Eye?

No.

The conjunctival tissues prevent a contact lens from travelling behind the eyeball.

It may move under an eyelid and require assistance to remove.

Can a Lens Break in the Eye?

Rigid lenses can chip or crack, but this is uncommon during normal wear.

A damaged lens should not be inserted.

Are Ortho-K Lenses Hard?

They are rigid gas-permeable lenses.

“Rigid” describes the material’s shape stability, not an inability to transmit oxygen.

Do They Allow Oxygen Through?

Modern Ortho-K lenses are made from oxygen-permeable materials suitable for prescribed overnight use.

This does not remove infection or hypoxia risk if the lenses are misused.

Can Ortho-K Cause Dry Eye?

It may contribute to dryness, staining or lens binding in some children.

Can It Treat Hyperopia?

Specialised corneal-reshaping designs exist for other refractive errors, but childhood myopia-control Ortho-K usually refers to myopic correction.

Can It Correct Presbyopia?

Not relevant to childhood myopia treatment.

Will My Child Still Need Glasses?

Possibly.

Glasses may be required:

During initial treatment
Late in the day
After missed nights
For residual high myopia
For residual astigmatism
If treatment is paused

Can Ortho-K Be Combined with Glasses?

Yes.

Partial-reduction Ortho-K uses spectacles for the residual daytime prescription.

Can It Be Combined with Atropine?

Yes, in selected children.

How Often Should Axial Length Be Measured?

Approximately every six months is commonly used during active myopia control.

What if Axial Length Still Increases?

Some increase is expected.

The clinician considers:

Age
Pretreatment progression
Amount of elongation
Lens adherence
Lens design
Corneal topography
Other risk factors

What if Axial Length Appears to Decrease?

Small apparent reductions may reflect:

Measurement variability
Choroidal thickening
Time-of-day effects
Instrument differences

They do not usually mean that the eye has permanently shortened.

Can Ortho-K Be Used After Atropine?

Yes.

Can the Child Change from Defocus Glasses to Ortho-K?

Yes, after a suitable assessment.

Does Ortho-K Affect Future LASIK or SMILE?

It does not automatically prevent future refractive surgery.

The lenses must be stopped long enough for corneal shape to stabilise before assessment.

How Long Must Ortho-K Be Stopped Before Laser Assessment?

The required washout varies.

It depends on:

Duration of previous wear
Prescription
Corneal stability
Topography

Repeated measurements are needed rather than relying on one fixed number of days.

Does Ortho-K Affect Cataract Calculations Later in Life?

The cornea generally returns towards baseline after cessation.

The future cataract surgeon should nevertheless be told about previous Ortho-K wear, particularly if the corneal shape remains unusual.

Can Ortho-K Prevent Retinal Detachment?

It cannot guarantee prevention.

Slowing axial elongation may reduce future risk compared with allowing greater myopia progression.

Is Ortho-K Worth the Cost?

Its value depends on:

Treatment success
Child preference
Convenience
Safety
Family resources
Alternative options

The decision should not be based solely on achieving spectacle-free daytime vision.

Warning Signs Requiring Urgent Assessment

The lenses should be removed immediately and not reinserted when the child develops:

Eye pain
Increasing redness
Light sensitivity
Reduced vision
Persistent tearing
Discharge
A white spot on the cornea
Significant foreign-body sensation
Difficulty opening the eye

Prompt examination is required.

Do not:

Wait for the next routine appointment
Restart the lens when symptoms temporarily improve
Use leftover antibiotic or steroid drops without advice
Patch the eye
Rinse the lens or eye with tap water

A contact-lens-related corneal infection may progress rapidly.

A Parent’s Ortho-K Checklist

Before Starting

Has true myopia been confirmed?
Was cycloplegic refraction performed when appropriate?
Is axial length documented?
Is corneal topography normal?
Is the child’s ocular surface healthy?
Is allergy controlled?
Is there significant eye rubbing?
Is the child’s prescription within a reasonable range?
Can the family attend frequent early reviews?
Can a parent supervise lens care?

Lens-Care Readiness

Can hands be washed and dried properly?
Does the family understand that tap water is prohibited?
Is the prescribed care solution available?
Can the lenses be rubbed and rinsed correctly?
Will fresh solution be used every day?
Will the case be replaced regularly?
Are backup spectacles available?

Each Night

Are the eyes white and comfortable?
Are the lenses clean and intact?
Have hands been washed and dried?
Is the correct lens going into each eye?
Is the child free from significant pain or redness?

Each Morning

Does the child see clearly?
Is either eye red?
Is there pain or light sensitivity?
Is a lens bound?
Is there discharge?
Is one eye seeing less clearly?

Follow-Up

Is unaided vision stable?
Is axial length being measured?
Is the treatment zone centred?
Is there corneal staining?
Are the lenses scratched or deposited?
Is the child missing nights?
Is allergy controlled?
Is atropine needed?
Should the lens design be adjusted?

Questions to Ask the Eye-Care Professional

Is my child suitable for Ortho-K?
What degree of correction is expected?
Will residual glasses be required?
How much axial elongation has occurred?
What lens design is being used?
Is the treatment zone appropriately positioned?
What is the expected adaptation period?
Which cleaning system should be used?
How frequently should the case be replaced?
What should we do after a missed night?
What symptoms require immediate review?
When should atropine be added?
How will we decide when to stop treatment?

The Bottom Line

Orthokeratology uses specially designed rigid gas-permeable contact lenses worn during sleep.

The lenses temporarily reshape the corneal epithelium, producing:

Central corneal flattening
Clearer unaided daytime vision
A surrounding ring of altered corneal power
Optical signals that can slow axial elongation

Randomised trials and meta-analyses show that Ortho-K can reduce average childhood axial elongation compared with ordinary spectacles.

The two-year ROMIO trial found approximately 43% slower average axial elongation with Ortho-K.

More recent evidence suggests an average reduction of approximately 0.15 mm during the first year, with benefits continuing in longer studies.

The treatment does not:

Permanently cure myopia
Permanently reshape the cornea
Shorten the eye
Guarantee complete control
Remove the need for retinal monitoring

Its benefits include:

Clear unaided daytime vision
Convenience during sport
Meaningful myopia control
Reversibility of the corneal effect
Ability to combine treatment with atropine

Its limitations include:

Overnight contact-lens wear
Frequent early reviews
Need for strict hygiene
Vision fluctuation
Halos and glare
Corneal staining
Rare but potentially sight-threatening microbial keratitis

The greatest preventable risks are related to poor lens care.

Families must:

Wash and dry their hands
Keep lenses away from tap water
Rub and disinfect lenses properly
Use fresh solution
Replace the case regularly
Attend follow-up visits
Stop the lenses immediately for pain, redness, light sensitivity or reduced vision

Combination treatment with low-concentration atropine may provide additional control in selected young or fast-progressing children, but is not necessary for everyone.

The most important message is:

Ortho-K is an effective and practical myopia-control option for carefully selected children, but it should be treated as a supervised medical contact-lens therapy. Clear daytime vision is only one outcome—the child’s corneal health, hygiene and axial-length progression must remain central throughout treatment.

References

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