Implantable Collamer Lens (ICL): What the Evidence Says for BC Patients

The Implantable Collamer Lens — widely known by its brand name Visian ICL — generates a great deal of interest from patients who have been told they are not suitable for LASIK or PRK. As with any elective procedure that involves placing a device inside the eye, the decision warrants careful, evidence-informed consideration. This article aims to do exactly that: present what the peer-reviewed literature shows about the ICL — its benefits, its risks, and the genuine limitations of the current evidence base — in plain language.

I want to be direct at the outset: the ICL is not a cataract surgery lens. It is not relevant to patients who have cataracts. I will clarify that distinction below, because confusion between phakic IOLs and cataract IOLs is common and matters for the decisions you make about your eye care.

What Is the Implantable Collamer Lens?

The ICL is a phakic intraocular lens — meaning it is implanted inside the eye while leaving your natural crystalline lens in place. It is made from Collamer, a soft biocompatible material containing collagen co-polymer developed by STAAR Surgical. The lens is folded and inserted through a small incision, then positioned in the posterior chamber between the iris and the natural lens. Once unfolded, it rests in place without requiring sutures.

The purpose of the ICL is to correct refractive error — specifically, to reduce or eliminate dependence on glasses or contact lenses in patients with myopia (nearsightedness), hyperopia (farsightedness), or astigmatism. Current-generation ICL models (the EVO+ ICL and its predecessor the V4c) incorporate a central aqueous channel (KS-AquaPORT) that allows fluid to circulate without requiring a pre-operative laser peripheral iridotomy — a key improvement over earlier designs.

Who Is the ICL Indicated For?

The ICL is typically considered for patients who:

• Have moderate to high myopia — particularly above –6.00 dioptres, where LASIK outcomes are less predictable or where insufficient corneal tissue limits laser treatment.
• Are not suitable candidates for LASIK or PRK — due to thin corneas, irregular corneal topography, significant dry eye, or a prescription outside the range of corneal laser treatment.
• Have stable refraction — typically defined as less than 0.5 dioptre of change per year for at least 1–2 years before surgery.
• Have adequate anterior chamber depth — the space between the cornea and lens must be sufficient to accommodate the ICL safely. This is measured by anterior segment imaging (e.g., Scheimpflug or OCT).
• Do not have significant cataract, glaucoma, uveitis, or other contraindications to intraocular surgery.

The ICL is approved for myopia up to approximately –18.00 dioptres and hyperopia up to approximately +10.00 dioptres in various jurisdictions, though clinical candidacy is determined by thorough individual assessment rather than dioptric range alone.

What the Evidence Shows

Efficacy Data

The ICL has a reasonably well-established short- to medium-term efficacy record. A large prospective multicentre study by Sanders and Vukich (Journal of Refractive Surgery, 2006) reported that 59% of myopic patients achieved uncorrected visual acuity of 20/20 or better at one year, and 95% were within 0.50 dioptre of their intended target refraction — outcomes that compare favourably with LASIK in comparable prescriptions. Subsequent studies of the EVO+ generation have reported similar or improved outcomes.

A 2019 systematic review by Fernandes et al. in the Journal of Cataract and Refractive Surgery (JCRS) examined phakic IOL outcomes across multiple peer-reviewed studies and concluded that the ICL produced predictable and stable refractive outcomes for moderate to high myopia, with good long-term stability of refraction when appropriate candidates are selected. Rotational stability — an important consideration for the toric (astigmatism-correcting) version — has also been demonstrated in multiple published series.

An important nuance: the majority of the ICL's published evidence base originates from manufacturer-sponsored trials and registry data. Independent investigator-initiated studies and Cochrane-level systematic reviews are less numerous than for LASIK or cataract IOLs with decades of accumulated independent literature. This does not invalidate the existing evidence — but a balanced reader should weight this context appropriately.

ICL vs. LASIK: What the Comparative Evidence Shows

Several randomised and prospective comparative studies have examined ICL versus LASIK in high myopia. A notable randomised trial by Ganesh et al. published in Clinical Ophthalmology (2014) found that ICL produced significantly better uncorrected visual acuity and contrast sensitivity compared to LASIK for myopia above –8.00 dioptres, with greater stability of refraction at 3 years. The JCRS has published multiple comparative series with broadly consistent findings favouring ICL over LASIK for high myopia in terms of refractive predictability and contrast sensitivity.

For low to moderate myopia (below approximately –6.00 dioptres), where LASIK outcomes are generally excellent, the comparative advantage of the ICL is less clear, and the additional surgical risk and cost of an intraocular procedure must be carefully weighed. LASIK and PRK have an enormous long-term safety record in this range. The ICL is not the default first choice for all myopic patients — it is a considered alternative for specific clinical scenarios.

Risks and Limitations

This is a section I want patients to read carefully. The ICL is an intraocular procedure, and intraocular procedures carry risks that corneal laser procedures do not. The relevant documented risks in the peer-reviewed literature include:

Elevated Intraocular Pressure

Transient or sustained elevation of intraocular pressure (IOP) can occur after ICL implantation, related to inflammation, impaired aqueous flow, or vault-related factors. Earlier ICL designs (without the central aqueous channel) carried a higher risk of pupillary block — a sight-threatening form of acute angle-closure glaucoma. The current EVO+ design has substantially reduced this risk, but IOP monitoring in the immediate post-operative period remains important and should be managed by an ophthalmologist experienced with this procedure.

Anterior Subcapsular Cataract Formation

This is arguably the most clinically significant long-term risk of the ICL. Contact between the posterior surface of the ICL and the anterior lens capsule — typically related to insufficient vault (the gap between the ICL and the natural lens) — can cause anterior subcapsular opacification over time. Long-term studies, including the 10-year data published by Fernández-Vega et al. in Ophthalmology (2009), report cataract formation in a subset of patients, with cumulative incidence increasing with follow-up duration and vault insufficiency. Accurate sizing of the ICL — dependent on precise pre-operative white-to-white and anterior chamber depth measurements — is the primary mitigation strategy. Vault that is too high carries different risks (corneal endothelial contact, elevated IOP). Getting the sizing right is genuinely important and requires experienced surgical assessment.

Pupillary Block and Glaucoma Risk

Pupillary block glaucoma — caused by obstruction of aqueous flow between the posterior and anterior chamber — was a recognised complication of earlier ICL models without a central perforation. The KS-AquaPORT in current EVO and EVO+ designs was specifically engineered to address this by allowing continuous aqueous flow without a surgical iridotomy. Published data suggest this has substantially reduced the incidence of pupillary block with current-generation lenses, though patients with narrow angles or other anatomical risk factors require careful pre-operative evaluation.

Corneal Endothelial Cell Loss

The corneal endothelium — the innermost layer of cells that keep the cornea transparent — does not regenerate. Any intraocular procedure carries some risk of endothelial cell loss. Published ICL studies report relatively modest endothelial cell density reduction over time in appropriately vaulted lenses, but this should be monitored with specular microscopy, particularly in patients with borderline pre-operative endothelial cell counts. A vault that is too high increases contact risk with the corneal endothelium.

Other Surgical Risks

As with any intraocular surgery, there is a small risk of infection (endophthalmitis), retinal detachment, and other procedural complications. The absolute risk of serious complications in experienced hands is low but not zero, and is meaningfully higher than for a corneal surface procedure such as LASIK — because accessing the interior of the eye inherently carries greater consequences if something goes wrong.

Limitations of the Current Evidence Base

It is worth being explicit about the structure of the ICL evidence base, because it differs meaningfully from that of procedures like LASIK or cataract surgery:

• Industry-sponsored trials dominate. The pivotal FDA trial data and a substantial proportion of the published series are sponsored by or conducted in close collaboration with the device manufacturer. This does not make the findings wrong, but independent replication is the gold standard in evidence-based medicine, and independent long-term data are less available.
• No independent Cochrane systematic review has been completed specifically for phakic IOLs with adequate power and follow-up as of the time of this writing. The evidence level for the ICL, while encouraging, does not match the depth available for LASIK or standard cataract IOLs.
• Selection bias in published series. Published outcomes naturally tend to come from experienced high-volume centres with carefully selected patients. Real-world outcomes in less experienced settings may vary.
• Comparator issues. Many comparative studies compare ICL to older LASIK protocols or platforms. The relevant comparison today would be against modern wavefront-guided or topography-guided LASIK or SMILE, and such contemporaneous trials are limited.

Cost Considerations in BC

ICL surgery is not covered by BC's Medical Services Plan (MSP). It is an elective, entirely out-of-pocket procedure. The total cost includes the lens itself (which is a significant component), surgical facility fees, anaesthesia or sedation where used, and pre- and post-operative assessments. Fees vary by provider and should be obtained in writing, itemised, before any commitment.

Patients should be aware that the total commitment is not only financial. Post-operative monitoring is important — IOP checks, vault assessment, and endothelial cell counts should be performed at defined intervals. The relationship with your surgeon does not end on surgery day, and access to ongoing follow-up care is part of the overall picture.

Questions to Ask Your Surgeon

If you are considering the ICL, the following questions are worth raising at your consultation:

1. Am I a confirmed non-candidate for LASIK or PRK? And on what specific basis — corneal thickness, topography, prescription range, dry eye? Understanding why you are being directed toward ICL rather than corneal laser surgery matters.
2. What vault do you anticipate for my anatomy, and how will you confirm sizing pre-operatively? Proper sizing is central to the risk profile of the procedure. Ask what imaging is used (white-to-white, anterior OCT, or sulcus-to-sulcus measurement) and how sizing decisions are made.
3. What is your personal complication rate for elevated IOP, cataract formation, and lens explantation? Outcomes vary by surgical experience. Ask specifically about the surgeon's own series, not industry averages.
4. What happens if I develop a cataract in 10 or 15 years? The ICL would need to be explanted at the time of cataract surgery. Understanding this scenario — and the implications for biometric calculations and IOL selection — is relevant for younger patients in particular.
5. What are the total costs, and what is included in post-operative follow-up? Are IOP checks, vault measurements, and specular microscopy included? For how long?