ICL (Implantable Collamer Lens)

Introduction

If you are considering ICL surgery, you have likely already explored vision correction options — perhaps glasses and contact lenses for many years, and possibly LASIK or other laser procedures that turned out not to be suitable for your eyes. ICL, which stands for Implantable Collamer Lens, is an alternative approach to permanent vision correction. Instead of reshaping the cornea, as laser surgery does, a small flexible lens is placed inside the eye to focus light correctly onto the retina.

ICL is often considered by people with higher prescriptions, thinner corneas, dry eyes, or other features that make laser surgery less appropriate. It is also chosen by patients who prefer a procedure that does not permanently change the shape of the cornea.

This article explains what ICL surgery is, who is generally considered a good candidate, how it compares with other options like LASIK and SMILE, what the procedure and recovery look like, and what to think about for the long term. It is written for adults who are planning treatment, not for emergency reading or first-time symptom checking.

What Is ICL?

ICL stands for Implantable Collamer Lens. It is a soft, flexible lens that is surgically implanted inside the eye to correct refractive errors — the focusing problems that cause blurry vision. The lens is positioned behind the iris (the coloured part of the eye) and in front of the natural lens. Because it is added to the eye rather than replacing any tissue, an ICL is classified as a phakic intraocular lens, meaning the eye's own natural lens stays in place.

The material the lens is made from is called collamer, a biocompatible blend of collagen and a polymer. Collamer is designed to sit inside the eye without triggering rejection or irritation. The lens is also designed to be invisible from the outside — once implanted, neither the patient nor anyone looking at them can see that it is there.

ICL is primarily used to correct myopia (nearsightedness, where distant objects appear blurry) and can also correct astigmatism (a focusing irregularity caused by an uneven cornea) when a special toric version of the lens is used. The most widely used ICL today is the EVO version, which has a small central port that allows fluid to circulate naturally inside the eye, removing the need for a separate procedure to create a drainage channel in the iris.

Unlike laser vision correction, ICL is reversible in principle — the lens can be surgically removed if needed, although removal is uncommon.

Why Is ICL Surgery Performed?

The goal of ICL surgery is to reduce or eliminate dependence on glasses and contact lenses by correcting the eye's focusing error. Doctors may consider ICL for several reasons:

• High myopia. ICL can correct very high prescriptions — typically up to around -18 dioptres — that fall outside the safe range for most laser procedures.
• Thin or irregular corneas. LASIK and similar procedures remove corneal tissue. If the cornea is already thin, or has an irregular shape such as in early keratoconus or forme fruste keratoconus, laser surgery may not be safe. ICL leaves the cornea untouched.
• Severe dry eye. Laser procedures can worsen dry eye, at least temporarily. For patients with significant baseline dry eye, ICL is often preferred because it does not affect the corneal nerves in the same way.
• Patient preference for a reversible option. Some patients prefer that the cornea remain unchanged, in case future technologies or treatments become available.
• Astigmatism alongside myopia. The toric ICL combines correction for both in a single lens.

ICL does not treat presbyopia — the age-related loss of near focus that develops in most people in their 40s. Patients who have ICL surgery will still typically need reading glasses as they age, in the same way that someone with naturally good distance vision will.

Who Is a Candidate?

Candidacy for ICL surgery is decided through a detailed eye examination and a discussion with a refractive surgeon. The criteria that doctors generally look for include:

• Age. ICL is typically considered for adults from around age 21 to 45. The lower limit is because the eye continues to grow and the prescription can change through the late teens. The upper limit is flexible, but as patients enter their late 40s and 50s, the natural lens begins to develop changes that may make lens-based surgery (such as refractive lens exchange) a more logical choice.
• Stable prescription. The glasses or contact lens prescription should have been stable for at least a year, ideally longer. A still-changing prescription suggests the eye has not yet settled.
• Healthy eyes overall. The eye must be free of active infection, significant cataract, uncontrolled glaucoma, or other conditions that could affect surgical safety or results.
• Sufficient space inside the eye. ICL requires enough room between the iris and the natural lens to safely accommodate the implant. This space is measured during the pre-operative work-up using high-resolution imaging.
• Healthy corneal endothelium. The endothelium is the inner cell layer of the cornea. These cells do not regenerate, and any intraocular surgery causes some endothelial cell loss. Doctors check the endothelial cell count to confirm a healthy baseline.
• Prescription within the corrective range. ICL is approved for myopia from around -3 up to -18 dioptres, and astigmatism up to around 6 dioptres. Lower prescriptions are sometimes treated with ICL too, but laser options are also commonly used in that range.

Pregnancy and breastfeeding are typically reasons to delay surgery, because hormonal changes can shift the prescription temporarily. Patients with certain autoimmune conditions, a history of recurrent eye inflammation, or specific structural abnormalities may not be candidates.

Alternatives to ICL

LASIK

LASIK (Laser-Assisted In Situ Keratomileusis) is the best known refractive surgery. A thin flap is created in the cornea, an excimer laser reshapes the underlying tissue, and the flap is laid back. Recovery is fast and visual results are typically excellent for low to moderate prescriptions. LASIK is not suitable when the cornea is too thin, when the prescription is very high, or when there are signs of corneal weakness.

SMILE

SMILE (Small Incision Lenticule Extraction) is a flap-free laser procedure in which a small disc of tissue (a lenticule) is created within the cornea using a femtosecond laser and removed through a small incision. SMILE may be preferred for patients with dry eyes or active lifestyles. Like LASIK, it is limited by corneal thickness and the size of the prescription.

PRK and LASEK

PRK (Photorefractive Keratectomy) and the related LASEK reshape the cornea without creating a flap. The surface epithelium is removed and regrows over several days. These options are sometimes chosen for patients with thinner corneas or those whose occupations carry a risk of eye impact. Recovery is slower and more uncomfortable than with LASIK or SMILE.

Refractive Lens Exchange

Refractive lens exchange (RLE) is essentially cataract surgery performed before a cataract has developed. The natural lens is replaced with an artificial intraocular lens chosen to correct the prescription. RLE is more commonly considered in patients over about 45, particularly those who also want to address presbyopia with a multifocal or extended-depth-of-focus lens.

Glasses and Contact Lenses

Non-surgical correction remains an entirely reasonable choice. Modern lenses are lightweight and comfortable, and daily disposable contact lenses are widely available. Surgery is elective; the decision to pursue it is personal.

How ICL compares with these options is something a refractive surgeon evaluates based on the individual eye. For high prescriptions, thin corneas, and significant dry eye, ICL is frequently the recommended approach. For lower prescriptions with healthy, thick corneas, laser procedures are often the more common choice.

Types of ICL

The current generation of ICL most widely used is the EVO Visian ICL, manufactured by STAAR Surgical. Within this family, there are two main variants:

EVO ICL (Spherical)

This version corrects myopia alone. It is the most commonly implanted ICL.

EVO Toric ICL

This version corrects both myopia and astigmatism. It must be oriented at a specific angle inside the eye, calculated from the pre-operative measurements, so that the astigmatic correction aligns correctly with the eye's own astigmatism.

Both versions feature the central port (a small opening in the centre of the lens) that allows fluid in the eye to circulate naturally. Earlier generations of ICL required a separate small hole to be made in the iris before or during surgery; the central port has made this step unnecessary in most cases.

Hyperopic (farsightedness) ICLs exist but are less commonly used and are not available in all regions. The discussion in this article focuses on the more widely performed myopic and toric versions.

Preparing for ICL Surgery

• Refraction. Measurement of the current prescription, often after using drops to relax the eye's focusing muscles.
• Corneal topography and tomography. Detailed mapping of the corneal surface and thickness to rule out keratoconus or other irregularities.
• Anterior segment imaging. Measurement of the space inside the front of the eye to choose the correct lens size. This may use ultrasound biomicroscopy or anterior segment optical coherence tomography (AS-OCT).
• Endothelial cell count. Specular microscopy to check the health of the inner corneal cell layer.
• Intraocular pressure measurement. To check for glaucoma risk.
• Dilated retinal examination. To check the back of the eye, especially important in high myopia where the retina can be thinner and more vulnerable to tears.

If contact lenses are normally worn, the surgeon will ask that they be left out for a period before the measurements — commonly around one to two weeks for soft lenses and longer for rigid lenses — because contact lenses can temporarily change the shape of the cornea and affect the readings.

The lens itself is custom-ordered to the size and power calculated from the work-up. This usually means there is a wait of one to several weeks between the final measurements and the date of surgery, while the lens is manufactured and shipped.

In the days before surgery, the surgeon may prescribe antibiotic and anti-inflammatory eye drops to begin shortly before the procedure. Patients are typically asked to avoid eye makeup, perfumes, and lotions around the eye on the day of surgery, and to arrange transport home as they will not be able to drive immediately after.

What Happens During ICL Surgery

ICL surgery is an outpatient procedure, usually performed under topical anaesthesia — numbing eye drops rather than a general anaesthetic. A mild sedative may be offered to help with relaxation. Most patients are in the operating area for about 30 to 45 minutes, with the actual surgery on each eye taking roughly 10 to 15 minutes.

The main steps are:

1. Preparation. The skin around the eye is cleaned, and a small device gently holds the eyelids open. Numbing drops are applied.
2. Incision. The surgeon makes a small incision at the edge of the cornea, typically around 3 millimetres long. This incision is self-sealing and does not usually require stitches.
3. Lens insertion. The folded ICL is loaded into a small injector and inserted through the incision. Inside the eye, the lens gently unfolds.
4. Positioning. The surgeon manoeuvres the lens behind the iris and in front of the natural lens. For a toric ICL, the lens is rotated to its calculated alignment.
5. Final checks. The surgeon confirms the lens is correctly positioned and that intraocular pressure is normal.

The second eye is usually treated either on the same day or a few days later, depending on the surgeon's preference and local practice.

Most patients describe seeing bright lights and a feeling of pressure during the surgery rather than pain. The eye is numb, and although the procedure is happening on the eye itself, the experience is more akin to a strange visual sensation than a painful one.

Recovery and Healing

• The first 24 hours. The eye may feel slightly gritty or sensitive to light. Mild watering and the sensation of something in the eye are common. A protective shield is often worn while sleeping for the first few nights to prevent accidental rubbing.
• The first week. Most patients return to non-strenuous work within a few days. Eye drops — antibiotic and anti-inflammatory — are used several times a day on a tapering schedule. Vision continues to stabilise.
• Weeks two to four. Vision typically reaches close to its final quality. Most normal activities, including driving (once the surgeon confirms vision is adequate), can be resumed.
• One to three months. Final visual outcome is generally stable. Follow-up visits are scheduled to confirm lens position, intraocular pressure, and visual acuity.

Certain activities are restricted during recovery. Surgeons commonly advise:

• Avoiding rubbing the eyes for several weeks
• Avoiding swimming, hot tubs, and submerging the head in water for two to four weeks
• Avoiding contact sports and activities with a risk of impact to the eye for at least a month, and longer for high-impact sports
• Using protective eyewear in dusty or windy environments during early recovery
• Avoiding eye makeup for one to two weeks

Follow-up visits are scheduled in a typical pattern: the day after surgery, around one week, one month, three months, and then at six and twelve months, with annual reviews thereafter.

Risks and Complications

ICL surgery has a strong safety record when performed by an experienced refractive surgeon on appropriately selected patients, but like any intraocular surgery it carries risks. These should be discussed in detail at the consultation.

Short-term risks

• Infection. Endophthalmitis — an infection inside the eye — is rare but serious. Antibiotic drops are used to minimise this risk.
• Inflammation. Some inflammation inside the eye is expected and is treated with anti-inflammatory drops. Significant inflammation is uncommon.
• Raised intraocular pressure. Pressure inside the eye can rise in the early days after surgery. This is monitored closely and treated with drops if needed.
• Lens decentration or rotation. The lens can occasionally shift from its ideal position, particularly with toric lenses where alignment matters. A small additional procedure may be needed to reposition the lens.

Longer-term considerations

• Cataract formation. Earlier generations of ICL were associated with a measurable risk of cataract over time, related to the lens making contact with the natural lens. The current EVO generation, with its central port and refined design, has substantially reduced this risk, although it has not been eliminated. If cataract does develop — whether age-related or surgery-related — the ICL can be removed at the time of cataract surgery.
• Endothelial cell loss. Some loss of corneal endothelial cells occurs after any intraocular surgery. The rate of long-term loss with modern ICL is generally low, but lifelong monitoring is recommended.
• Glare and halos. Some patients notice halos around lights, particularly at night, especially in the first months. These usually become less noticeable over time. Patients with larger pupils may be more prone to this.
• Under- or over-correction. The final prescription may not be exactly zero. Small residual refractive errors can sometimes be managed with glasses or, if appropriate, with an additional laser touch-up.
• Need for lens exchange. Rarely, the lens may need to be replaced with a different size or removed entirely.

Retinal complications such as retinal detachment are a concern in patients with high myopia regardless of whether surgery is performed, because the retina in highly myopic eyes is thinner and more vulnerable. ICL surgery does not cause myopia-related retinal disease, but it does not protect against it either, and lifelong retinal monitoring is important for anyone with a high prescription.

Life After ICL Surgery

For most people who undergo ICL surgery, the result is a significant reduction or elimination of dependence on glasses and contact lenses for daily activities. Many patients report being able to see clearly on waking, drive comfortably at night, and participate in sports and outdoor activities without correction for the first time in many years.

That said, some longer-term realities are important to plan for:

• Presbyopia will still happen. Around the mid-40s, most people begin to need help with near vision. ICL corrects distance vision; it does not prevent the age-related stiffening of the natural lens. Reading glasses are likely to be needed eventually, just as they would be for anyone.
• Cataract surgery, when needed, is still possible. If a cataract develops later in life, the ICL is removed and a standard intraocular lens is implanted, much the same as any cataract operation.
• Annual eye examinations remain important. Patients who had high myopia continue to be at higher risk of retinal problems and should have dilated retinal examinations regularly. Monitoring of intraocular pressure and endothelial cell count is also part of long-term follow-up.
• The lens is designed to last. ICLs are intended to remain in the eye indefinitely. They do not need replacement on a routine schedule.

For patients whose vision improvement is meaningful but not complete, glasses for specific situations (such as night driving) may still be useful. Some patients choose to have a laser touch-up procedure if a small residual prescription remains, although this is a separate decision made after the ICL has fully settled.

Frequently Asked Questions

Will I be able to feel the lens inside my eye?

No. The ICL sits behind the iris and is not in contact with the cornea or other sensitive structures in a way that produces sensation. Patients do not feel the lens, and it is not visible from the outside.

Is ICL reversible?

In principle, yes. The lens can be surgically removed if necessary, and the eye returns to its pre-surgical state in terms of the natural anatomy. In practice, lens removal is uncommon and is usually done only if a complication develops or at the time of later cataract surgery.

How does ICL compare with LASIK for results?

Both procedures produce excellent visual results in appropriately selected patients. The choice between them is largely about which procedure is most appropriate for the individual eye. For low to moderate prescriptions with healthy, thick corneas, LASIK is often the more common choice. For higher prescriptions, thinner corneas, or significant dry eye, ICL is frequently preferred. Quality of vision after either procedure, when well chosen, is generally comparable.

Can ICL correct astigmatism?

Yes. The toric ICL is specifically designed to correct astigmatism along with myopia. The lens is oriented at a specific angle calculated from the pre-operative measurements.

Can I have ICL in both eyes on the same day?

Practice varies. Some surgeons operate on both eyes on the same day, particularly when the patient prefers a single recovery period. Others prefer to operate on one eye first and the second eye a few days later, to allow the first eye to be checked before proceeding. Both approaches are accepted; the choice is discussed during the consultation.

How long does the lens last?

The ICL is designed to be a permanent implant. It is not replaced on a schedule. Most patients can expect the lens to remain in place for life, unless cataract surgery or another intervention requires its removal.

Will I still need glasses after ICL?

The goal is to reduce or eliminate the need for distance glasses. Most patients achieve this. However, glasses may still be useful in specific situations — for example, fine night driving correction if a small residual prescription remains, or reading glasses once presbyopia develops in the 40s and beyond.

Is the surgery painful?

The eye is numbed with drops, so the surgery itself is not painful. Most patients describe pressure and bright light during the procedure rather than pain. Some mild discomfort — grittiness, watering, or light sensitivity — is common in the first day or two and is managed with the prescribed drops.

What if my prescription changes again later?

The ICL corrects the prescription as it was at the time of surgery. If a small change develops over time, options include glasses, contact lenses, or, in some cases, an additional laser touch-up. Major prescription changes after surgery are uncommon in adults whose prescription was stable beforehand.

How soon can I go back to work?

Many patients with desk-based work return within two to three days. Jobs involving dust, chemicals, heavy physical activity, or risk of eye impact may require longer time off. The surgeon will give specific guidance based on the kind of work involved.

Can I exercise after ICL surgery?

Light exercise such as walking is usually fine within a few days. More vigorous exercise, swimming, and contact sports are restricted for several weeks. The specific timeline depends on the activity and the surgeon's advice.

Conclusion

ICL surgery is an established and well-studied form of permanent vision correction, particularly valuable for patients whose prescription, corneal shape, or other features make laser procedures less appropriate. The lens sits invisibly inside the eye, can correct high prescriptions and astigmatism, and leaves the cornea untouched. Recovery is usually rapid, and most patients achieve a significant improvement in their independence from glasses and contact lenses.

Like any intraocular surgery, ICL carries risks that should be carefully weighed, and long-term follow-up remains important — both for the lens itself and for the underlying eye health, particularly in patients with high myopia. The decision about whether ICL is the right approach, and how it compares with alternatives such as LASIK, SMILE, PRK, or refractive lens exchange, is one to make in detailed conversation with a refractive surgeon who has examined the individual eye and reviewed the full set of measurements.