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Implantable Collamer Lens (ICL)

A removable lens implanted behind the iris to correct moderate to high myopia and astigmatism when corneal laser surgery is not ideal.

5 min read

The Implantable Collamer Lens (ICL) is a soft posterior-chamber phakic IOL placed in the ciliary sulcus - the narrow space between the back of the iris and the front of the natural crystalline lens. It corrects myopia and astigmatism without reshaping the cornea. It can be a strong option when prescription, corneal thickness, or corneal topography makes LASIK or PRK unsuitable.

Key Takeaways

  • ICL is a phakic IOL - placed inside the eye while the natural lens remains
  • FDA-approved for myopia from -3 to -20 D with 1.0 to 4.0 D of cylinder on the toric model - useful when corneal-based surgery is unsafe or out of range
  • The lens is removable or exchangeable, though the surgery itself is not risk-free or fully "erasable"
  • No corneal flap and no surface ablation - may produce less dry eye than LASIK in selected patients
  • Modern EVO ICL designs include a central port, so peripheral iridotomy is usually not needed

How the Procedure Works

  • Pre-operative measurements include white-to-white corneal diameter and anterior chamber depth, which determine the right ICL size
  • Small incision at the corneal edge under topical anesthesia
  • The folded ICL is inserted through the incision and positioned in the ciliary sulcus, behind the iris and in front of the natural crystalline lens
  • The natural lens is left in place
  • Older ICL models (without a central port) needed a small laser peripheral iridotomy to allow aqueous humor to circulate around the implant; if the iridotomy closed or was inadequate, pupillary block glaucoma could develop. The modern EVO ICL family has a central 360-micron port (KS-AquaPort) that maintains aqueous flow and obviates the need for an iridotomy in most cases

The procedure is typically 15-20 minutes per eye.

Who Is a Candidate

  • Myopia in the FDA-approved range (myopia from -3 to -20 D; 1.0 to 4.0 D of cylinder for the toric model)
  • Thin or borderline corneas where corneal-based surgery is risky
  • Suspect topography that excludes corneal procedures
  • Patient preference for a removable lens-based refractive procedure
  • Anterior chamber depth of at least 3.00 mm measured from the corneal endothelium (per FDA labeling for EVO ICL)
  • Healthy endothelium with adequate cell count
  • Stable refractive error
  • In the U.S., FDA PMA supplement P030016/S048 expanded the indicated EVO ICL age range from 21-45 to 21-60 for myopia and myopic astigmatism, with a decision date of November 14, 2025; international approvals and off-label use outside that range vary by surgeon and jurisdiction
  • Not pregnant or nursing

Recovery

  • Mild discomfort for 1-2 days
  • Topical antibiotic and steroid drops for 1-4 weeks
  • Vision often improves the same day; near-final at 1 week
  • Activity restrictions similar to cataract surgery (avoid heavy lifting, swimming, eye rubbing for 1-2 weeks)
  • Follow-up at 1 day, 1 week, 1 month, then yearly

Risks

  • Cataract - historically a concern with the original ICL; significantly reduced with newer designs and the central port. Lifetime risk varies by individual factors.
  • Pressure spikes - typically related to absent or inadequate iridotomy in older designs, or to vault problems
  • Pigment dispersion from contact with iris pigment
  • Endothelial cell loss over time
  • Vault problems - the gap between ICL and natural lens - too low or too high may require ICL replacement
  • Glare and halos - usually transient

Frequently Asked Questions

Will my own lens be removed?

No. The ICL is placed in front of your natural lens. Both lenses coexist. This contrasts with refractive lens exchange, in which the natural lens is removed and replaced with an artificial one.

Will I still develop cataracts?

Cataract development is age-related and will eventually occur in most people. ICL does not prevent cataract. When cataract surgery is needed, the ICL is removed and the natural lens is replaced with an IOL in the standard way.

Is this reversible?

It is better described as removable than fully reversible. The lens can be removed or exchanged if needed, and unlike LASIK, no corneal tissue is removed. But it is still intraocular surgery. Taking the lens out does not rewind every surgical risk or guarantee the eye is exactly as it was before.

How does it compare to LASIK and SMILE?

ICL is often considered for high myopia and for patients with thin or suspicious corneas. LASIK and SMILE are often considered before ICL for moderate myopia in healthy corneas. ICL costs more, requires intraocular surgery, and carries cataract and pressure risks; LASIK and SMILE have corneal tissue considerations.

References

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