Can Thin Corneas Still Qualify for ICL Surgery in Korea?

Having thin corneas can make patients nervous when they are considering vision correction surgery. Many people who have been told that their corneas are too thin for LASIK or another laser procedure immediately wonder whether they have any surgical options left.

One option that may be worth discussing is ICL, or Implantable Collamer Lens surgery.

Unlike LASIK and SMILE Pro, ICL does not correct myopia by removing corneal tissue. Instead, an implantable lens is placed inside the eye while the natural crystalline lens remains in place. This fundamental difference means that corneal thickness is evaluated differently for ICL than for corneal laser procedures.

However, thin corneas do not automatically mean that you qualify for ICL. The procedure has its own anatomical requirements, and the health and structure of the eye must be carefully evaluated before surgery.

For patients considering ICL in Korea, understanding the difference between corneal thickness and ICL candidacy can help you prepare for a more informed ophthalmology consultation.

What Is ICL Surgery?

How ICL Corrects Myopia

ICL stands for Implantable Collamer Lens. It is a phakic intraocular lens designed to correct certain levels of myopia, with toric versions available for selected patients with myopic astigmatism.

During ICL surgery, the lens is positioned inside the eye behind the iris and in front of the natural crystalline lens. The natural lens is not removed.

Instead of changing the shape of the cornea, the implanted lens changes how incoming light is focused onto the retina.

This is one of the main differences between ICL and procedures such as LASIK or SMILE Pro.

Why Corneal Thickness Is Different for ICL

Laser vision correction depends on the cornea because corneal tissue is reshaped during treatment.

ICL works differently.

Because the refractive correction comes from an implanted lens rather than intentional corneal tissue removal, a patient with relatively thin corneas may still be evaluated for ICL.

This does not mean that corneal thickness becomes irrelevant. Your ophthalmologist still needs to assess the overall health of the cornea and the rest of the eye.

Can Thin Corneas Still Qualify for ICL?

Thin Corneas Do Not Automatically Disqualify You

In general, having thin corneas does not by itself rule out ICL.

This is one reason ICL can be discussed with patients who have previously been told that they are poor candidates for LASIK because of corneal thickness or other corneal characteristics.

The important distinction is that ICL has different anatomical requirements.

Instead of asking only, "How thick is my cornea?" the ophthalmologist needs to ask whether the eye has enough appropriate space for the implant and whether the cornea and internal structures are healthy enough for the procedure.

Other Measurements Become Especially Important

Before ICL, your ophthalmologist may evaluate:

• Anterior chamber depth
• Anterior chamber angle
• Endothelial cell density
• Corneal health
• Eye pressure
• Prescription stability
• Retinal health
• Overall ocular health
• Pupil characteristics
• Previous eye surgery or disease

These measurements help determine whether an ICL can be positioned safely and whether the potential benefits outweigh the risks.

Why ICL May Be Considered When LASIK Is Not Suitable

LASIK and ICL Use Different Correction Methods

LASIK reshapes the cornea by removing and repositioning corneal tissue.

The amount of tissue that needs to be treated depends partly on the patient's prescription. Higher prescriptions can require greater amounts of tissue removal.

If a patient has a relatively thin cornea, the surgeon may have concerns about whether sufficient tissue can safely remain after laser treatment.

ICL does not require this type of corneal reshaping.

That is why a patient who is not considered suitable for LASIK because of corneal parameters may still be evaluated for ICL.

SMILE Pro Also Depends on Corneal Anatomy

SMILE Pro is another corneal refractive procedure.

It uses a femtosecond laser to create a lenticule inside the cornea, which is then removed through a small incision. The removal of this tissue changes the cornea's focusing power.

Consequently, corneal thickness and shape remain important parts of SMILE Pro candidacy.

A Korean ophthalmology study published in 2025, for example, used specific corneal thickness and residual stromal bed requirements for its laser-treated group, while its ICL group was evaluated using internal eye measurements such as anterior chamber depth and endothelial cell density.

What Eye Measurements Matter for ICL?

Anterior Chamber Depth

One of the most important measurements for ICL is anterior chamber depth, or ACD.

This measurement helps determine whether there is adequate space within the front portion of the eye for the implant.

For the EVO ICL indication described in current U.S. FDA labeling, anterior chamber depth must be at least 3.00 mm when measured from the corneal endothelium to the anterior surface of the natural lens.

The exact criteria used in Korea can depend on the specific lens model, local regulatory requirements, and the treating ophthalmologist's clinical assessment.

A patient with thin corneas but adequate internal eye dimensions may therefore still be considered for ICL.

Anterior Chamber Angle

The angle between the iris and cornea is also important.

Current FDA labeling excludes eyes with an anterior chamber angle below Grade III by gonioscopy.

This is another reason that a standard glasses prescription or corneal thickness measurement cannot determine ICL eligibility on its own.

Why Endothelial Cell Density Matters

What Are Corneal Endothelial Cells?

The corneal endothelium is a thin layer of cells on the inner surface of the cornea.

These cells help maintain the cornea's fluid balance and transparency.

Because an ICL sits inside the eye, maintaining healthy endothelial cells is an important part of long-term eye health.

Your ophthalmologist may therefore perform specular microscopy or another endothelial assessment before recommending surgery.

Low Endothelial Cell Density Can Affect Candidacy

A patient may have a relatively thin cornea but excellent endothelial cell health.

Another patient may have normal corneal thickness but insufficient endothelial cell density.

These two situations have different implications.

Current EVO ICL labeling requires a minimum endothelial cell density based on factors such as age and anterior chamber depth. Patients below the applicable minimum may face a higher risk of corneal complications.

Therefore, "thin cornea" should never be used as the only factor when deciding whether ICL is appropriate.

Can High Myopia and Thin Corneas Be Treated With ICL?

Why This Combination May Lead to an ICL Evaluation

High myopia can make corneal laser surgery more challenging because more refractive correction may require more corneal tissue treatment.

When high myopia is combined with a relatively thin cornea, an ophthalmologist may consider whether ICL offers a better anatomical approach.

ICL can correct higher levels of myopia within the available lens indications without reshaping the central cornea.

Current FDA-approved EVO ICL labeling covers selected levels of myopia up to -20.00 D for reduction of myopia, subject to specific requirements.

However, the presence of high myopia means that retinal health should also be assessed carefully.

High Myopia Requires a Broader Eye Examination

High myopia is not simply a strong glasses prescription.

Highly myopic eyes can have structural changes involving the retina and other parts of the eye.

Before elective refractive surgery, your ophthalmologist may therefore perform a dilated retinal examination and evaluate the overall condition of the eye.

If a retinal problem is identified, it may need to be addressed or monitored before refractive surgery is considered.

What If You Were Told You Are "Too Thin" for LASIK?

Ask What Measurement Was the Concern

Being told that you are not suitable for LASIK does not necessarily mean that you are not suitable for every type of vision correction.

Ask your eye surgeon what specifically caused the concern.

It could be:

• Central corneal thickness
• Corneal shape
• Suspected keratoconus
• Estimated residual stromal bed
• High prescription
• Ocular surface problems
• Another aspect of your eye health

Understanding the reason can help determine which alternatives should be investigated.

ICL Is Not Automatically the Next Step

It is important not to assume:

"Too thin for LASIK = ICL candidate."

That is not medically accurate.

ICL requires appropriate internal eye anatomy and a healthy ocular environment.

For example, insufficient anterior chamber depth, inadequate endothelial cell density, glaucoma, certain forms of inflammation, cataract, or other eye conditions can make ICL unsuitable.

Thin Corneas: ICL vs SMILE Pro

How the Two Procedures Differ

FactorICLSMILE ProMain approachImplantable lensCorneal laser procedureCentral corneal tissue removalNoYesNatural lensPreservedPreservedIntraocular surgeryYesNoCorneal thickness importanceNot used to calculate corneal tissue removal in the same wayImportantInternal eye anatomyVery importantLess central to candidacyEndothelial cell assessmentImportantNot an ICL-specific requirementAnterior chamber depthImportantNot an ICL requirementHigh myopiaMay be suitable for selected patientsDepends on corneal suitabilityImplant remains inside eyeYesNo

This comparison explains why a patient with thin corneas may be evaluated differently for ICL than for SMILE Pro.

Who May Be a Good ICL Candidate With Thin Corneas?

Possible Candidate Characteristics

A patient with thin corneas may still be considered for ICL when they have characteristics such as:

• Stable refractive error
• Appropriate myopia range for the lens
• Suitable anterior chamber depth
• Appropriate anterior chamber angle
• Adequate endothelial cell density
• Healthy overall ocular structures
• No significant contraindicating eye disease
• Appropriate expectations about the procedure
• Ability to attend postoperative follow-up

These are general considerations rather than a guarantee of candidacy.

Why the Full Examination Matters

Two patients can have the same corneal thickness and completely different ICL candidacy.

One may have a healthy anterior chamber and sufficient endothelial cells.

The other may have shallow anterior chamber anatomy or another eye condition that makes implantation inappropriate.

This is why ICL candidacy cannot be determined from a single number.

What Could Make ICL Unsuitable?

Internal Eye Anatomy

A shallow anterior chamber can create problems because the implant requires adequate space inside the eye.

The anterior chamber angle also needs to be appropriate.

These are among the reasons detailed measurements are essential before surgery.

Eye Pressure and Glaucoma

Glaucoma or significant ocular hypertension can affect ICL candidacy.

Current FDA labeling lists moderate to severe glaucoma as a contraindication and excludes ocular hypertension or glaucoma from the clinical study population.

If you have a history of elevated eye pressure, make sure your ophthalmologist knows before treatment planning.

Inflammation or Other Eye Disease

A history of uveitis or significant ocular inflammation may also affect suitability.

Other conditions, including cataract, certain retinal diseases, or previous eye surgery, may require additional assessment.

The decision should always be based on a complete medical history and eye examination.

What Tests Should You Expect at an ICL Consultation in Korea?

Vision and Prescription Testing

The clinic will usually confirm your current prescription and visual acuity.

If you wear contact lenses, you may need to stop wearing them before certain measurements because contact lenses can temporarily affect corneal shape.

The appropriate discontinuation period depends on the type of lens and the clinic's protocol.

Corneal and Anterior Segment Testing

Depending on the clinic, testing may include:

• Corneal topography
• Corneal tomography
• Pachymetry
• Anterior chamber depth measurement
• Anterior chamber angle assessment
• Endothelial cell analysis
• Eye pressure measurement

These tests provide a much more complete picture than corneal thickness alone.

Retinal Examination

Patients with significant myopia may need a detailed retinal examination.

The purpose is to identify existing retinal changes that could influence the safety or timing of refractive surgery.

This is particularly important for patients with high myopia, regardless of whether they are considering ICL or laser vision correction.

What Are the Benefits of ICL for Patients With Thin Corneas?

No Intentional Corneal Reshaping

The main potential advantage is straightforward: ICL does not require the central corneal tissue removal used in laser refractive surgery.

For an appropriately selected patient, this can make ICL a useful alternative when corneal tissue considerations make laser surgery less attractive.

Potential Option for Higher Prescriptions

ICL can also be useful for selected patients with higher prescriptions.

Research comparing ICL and SMILE in high myopia has found both procedures to be effective, with some studies reporting favorable refractive and visual-quality outcomes after ICL.

However, these findings should not be interpreted as proof that ICL is better for every patient.

What Are the Limitations of ICL?

ICL Is Intraocular Surgery

One major consideration is that ICL is an intraocular procedure.

Potential complications can include changes in eye pressure, inflammation, cataract formation, endothelial cell loss, lens-related problems, infection, or the need for repositioning, exchange, or removal.

The FDA also identifies specific anatomical and ocular health requirements for EVO ICL.

Visual Disturbances Can Occur

Some patients may experience glare, halos, or other visual symptoms after ICL.

Research comparing ICL and SMILE has found that halos can occur with both procedures, with some studies reporting them more frequently after ICL.

Your individual prescription, pupil size, eye anatomy, and healing response can influence postoperative visual quality.

ICL vs SMILE Pro for Patients With Thin Corneas

Which One May Be More Appropriate?

If corneal thickness is the main reason you are not considered a good candidate for laser vision correction, ICL may be worth discussing.

However, the choice should not be made from corneal thickness alone.

A patient with thin corneas and suitable internal eye anatomy may be considered for ICL.

A patient with thin corneas plus inadequate anterior chamber depth or insufficient endothelial cell density may not be.

This is why a comprehensive evaluation is essential.

What Research Says

Comparative studies have found that ICL and SMILE can both effectively correct high myopia. A meta-analysis of 12 studies involving 1,390 eyes found broadly comparable efficacy, while ICL showed advantages in some safety and higher-order aberration measures, particularly in shorter-term follow-up.

A four-year study also found both procedures effective and safe for selected high-myopia patients, while noting differences in long-term predictability and optical quality.

These studies support individualized decision-making rather than the idea that one procedure is universally superior.

How Much Does ICL Cost in Korea?

Factors That Affect the Price

ICL pricing can vary according to:

• Lens model
• Toric or non-toric lens
• Preoperative diagnostic testing
• Surgeon and facility fees
• Medication
• Postoperative examinations
• Whether one or both eyes are treated
• Services for international patients

Patients should ask for a current, itemized treatment quotation after their examination.

Cost should be considered alongside medical suitability, surgeon experience, diagnostic quality, and follow-up arrangements.

What Should International Patients Know About ICL in Korea?

Do Not Book Surgery Before Confirming Candidacy

If you are traveling from another country, it can be tempting to schedule surgery before arriving.

However, your eligibility may depend on detailed measurements that cannot be confirmed from an online consultation alone.

If possible, provide recent eye records before traveling and allow enough time in Korea for a proper examination and any necessary follow-up.

Plan for Postoperative Care

International patients should ask:

• How many follow-up visits are recommended?
• How long should I remain in Korea?
• When is it safe to fly?
• What symptoms require urgent attention?
• What should I do if a problem develops after returning home?
• Can the clinic coordinate with an ophthalmologist in my home country if needed?

A clear follow-up plan is especially important because ICL is an intraocular procedure.

Why Consider ICL in Korea?

Focus on Medical Evaluation Rather Than Marketing

South Korea has a highly developed healthcare system and advanced ophthalmic services, but patients should still evaluate individual clinics carefully.

When considering ICL in Korea, look for:

• Comprehensive diagnostic testing
• Qualified ophthalmic care
• Clear explanation of alternatives
• Transparent discussion of risks
• Appropriate lens selection
• Postoperative monitoring
• International patient communication
• Clear pricing and follow-up arrangements

The goal should be appropriate medical care rather than simply choosing a clinic because it advertises a particular technology.

How to Prepare for an ICL Consultation

Bring Your Previous Eye Information

If you have been told that your corneas are thin, bring any previous records showing:

• Central corneal thickness
• Corneal topography or tomography
• Glasses prescriptions
• Contact lens prescriptions
• Previous eye examinations
• Previous surgical records
• Retinal examination results

Previous measurements can help the ophthalmologist understand how your eyes have changed over time.

Ask Why You Were Rejected for Laser Surgery

If another clinic previously told you that you were not suitable for LASIK or SMILE Pro, ask for the specific reason.

Was it:

• Thin corneas?
• Irregular corneal shape?
• High myopia?
• Dry eye?
• Residual stromal bed concerns?
• Another ocular condition?

Knowing the exact reason can make your ICL consultation much more productive.

Conclusion

Yes, people with thin corneas can still potentially qualify for ICL surgery in Korea.

The key point is that thin corneas do not automatically disqualify you from ICL because ICL does not correct vision by removing corneal tissue.

However, ICL has its own requirements. Anterior chamber depth, anterior chamber angle, endothelial cell density, eye pressure, prescription stability, retinal health, and overall ocular health all need to be considered.

For someone who has been told that LASIK or SMILE Pro is unsuitable because of corneal thickness, an ICL evaluation may provide another option. But it should never be assumed that ICL is automatically appropriate.

The best next step is a comprehensive ophthalmic examination that evaluates both the cornea and the internal structures of the eye.

For international patients considering ICL in Korea, plan enough time for diagnostic testing, consultation, surgery, and postoperative monitoring. The right procedure is not determined by one measurement—it is determined by how well the entire treatment fits your eyes.

FAQs About Thin Corneas and ICL Surgery in Korea

1. Can I get ICL if I have thin corneas?

Possibly. Thin corneas do not automatically rule out ICL because ICL does not require the same type of corneal tissue removal as LASIK or SMILE Pro. Your internal eye anatomy and overall eye health still need to meet the necessary requirements.

2. Is ICL better than LASIK for thin corneas?

ICL may be considered when corneal thickness or other corneal characteristics make LASIK less suitable. However, ICL is intraocular surgery and has different risks, so it is not automatically better.

3. Can thin corneas qualify for SMILE Pro?

Some patients with relatively thin corneas may still qualify for SMILE Pro, depending on their corneal thickness, shape, prescription, and planned treatment. A detailed corneal evaluation is necessary.

4. What measurements are important for ICL candidacy?

Important measurements can include anterior chamber depth, anterior chamber angle, endothelial cell density, prescription stability, eye pressure, and overall ocular health.

5. What is the minimum corneal thickness for ICL?

There is no single minimum corneal thickness that determines ICL candidacy in the same way that corneal thickness is considered for laser tissue removal. ICL candidacy depends more heavily on internal eye anatomy and other health measurements.

6. Can ICL treat high myopia with thin corneas?

It can be considered for selected patients with high myopia and thin corneas. Current EVO ICL labeling includes specific high-myopia ranges, but candidacy also depends on anterior chamber depth, endothelial cell density, and other factors.

7. Can ICL be removed later?

An ICL can potentially be repositioned, exchanged, or removed when medically necessary. However, patients should not think of ICL as a procedure that can be casually reversed; it is intraocular surgery with its own risks.

8. Does ICL weaken the cornea?

ICL does not weaken the cornea through intentional corneal tissue removal in the way corneal laser surgery does. However, the procedure has other risks that should be discussed with an ophthalmologist.

9. Can ICL correct astigmatism too?

Yes. A toric ICL may be used for selected patients with myopic astigmatism when their prescription and eye anatomy meet the requirements of the specific lens.

10. How can I know if I qualify for ICL in Korea?

A comprehensive eye examination is the only reliable way to determine candidacy. If you have thin corneas, ask the ophthalmologist to evaluate your corneal measurements as well as anterior chamber depth, endothelial cell health, eye pressure, retina, and overall eye health.