Implantable Collamer Lens (ICL) surgery can be an option for people who want to reduce their dependence on glasses or contact lenses, particularly those with moderate to high myopia. However, having a strong prescription alone does not make you eligible.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
Before ICL surgery, your eyes need to meet specific requirements related to your age, prescription stability, eye anatomy, corneal health, and overall eye condition. A detailed examination helps determine whether ICL surgery is appropriate for you.
What Does ICL Eligibility Mean?
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
ICL eligibility refers to whether your eyes and general circumstances meet the requirements for safely implanting a phakic intraocular lens.
Unlike a procedure that removes the natural lens of the eye, an ICL is placed inside the eye while the natural lens remains in place. Because the implant occupies space inside the eye, the surgeon needs to evaluate the anatomy and health of your eye carefully before recommending treatment.
Eligibility can also vary depending on the specific ICL model, its approved indications, and the country where treatment is being performed.
Who May Be Eligible for ICL Surgery?
Although individual requirements vary, a potential ICL candidate generally needs to meet several criteria.
1. You Are an Adult Within the Appropriate Age Range
ICL surgery is generally intended for adults. The appropriate age range depends on the specific lens and its regulatory approval.
For example, the FDA-approved indications for the EVO/EVO+ ICL have historically specified patients aged 21 to 45 years for correction of myopia. Other ICL models or indications may have different age ranges.
This is why age should be considered together with the specific lens being proposed rather than treated as a universal eligibility cutoff.
2. Your Prescription Is Within the Lens's Approved Range
ICL is particularly useful for people with moderate to high myopia, including prescriptions that may be outside the practical treatment range of some corneal laser procedures.
The exact refractive range depends on the lens model. For the FDA-approved EVO/EVO+ ICL indication, the correction range includes myopia from -3.0 diopters through -15.0 diopters, with reduction of myopia above -15.0 D up to -20.0 D, subject to additional requirements.
If you also have astigmatism, a toric version of the ICL may be considered when the prescription falls within the approved range for that lens.
3. Your Prescription Has Been Stable
A stable prescription is an important part of ICL eligibility. If your myopia is still changing significantly, the refractive result from surgery may not be as predictable.
Current FDA labeling for the EVO/EVO+ ICL specifies a stable refractive history within 0.5 diopters for one year before implantation. Your ophthalmologist may review previous prescriptions and perform repeated measurements to establish stability.
4. Your Eye Has Enough Internal Space for the Lens
The ICL is positioned behind the iris and in front of the eye's natural crystalline lens. There must therefore be adequate space for the implant to sit safely.
One important measurement is the anterior chamber depth (ACD). For the FDA-approved EVO/EVO+ ICL indication, an ACD of at least 3.00 mm, measured from the corneal endothelium to the front surface of the natural lens, is required.
A shallow anterior chamber may make ICL implantation unsuitable because the available space inside the eye is an important consideration for safe positioning of the lens.
5. Your Corneal Endothelial Cells Are Adequate
The inner surface of the cornea contains endothelial cells that help maintain corneal clarity. These cells are important when evaluating candidates for an implantable lens.
An endothelial cell count is therefore measured before ICL surgery. The minimum acceptable density depends on factors such as age and the anatomy of the eye. If the endothelial cell count is below the required level, ICL surgery may not be recommended.
6. Your Anterior Chamber Angle Is Suitable
The angle between the iris and cornea is another part of the preoperative assessment. Gonioscopy may be used to examine this area and determine whether the angle is sufficiently open. An angle that is too narrow can increase the risk associated with placing an intraocular lens.
7. Your Eyes Are Generally Healthy
ICL surgery is elective refractive surgery, so the overall health of the eye matters. Your ophthalmologist may examine the cornea, iris, natural lens, retina, optic nerve, and eye pressure before deciding whether surgery is appropriate.
Conditions that may affect eligibility or require additional evaluation can include:
- Glaucoma or elevated eye pressure
- Active inflammation inside the eye, such as uveitis
- Cataract
- Significant retinal or macular disease
- Certain corneal conditions
- Previous eye surgery
- Other progressive or sight-threatening eye conditions
The presence of a condition does not necessarily have the same implications for every patient. The ophthalmologist has to assess its severity, stability, and potential effect on the safety and outcome of ICL surgery.
Does Having Thin Corneas Make You Eligible for ICL?
Thin corneas do not automatically make someone eligible for ICL, but they can be an important factor when comparing refractive surgery options.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
Because ICL is placed inside the eye rather than reshaping the cornea, it may be considered in some people who are not suitable candidates for corneal laser procedures because of corneal thickness or other corneal characteristics.
However, the eye still needs to meet the anatomical and health requirements for an intraocular lens. Thin corneas alone are therefore not enough to determine whether ICL is appropriate.
What Tests Are Done Before ICL Surgery?
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
A comprehensive ICL assessment typically involves more than checking your glasses prescription. Depending on your circumstances, your evaluation may include:
- Detailed refraction: Measures your current prescription.
- Prescription history: Helps establish whether your refractive error is stable.
- Anterior chamber measurements: Determine whether there is sufficient space for the ICL.
- Corneal evaluation: Assesses the shape and health of the cornea.
- Endothelial cell count: Measures the density and health of corneal endothelial cells.
- Eye pressure measurement: Helps identify glaucoma or elevated intraocular pressure.
- Gonioscopy: Examines the angle between the iris and cornea.
- Retinal examination: Checks the back of the eye for abnormalities, particularly important in people with high myopia.
- Biometry and other eye measurements: Help determine the appropriate lens specifications.
Can You Be Eligible for ICL If LASIK Is Not Suitable?
Sometimes. ICL and corneal laser procedures work differently, so a person who is not suitable for LASIK may still be evaluated for an ICL.
For example, some people may have very high myopia, corneal characteristics, or other factors that make a corneal laser procedure less suitable. ICL may then be considered if the internal anatomy and overall health of the eyes meet the requirements.
However, being unsuitable for LASIK does not automatically mean that you qualify for ICL. The two procedures have different eligibility criteria.
What Happens If You Do Not Meet the ICL Criteria?
Not meeting one ICL requirement does not necessarily mean that no vision-correction option is available.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
Depending on the reason, your ophthalmologist may recommend waiting until the prescription becomes stable, treating an underlying eye condition first, considering another refractive procedure, or deciding that refractive surgery is not appropriate.
The purpose of the eligibility assessment is not simply to determine whether an ICL can technically be inserted. It is to establish whether the procedure is reasonably appropriate for your individual eyes.
The Bottom Line
Being eligible for ICL surgery involves much more than having a high glasses prescription. A suitable candidate generally needs an appropriate age and prescription, stable refractive error, adequate space inside the eye, sufficient corneal endothelial cell health, and no significant condition that would make implantation unsafe or unsuitable.
A detailed eye examination is therefore essential before deciding whether ICL is appropriate. The final recommendation should be based on the complete picture of your eye health and measurements, rather than on prescription strength alone.
