Who Is Suitable for LASIK? Eligibility, Eye Tests and Reasons You May Not Qualify

Author: Dr Val Phua
Estimated reading time: 17 minutes

LASIK can provide rapid, long-lasting correction of myopia, hyperopia and astigmatism in appropriately selected patients. However, having a prescription that can technically be treated does not automatically mean that LASIK is the safest procedure for that eye.

A suitable LASIK candidate generally has:

An adult, stable prescription
A healthy and regularly shaped cornea
Adequate corneal thickness for the planned treatment
No evidence of keratoconus or corneal instability
A healthy and well-controlled ocular surface
No significant cataract, retinal disease or uncontrolled glaucoma
No active eye infection or inflammation
Realistic expectations about vision, reading glasses and possible side effects
A lifestyle that is compatible with a permanent corneal flap

LASIK suitability is determined from the combination of the prescription, corneal structure, tear-film health, age, general health and visual priorities. No single measurement can confirm that LASIK is safe.

What Is LASIK?

LASIK stands for Laser-Assisted In Situ Keratomileusis.

During modern femtosecond LASIK:

A femtosecond laser creates a thin, hinged corneal flap.
The flap is gently lifted.
An excimer laser removes microscopic amounts of tissue to reshape the underlying cornea.
The flap is repositioned and adheres without stitches.

LASIK permanently changes the corneal shape. It may reduce or eliminate dependence on spectacles and contact lenses, but it does not prevent presbyopia, cataract, glaucoma or future changes in the prescription.

The Typical Suitable LASIK Candidate

A patient is more likely to be suitable when they:

Are at least 18 to 21 years old, depending on the laser platform and regulatory indication
Have had little or no prescription change during the preceding year
Have myopia, hyperopia or regular astigmatism within the laser’s treatment range
Have normal corneal topography and tomography
Have sufficient corneal tissue for both the flap and laser correction
Have no active dry-eye disease, infection or inflammation
Have good vision with appropriate spectacles or contact lenses
Understand that some glasses may still be required
Accept the possibility of glare, halos, dry eye, residual prescription or enhancement
Can attend the required follow-up visits

FDA-approved platforms differ in their age and refractive requirements. For example, one current LASIK platform is labelled for adults aged 18 or older with a change in spherical equivalent no greater than 0.50 D over the previous year, while another is approved from age 22 with similar stability requirements. Approved treatment ranges also differ by device and country.

How Old Must You Be for LASIK?

Minimum Age

LASIK is not normally performed on children.

FDA-approved laser indications generally begin at either:

18 years old, or
21 to 22 years old

depending on the specific laser and treatment profile.

However, reaching the minimum legal or regulatory age does not necessarily mean that the eyes are ready for surgery.

Some people in their late teens and early twenties continue to develop increasing myopia. Operating while the prescription is still progressing may provide an initially good result followed by a later return of short-sightedness.

Is LASIK Suitable at 18?

Possibly, but caution is appropriate.

LASIK at 18 may be reasonable when:

The prescription has remained convincingly stable
The patient is no longer undergoing significant myopic progression
Corneal measurements are normal
There are no ocular-surface or retinal concerns
The expected benefit justifies permanent corneal surgery

It may be preferable to wait when the spectacle prescription has continued to change or when previous records are unavailable.

Is LASIK Suitable After Age 40?

Yes, selected patients over 40 may still be suitable.

A study involving patients aged 40 to 69 found reasonable safety, efficacy and predictability for appropriately selected myopic and hyperopic patients. However, age-related near-vision loss and natural-lens changes become increasingly important.

LASIK does not prevent presbyopia. If both eyes are corrected fully for distance, reading glasses may be needed even when the patient previously read by removing their myopic spectacles. FDA patient information specifically advises that LASIK does not remove the future need for reading glasses.

Possible strategies include:

Correcting both eyes for distance and using reading glasses
Mini-monovision
Blended vision
Leaving one eye mildly myopic for near tasks

A contact-lens simulation is often helpful before permanently creating monovision.

Is LASIK Suitable After Age 50?

Possibly, but the natural lens must be examined carefully.

A patient in their fifties may have:

Early cataract
Presbyopia
A changing prescription caused by the natural lens
Reduced contrast or increasing glare
A shorter interval before cataract surgery becomes necessary

LASIK reshapes the cornea but does not treat an ageing or cloudy natural lens. Where early cataract is already contributing to symptoms, cataract surgery or lens-based correction may be more appropriate.

How Stable Must the Prescription Be?

A stable refraction is one of the most important LASIK requirements.

Many current regulatory indications define stability as no more than approximately 0.50 D of change during the previous 12 months, although the precise definition varies by laser platform.

The surgeon may compare:

Previous spectacle prescriptions
Contact lens prescriptions
Current manifest refraction
Cycloplegic refraction
Measurements from both eyes
Axial length when progressive myopia is suspected

Why Does Stability Matter?

LASIK corrects the prescription present at the time of surgery. It does not stop the eye from continuing to grow or the natural lens from changing.

If myopia is still progressing:

Short-sightedness may return
Glasses may be needed again
An enhancement may be requested
Further laser treatment may not be possible if insufficient corneal tissue remains

What Can Make a Prescription Unstable?

Possible causes include:

Continuing myopia progression
Pregnancy or breastfeeding
Poorly controlled diabetes
Cataract or natural-lens changes
Certain medications
Contact lens-related corneal distortion
Dry-eye-related measurement variability
Accommodation during refraction

The FDA identifies younger age, pregnancy, breastfeeding, diabetes-related changes and medications that alter vision as factors associated with refractive instability.

What Prescriptions Can LASIK Treat?

LASIK can potentially treat:

Myopia
Myopic astigmatism
Hyperopia
Hyperopic astigmatism
Mixed astigmatism

The safe treatment range depends on:

The excimer-laser platform
Local regulatory approval
Corneal thickness
Corneal shape
Optical-zone size
Flap thickness
Pupil size
Predicted residual stromal tissue
The surgeon’s safety criteria

For example, one current FDA-labelled platform includes myopia below −10.00 D, cylinder up to −4.00 D, hyperopia up to +4.00 D and selected mixed astigmatism. Another approved platform has a different myopic and astigmatic range. These numbers are device-specific indications, not universal guarantees of suitability.

Can LASIK Treat High Myopia?

Sometimes.

Higher myopic correction requires greater removal of corneal tissue. This may increase concern about:

Inadequate residual corneal tissue
Corneal ectasia
Refractive regression
Glare or halos
Reduced optical quality
Future enhancement limitations

A patient with −8.00 D may be suitable when the cornea is thick, regular and structurally reassuring, while another patient with −5.00 D may be unsuitable because of abnormal tomography or insufficient tissue.

The degree alone does not determine suitability.

An Implantable Collamer Lens may be preferable when:

The myopia is high or very high
Laser treatment would remove excessive corneal tissue
The cornea is too thin
Preserving the central cornea is a priority
Internal eye anatomy is suitable for ICL implantation

Can LASIK Treat Low Myopia?

Yes, but the expected benefit should still justify the risk.

A patient with a low prescription may obtain good unaided vision from LASIK, but they may already function well with occasional spectacles.

Because LASIK permanently changes a healthy cornea, the decision should consider:

How often glasses are currently required
Contact lens tolerance
Lifestyle inconvenience
Night-driving requirements
Dry-eye risk
Willingness to accept possible side effects

Being technically treatable does not mean that surgery is necessary.

Why Is Corneal Shape Important?

The cornea must be sufficiently regular and structurally stable.

LASIK permanently removes stromal tissue and creates a flap. Performing it on a cornea with an underlying tendency to weaken may contribute to progressive bulging known as corneal ectasia.

Ectasia can cause:

Increasing myopia
Progressive irregular astigmatism
Ghosting
Reduced best-corrected vision
Difficulty obtaining clear vision with ordinary spectacles
Need for rigid or scleral contact lenses
Need for corneal cross-linking
Rarely, corneal transplantation

A validated ectasia-screening study found that risk assessment was improved by considering multiple factors together, including corneal topographic pattern, age, preoperative thickness, degree of myopia and predicted residual stromal-bed thickness. Relying only on one thickness cutoff or one topography flag missed a substantial proportion of the ectasia cases studied.

What Corneal Conditions Make LASIK Unsuitable?

LASIK is generally unsuitable when there is:

Keratoconus
Forme-fruste or suspected keratoconus
Pellucid marginal degeneration
Progressive corneal thinning
Abnormal posterior corneal elevation
Concerning pachymetric progression
Previous corneal ectasia
Significant corneal scarring
Unexplained irregular astigmatism

Current FDA labelling lists keratoconus, corneal ectasia, pellucid marginal degeneration and abnormal corneal topography among conditions in which LASIK should not be performed.

What if There Is a Family History of Keratoconus?

A family history does not automatically rule out surgery, but it should increase the level of caution.

The evaluation may require:

Repeat corneal tomography
Epithelial thickness mapping
Corneal biomechanical assessment
Comparison between the two eyes
Review of old refractions
Assessment for eye rubbing and allergy
Observation over time before deciding

FDA patient information specifically advises patients to disclose a family history of keratoconus, pellucid marginal degeneration or other corneal thinning disorders because apparently normal eyes may have greater susceptibility.

Is Eye Rubbing Relevant?

Habitual vigorous eye rubbing is associated with corneal deformation and is particularly concerning in patients with:

Allergic eye disease
Keratoconus susceptibility
Asymmetric corneal shape
Progressive astigmatism

Active allergy and habitual rubbing should be controlled before elective corneal surgery.

A patient who cannot stop forceful eye rubbing may be a less suitable candidate even when the initial scans appear reassuring.

How Thick Must the Cornea Be?

There is no single corneal thickness that makes every patient safe or unsafe.

The surgeon must consider:

Preoperative corneal thickness
Planned flap thickness
Laser-ablation depth
Optical-zone diameter
Amount of myopia or hyperopia
Residual stromal-bed thickness
Percentage of tissue altered
Corneal tomography
Age and other ectasia risk factors

One current FDA patient booklet lists central corneal thickness below 480 microns as a precaution for that particular platform. Another FDA-approved system contraindicates treatment when the planned procedure would leave less than 250 microns of residual corneal tissue. These are examples of device-specific labelling and should not be treated as universal safety thresholds.

Many surgeons use additional or more conservative safety margins based on the complete corneal assessment.

Can a Thick Cornea Still Be Unsuitable?

Yes.

A thick cornea can still have:

Abnormal tomography
Early keratoconus
Asymmetric curvature
Abnormal posterior elevation
A concerning epithelial pattern
Excessive planned tissue removal
Poor biomechanical behaviour

Thickness cannot compensate for an unstable corneal shape.

Can a Thin Cornea Still Be Treated?

Possibly.

A relatively thin but normally shaped cornea may sometimes be suitable for:

PRK
TransPRK
SMILE
A carefully planned thin-flap LASIK
ICL surgery

The best choice depends on how much tissue each procedure would affect.

A structurally suspicious thin cornea may be unsuitable for all forms of corneal laser correction.

Is LASIK Suitable if You Have Dry Eyes?

Mild, treatable dry eye does not always exclude LASIK, but the ocular surface should be stable before measurements and surgery.

LASIK temporarily disrupts corneal nerves involved in:

Tear production
Blinking
Corneal sensation
Ocular-surface regulation

FDA guidance states that severe dry eye is a contraindication for some LASIK systems and that mild or moderate dry eye can worsen following surgery.

A prospective study found that post-LASIK dry-eye risk was associated with higher preoperative myopia and deeper laser ablation. Another prospective analysis found that many patient-reported symptoms improved by six months, illustrating that the course differs between individuals.

Dry-Eye Conditions That Should Be Treated First

These include:

Meibomian gland dysfunction
Blepharitis
Demodex infestation
Allergic conjunctivitis
Significant corneal staining
Tear-film instability
Aqueous tear deficiency
Contact lens-related inflammation
Incomplete eyelid closure

Treatment may include:

Preservative-free lubricants
Warm compresses and eyelid hygiene
Meibomian gland treatment
Anti-inflammatory medication
Allergy control
Temporary discontinuation of contact lenses
Other targeted dry-eye treatment

The refraction and corneal maps should be repeated after the eye surface has stabilised.

When May Dry Eye Rule Out LASIK?

LASIK may be inappropriate when there is:

Severe aqueous-deficient dry eye
Significant autoimmune-related ocular-surface disease
Persistent corneal staining despite treatment
Severe contact lens intolerance caused by dryness
Reduced corneal sensation
Neuropathic ocular pain
Exposure keratopathy
Unstable measurements caused by the tear film

SMILE, PRK, ICL or continued use of spectacles may sometimes be preferable, but these alternatives have their own risks and do not automatically solve dry-eye disease.

Do Large Pupils Make LASIK Unsuitable?

Not automatically.

Large pupils in dim lighting may increase the likelihood or awareness of:

Halos
Glare
Starbursts
Ghost images
Reduced night-time contrast
Difficulty driving in rain or fog

The effect also depends on:

Optical-zone diameter
Degree of correction
Treatment centration
Pre-existing optical aberrations
Residual prescription
Dry eye
Laser profile

FDA guidance advises measuring pupils under dim-light conditions and counselling patients with large pupils about possible night-vision symptoms.

A large pupil is therefore a counselling and planning factor rather than an automatic disqualification.

Must the Eyes Otherwise Be Healthy?

Yes.

LASIK corrects refractive error. It does not treat diseases of the:

Retina
Macula
Optic nerve
Natural lens
Ocular surface

A patient may have technically successful corneal surgery but remain dissatisfied if another eye condition limits visual potential.

Is LASIK Suitable if You Have Cataract?

Usually not when the cataract is already affecting vision.

Symptoms of early cataract may include:

Glare
Halos
Difficulty driving at night
Reduced contrast
A changing myopic prescription
Reduced best-corrected vision
Colours appearing less vivid

LASIK will not remove the cloudy natural lens.

It can also make future cataract-lens calculations more complex, so patients should tell future cataract surgeons that they have had laser vision correction.

When cataract is the main cause of visual symptoms, cataract surgery is generally more appropriate.

Is LASIK Suitable if You Have Glaucoma?

Uncontrolled glaucoma is a contraindication under current FDA laser labelling. Controlled glaucoma or glaucoma suspicion requires individual assessment.

Important considerations include:

Existing optic nerve damage
Visual-field loss
Eye-pressure control
Corneal thickness
Steroid response
Ability to monitor future progression

LASIK changes corneal thickness and biomechanics, which can make conventional eye-pressure readings lower and more difficult to interpret. Postoperative steroid drops can also raise pressure in susceptible patients.

A patient with moderate or advanced glaucoma may gain little from elective refractive surgery if optic nerve disease already limits vision.

Is LASIK Suitable if You Have Retinal Disease?

Retinal disease does not always make LASIK impossible, but visual potential and long-term risk must be assessed.

Particular attention is needed for patients with:

High myopia
Retinal tears or holes
Previous retinal detachment
Myopic macular degeneration
Diabetic retinopathy
Macular oedema
Epiretinal membrane
Optic nerve disease

LASIK corrects the corneal focusing error but does not shorten an elongated myopic eye or prevent retinal complications.

A dilated retinal examination is often appropriate, particularly in high myopia or when flashes, floaters or peripheral retinal abnormalities are present.

Can LASIK Improve a Lazy Eye?

LASIK does not cure amblyopia.

Amblyopia is reduced visual development in an eye that never achieved normal corrected vision during childhood.

LASIK may reduce the spectacle prescription, but the operated eye generally cannot be expected to see better than its established best-corrected visual potential.

FDA patient information identifies amblyopia as a condition requiring additional caution and counselling.

Is LASIK Suitable if You Have Strabismus?

Possibly, but careful binocular-vision assessment may be required.

Changing the refractive balance between the eyes can occasionally:

Unmask double vision
Disturb a previously compensated eye deviation
Alter accommodation and convergence
Affect monovision tolerance

Patients with previous strabismus, patching, prism glasses or intermittent diplopia should tell the surgeon before treatment. FDA patient information notes that patients with a history of strabismus may have an increased risk of double vision after selected LASIK corrections.

Is LASIK Suitable After a Previous Eye Injury or Operation?

It depends on the nature of the previous problem.

Additional caution may be needed after:

Previous LASIK or PRK
Radial keratotomy
Corneal cross-linking
Corneal transplantation
Significant corneal injury
Herpes keratitis
Retinal surgery
Glaucoma surgery
Cataract surgery

The remaining corneal thickness, shape, scarring and visual potential must be reassessed.

Previous refractive surgery is not an automatic indication for further LASIK. FDA guidance advises individual evaluation because another procedure may not be recommended.

Is LASIK Suitable After Herpes Eye Infection?

A previous herpes simplex or herpes zoster eye infection requires significant caution.

Laser surgery may reactivate ocular herpes, and previous infection may have caused:

Corneal scarring
Reduced corneal sensation
Irregular astigmatism
Impaired healing
Recurrent inflammation

Recent herpes infection or corneal damage from previous ocular herpes is listed as a contraindication in current FDA patient labelling, while a more remote history remains a warning requiring individual assessment.

Can Someone With Diabetes Have LASIK?

Uncontrolled diabetes is a contraindication because:

The prescription may fluctuate
Healing may be delayed
Infection risk may be greater
Dry eye may be more significant
Diabetic retinopathy or macular disease may limit vision

Current FDA labelling distinguishes uncontrolled diabetes from selected controlled diabetes, but advises that even well-controlled patients may have less predictable healing.

Some clinical series have reported acceptable outcomes in carefully selected patients with well-controlled diabetes, while other studies have found increased epithelial complications. This supports an individual rather than automatic approach.

A potential candidate with diabetes should generally have:

Stable blood glucose control
A stable refraction
No significant diabetic retinopathy
No diabetic macular oedema
A healthy ocular surface
No significant corneal neuropathy
No major systemic complications affecting healing

Can Someone With an Autoimmune Disease Have LASIK?

Active autoimmune or connective-tissue disease is a contraindication under current FDA labelling because of concerns about healing and corneal damage. Controlled disease requires careful case-by-case consideration.

Conditions that may be relevant include:

Rheumatoid arthritis
Systemic lupus erythematosus
Sjögren syndrome
Inflammatory bowel disease
Psoriatic disease
Other connective-tissue disorders

Important considerations include:

Disease activity
Ocular involvement
Dry-eye severity
Immunosuppressive medication
Corneal sensation
Previous inflammatory episodes
The treating physician’s assessment

Selected patients with stable, controlled systemic disease have undergone LASIK successfully in published clinical series, but these results should not be generalised to active disease or significant ocular-surface involvement.

What Medications May Affect LASIK Suitability?

The surgeon should be told about all prescription, over-the-counter and recreational medications.

Potentially relevant medicines include:

Isotretinoin
Systemic steroids
Chemotherapy
Immunosuppressants
Medications that worsen dryness
Drugs that alter refraction or accommodation
Medication associated with poor wound healing

Current FDA patient information specifically highlights isotretinoin, steroids, chemotherapy and other treatments that may affect dryness, immunity or healing.

Medication should not be stopped without agreement from the prescribing doctor.

Can LASIK Be Performed During Pregnancy or Breastfeeding?

LASIK is generally postponed during pregnancy and breastfeeding.

Hormonal and fluid changes may cause temporary changes in:

Refraction
Corneal thickness
Corneal curvature
Tear-film function
Contact lens tolerance

Current FDA patient labelling lists pregnancy and nursing among situations in which LASIK should not be performed because the cornea and prescription may change temporarily.

Surgery should be reconsidered after:

Pregnancy has ended
Breastfeeding has stopped
Hormonal changes have settled
The prescription has again demonstrated stability

Is LASIK Suitable for Contact-Sport Athletes?

Possibly, but the permanent flap must be considered.

Activities with repeated risk of direct eye trauma include:

Boxing
Martial arts
Rugby
Football
Water polo
Wrestling
Military training
Police or security work

The LASIK flap becomes stable for normal daily life, but severe trauma can disturb it even after the early healing period.

FDA guidance specifically advises patients who participate in contact sports to discuss the increased flap-injury risk.

SMILE or PRK may be preferable when avoiding a hinged flap is a major priority.

Can Pilots, Divers or Military Personnel Have LASIK?

Possibly, but occupational requirements vary.

Before surgery, patients should check the requirements of:

Civil aviation authorities
Military services
Police forces
Diving organisations
Transport or commercial-driving employers
Other occupations with mandated visual standards

The FDA checklist advises patients to confirm whether their career restricts refractive surgery.

The appropriate procedure may also depend on:

Night-vision standards
Glare tolerance
Trauma exposure
Recovery time
Documentation requirements

Are Realistic Expectations Part of Suitability?

Yes.

A technically excellent candidate may still be unsuitable if their expectations cannot be met.

LASIK aims to reduce dependence on glasses. It does not guarantee:

Perfect vision in every environment
Better-than-glasses vision
No glare or halos
No dry eye
Permanent spectacle independence
No need for reading glasses
No future enhancement
Protection against cataract or retinal disease

The PROWL studies found high overall satisfaction after LASIK, but some patients developed new halos, glare, starbursts, double images or dry-eye symptoms. Dissatisfaction was uncommon, yet the findings support detailed preoperative counselling rather than treating LASIK as risk-free.

What Visual Result Should a Patient Expect?

The likely postoperative result depends partly on the patient’s preoperative best-corrected vision.

LASIK cannot overcome vision limited by:

Amblyopia
Retinal disease
Macular degeneration
Optic nerve damage
Corneal scarring
Cataract
Irregular astigmatism

The realistic aim is generally to obtain unaided vision that approaches the quality previously achieved with spectacles or contact lenses.

A small residual prescription may remain, and glasses may still be useful for:

Night driving
Fine distance detail
Reading
Prolonged computer work
Future prescription changes

What Tests Are Needed Before LASIK?

A complete assessment is more extensive than checking the spectacle prescription.

Refraction and Visual Acuity

The surgeon measures:

Unaided vision
Current spectacle correction
Manifest refraction
Best-corrected visual acuity
Prescription stability

Cycloplegic Refraction

Cycloplegic drops temporarily relax the eye’s focusing muscles.

This can help identify:

Over-minus prescriptions
Latent hyperopia
Accommodation-related variability
A difference between manifest and cycloplegic measurements

Large differences between dilated and undilated refractions may reduce predictability and require further assessment.

Corneal Topography

Topography maps the curvature of the front corneal surface.

It helps assess:

Regularity
Astigmatism
Asymmetry
Contact lens warpage
Possible keratoconus

Corneal Tomography

Tomography evaluates the cornea in three dimensions, including:

Anterior elevation
Posterior elevation
Corneal thickness distribution
Pachymetric progression
The position of the thinnest point

Modern imaging has improved detection of subtle corneal abnormalities, but screening is not infallible. Post-LASIK ectasia has occasionally occurred despite apparently low preoperative risk, reinforcing the importance of combining multiple measurements and clinical judgement.

Corneal Thickness and Tissue Calculations

The surgeon calculates:

Expected flap thickness
Expected ablation depth
Residual stromal-bed thickness
Total percentage of tissue affected
Whether an adequate structural safety margin remains

Epithelial Thickness Mapping

The epithelium can partly mask an irregular underlying stromal shape.

Mapping may help identify:

Early keratoconus patterns
Contact lens warpage
Localised epithelial compensation
Previous surgical changes

Corneal Biomechanical Assessment

Some clinics use devices that assess how the cornea deforms under an air impulse.

These measurements may add information about ectasia susceptibility, but no biomechanical test can guarantee that ectasia will never occur.

Dry-Eye and Eyelid Assessment

The examination may include:

Tear-film break-up time
Corneal and conjunctival staining
Tear meniscus
Meibomian gland assessment
Eyelid margin examination
Tear production
Symptom questionnaires

The FDA checklist and current patient labelling emphasise that dry eye should be assessed before treatment.

Pupil Measurement

Pupil size should be assessed under appropriately dim conditions when night vision is relevant.

Eye-Pressure and Optic-Nerve Assessment

The surgeon checks for:

Ocular hypertension
Glaucoma
Suspicious optic nerves
Previous steroid response

Baseline measurements should be retained because LASIK may affect the interpretation of future pressure readings.

Natural-Lens Examination

The natural lens is examined for:

Cataract
Early nuclear change
Causes of changing refraction
Causes of glare or reduced contrast

Dilated Retinal Examination

A retinal examination may identify:

Retinal holes
Retinal tears
Lattice degeneration
Macular disease
Other conditions limiting visual potential

This is especially important in moderate or high myopia.

Why Must Contact Lenses Be Stopped Before the Assessment?

Contact lenses can temporarily alter:

Corneal curvature
Tear-film quality
Astigmatism
Corneal topography
Refraction

The FDA recommends discontinuing contact lenses for an appropriate period before the LASIK examination and surgery.

The required interval depends on:

Soft or rigid lens type
Toric lens use
Overnight wear
Duration of contact lens use
Evidence of corneal warpage
Stability of repeated measurements

Measurements may need to be repeated if the corneal shape continues to change after the lenses are stopped.

Who Is Definitely Not Suitable for LASIK?

LASIK is generally inappropriate when there is:

Keratoconus or another corneal ectatic disorder
A cornea too thin for the proposed treatment
Severe dry-eye disease
Active corneal infection
Active keratitis, iritis or uveitis
Recent ocular herpes infection or significant herpes-related corneal damage
Active autoimmune or connective-tissue disease
Uncontrolled diabetes
Uncontrolled glaucoma
Pregnancy or breastfeeding
A prescription that is still changing
Inadequate residual corneal tissue after the planned treatment

These contraindications are reflected in current FDA laser labelling, although precise criteria differ by device.

Who Requires Extra Caution?

Individualised evaluation is required when there is:

Mild or moderate dry eye
Controlled diabetes
Controlled autoimmune disease
Controlled glaucoma or glaucoma suspicion
A history of ocular herpes
A family history of keratoconus
Borderline corneal thickness
Large pupils
Significant contact-sport exposure
Previous eye surgery
Strabismus
Amblyopia
High myopia
Reduced vision that glasses do not fully correct
A strong tendency to form abnormal scars
Medications that affect healing

A warning or precaution does not automatically mean that surgery is impossible. It means that the expected benefit must be weighed more carefully against the additional risk.

What if You Are Not Suitable for LASIK?

Being unsuitable for LASIK does not necessarily mean that all refractive surgery is impossible.

SMILE

SMILE may be considered when:

Myopia or myopic astigmatism is within the treatment range
Avoiding a flap is important
Contact-sport participation is relevant
The cornea is otherwise structurally suitable
Early dry-eye disruption is a concern

SMILE still removes corneal stromal tissue and is not suitable for unstable or ectatic corneas.

PRK or TransPRK

PRK may be considered when:

Avoiding a flap is important
The cornea is relatively thin but otherwise healthy
Surface treatment leaves a safer structural margin
Contact or combat sports are relevant
The patient accepts more discomfort and slower recovery

PRK still carries risks of haze, infection, regression and ectasia.

Implantable Collamer Lens

ICL may be considered when:

Myopia is high
Corneal tissue is insufficient
Preserving the cornea is important
Corneal laser surgery is unsuitable
The internal eye anatomy is appropriate

ICL avoids corneal ablation but introduces intraocular risks involving vault, eye pressure, cataract, endothelial cells and infection.

Cataract Surgery

Cataract surgery may be more appropriate when:

The natural lens is already cloudy
Glare or reduced contrast is caused by cataract
The prescription is changing because of the lens
The patient is older and lens-based correction provides a more logical long-term solution

Spectacles or Contact Lenses

These remain appropriate and safe options for many patients.

Elective refractive surgery is not necessary simply because it is technically available.

Frequently Asked Questions About LASIK Suitability

Am I Suitable for LASIK if My Prescription Is High?

Possibly.

The corneal shape, thickness and calculated tissue removal are more important than the prescription alone. ICL may be preferable if laser treatment would remove excessive tissue.

Am I Suitable if My Cornea Is Thin?

Possibly, but LASIK may not be the safest procedure.

PRK, SMILE or ICL may be considered depending on tomography and tissue calculations. A thin, abnormal cornea may be unsuitable for every corneal laser procedure.

Can I Have LASIK With Dry Eyes?

Mild, treatable dry eye may be stabilised before surgery.

Severe or persistent dry eye can make LASIK unsuitable.

Can I Have LASIK if I Cannot Tolerate Contact Lenses?

It depends on why the contact lenses are intolerable.

Intolerance caused by convenience or lens fit may not be a problem. Intolerance caused by severe dry eye, allergy or corneal inflammation requires treatment and may increase surgical risk.

Can I Have LASIK if I Am 18?

Possibly, but only when the prescription is convincingly stable and the eyes are otherwise suitable.

Waiting may be safer when myopia is still progressing.

Can I Have LASIK After 40?

Yes, but LASIK does not prevent presbyopia.

Reading glasses or a monovision strategy may be needed.

Can I Have LASIK After 50?

Selected patients can, but early cataract and natural-lens changes must be excluded.

Can LASIK Correct Astigmatism?

Yes, LASIK can correct regular astigmatism within the treatment range of the laser platform.

Irregular astigmatism may indicate corneal disease and may not be suitable.

Can LASIK Correct Hyperopia?

Yes, selected hyperopic patients can be treated.

Hyperopic suitability depends on corneal dimensions, centration, age and the amount of correction required.

Can I Have LASIK With Keratoconus?

Routine LASIK is contraindicated in keratoconus because it can worsen corneal instability.

Can I Have LASIK After Corneal Cross-Linking?

Possibly in very selected stable cases, but routine LASIK may not be appropriate.

Alternative surface or lens-based strategies may be considered after careful specialist assessment.

Can I Have LASIK With Glaucoma?

Uncontrolled glaucoma is unsuitable.

Controlled glaucoma or glaucoma suspicion requires careful assessment because postoperative pressure monitoring becomes more complex.

Can I Have LASIK With Diabetes?

Possibly when diabetes is well controlled, the refraction is stable and there is no significant retinopathy, neuropathy or healing concern.

Uncontrolled diabetes is unsuitable.

Can I Have LASIK With an Autoimmune Disease?

Active autoimmune disease is unsuitable.

Stable controlled disease may occasionally be considered after consultation with the treating specialist, but significant dry eye or systemic treatment may still rule it out.

Can I Have LASIK During Pregnancy?

No. Surgery should generally be postponed until pregnancy and breastfeeding are over and the refraction has restabilised.

Can I Have LASIK if I Play Contact Sports?

Possibly, but flap trauma must be considered.

SMILE or PRK may offer a better structural match for patients with repeated impact risk.

Does LASIK Guarantee 6/6 Vision?

No.

The outcome depends on the eye’s preoperative visual potential, measurements, healing and residual prescription.

Will I Never Need Glasses Again?

Not necessarily.

Glasses may still be required for reading, night driving, residual refractive error or future changes.

Can LASIK Be Reversed?

No.

The corneal tissue removed by the excimer laser cannot be replaced.

Does Passing a Basic Screening Mean LASIK Is Safe?

Not necessarily.

A thorough evaluation should assess corneal shape, thickness, tissue calculations, ocular surface, pupil size, natural lens, eye pressure and retinal health.

Key Takeaway

A suitable LASIK candidate is not simply someone who is short-sighted and does not like wearing glasses.

Good candidates generally have:

A stable adult prescription
A healthy, regularly shaped cornea
Adequate corneal tissue
No evidence of keratoconus or ectasia susceptibility
A stable ocular surface
No significant cataract or uncontrolled eye disease
No active infection or inflammation
Realistic expectations
A lifestyle compatible with a permanent flap

Important reasons to postpone or avoid LASIK include:

Progressive prescription change
Keratoconus or abnormal tomography
Insufficient corneal tissue
Severe dry eye
Active eye disease
Uncontrolled diabetes or glaucoma
Active autoimmune disease
Pregnancy or breastfeeding
Significant cataract
Expectations that surgery cannot realistically meet

Suitability should be determined from a comprehensive examination rather than an online degree or corneal-thickness cutoff.

For some patients, LASIK provides the best combination of rapid recovery, accurate correction and convenience.

For others, SMILE, PRK, ICL, cataract surgery, spectacles or contact lenses provide a safer balance of benefits and risks.

References

US Food and Drug Administration. ZEISS MEL 90 LASIK Patient Information Booklet. Updated 2024.
US Food and Drug Administration. LASIK Surgery Checklist.
US Food and Drug Administration. When Is LASIK Not for Me?
US Food and Drug Administration. TECHNOLAS TENEO 317 Model 2: Summary of Safety and Effectiveness Data. 2023.
Randleman JB, Trattler WB, Stulting RD. Validation of the Ectasia Risk Score System for Preoperative LASIK Screening. American Journal of Ophthalmology. 2008;145:813–818. PMID: 18328998.
El-Naggar MT, et al. Assessment of Preoperative Risk Factors for Post-LASIK Ectasia Development. 2023. PMID: 38073674.
De Paiva CS, Chen Z, Koch DD, et al. The Incidence and Risk Factors for Developing Dry Eye After Myopic LASIK. American Journal of Ophthalmology. 2006;141:438–445. PMID: 16490488.
Rush SW, et al. Patient-Reported Dry Eye Outcomes After Myopic Femtosecond LASIK: A Six-Month Prospective Analysis. 2023. PMID: 37521150.
Eydelman M, Hilmantel G, Tarver ME, et al. Symptoms and Satisfaction of Patients in the Patient-Reported Outcomes With LASIK Studies. JAMA Ophthalmology. 2017;135:13–22. PMID: 27893066.
Ghanem RC, de la Cruz J, Tobaigy FM, Ang LPK, Azar DT. LASIK in the Presbyopic Age Group: Safety, Efficacy and Predictability in Patients Aged 40 to 69 Years. 2007. PMID: 17382397.
Halkiadakis I, Belfair N, Gimbel HV. LASIK in Patients With Well-Controlled Diabetes. 2005. PMID: 16338557.
Fraunfelder FW, Rich LF. LASIK Complications in Diabetes Mellitus. 2002. PMID: 11917170.
Cobo-Soriano R, Beltrán J, Baviera J. LASIK Outcomes in Patients With Underlying Systemic Contraindications. 2006. PMID: 16647130.
Garcia-Gonzalez M, et al. Effect of Age on Visual and Refractive Results After LASIK. 2019.
Alió JL, Muftuoglu O, Ortiz D, et al. A 10-Year Prospective Audit of LASIK Outcomes for Myopia. 2010. PMID: 20153899.