ICL and implantable lenses: when a laser is not the right tool for a high prescription
When a very high prescription rules out laser, a small lens placed inside the eye is the other route. Here is who it suits, what the checks look for, the honest risks, and why a highly short-sighted parent's child needs an early eye check.
- Laser removes corneal tissue, and a higher prescription needs more removed. The Royal College of Ophthalmologists says laser is most likely to suit prescriptions up to -10.00D, and thin corneas, keratoconus or severe dry eye can rule it out.
- An ICL (Implantable Collamer Lens, one brand of phakic implantable lens) sits behind the iris in front of the natural lens, removes no corneal tissue, and can in principle be taken out by a second operation.
- The FDA booklet for the EVO ICL says candidates are aged 21 to 45, with a prescription from -3.0 D to -20.0 D, a stable number for at least 1 year, and an anterior chamber depth of 3.0 millimeters or more.
- The main risks are cataract, raised eye pressure, loss of corneal cells and halos. In a Barcelona series followed for a mean of 11.35 years, 3 of 45 eyes (7%) developed a cataract.
- The eye stays long, so retinal checks for high myopia continue for life, and the lens does not stop presbyopia. High myopia is partly inherited, so the child of a highly short-sighted parent needs an early eye check.
A parent with a very high prescription may have been told years ago that laser surgery was not suitable for them, and may wonder whether anything else exists. There is a different kind of operation for that situation. It is worth understanding, partly because a very high prescription runs in families, and the child of such a parent is on the same road.
Why can't everyone with a high prescription have laser surgery?
Because laser surgery works by removing a little of the cornea, the clear front window of the eye, and a high prescription needs more removed. The American Academy of Ophthalmology (AAO) puts it this way: "With LASIK surgery, the more nearsighted you are, the more tissue we need to remove from the cornea. If a person is very nearsighted (or has a thin cornea), he or she may not have enough tissue to remove."
The Royal College of Ophthalmologists, which sets standards for eye surgeons in the United Kingdom, gives the range where laser is most likely to suit: "Up to -10.00D of myopia or short sight". Its leaflet adds that laser "can be effective for higher prescriptions in some patients", so this is a guide, not a wall. Thin corneas, keratoconus and severe dry eye are separate reasons, as the LASIK age rule article sets out.
The action: have a refractive surgeon measure the cornea before assuming a laser is out of reach. The guide to LASIK, SMILE and PRK sets out what each laser does.
What is an ICL, and how is it different from laser surgery?
It is a small lens placed inside the eye, with no tissue removed. The ICL (Implantable Collamer Lens, a brand made by STAAR Surgical, and the name most people search) belongs to a group called phakic implantable lenses. "Phakic" means the eye keeps its own natural lens. The AAO describes them as "clear implantable lenses that are surgically placed either between the cornea and the iris (the colored portion of the eye) or just behind the iris, without removing a person's natural lens".
The ICL sits behind the iris and in front of the natural lens. The Royal College of Ophthalmologists says these lenses are "implanted in front of the natural lens without replacing it", and that in younger patients they are "often a good alternative where the spectacle prescription is outside the normal range for laser vision correction".
Because the cornea is left alone, the lens can in principle be taken out or exchanged with a second operation. The FDA's patient booklet for one version of the ICL lists "another surgery to take out, replace or adjust the position" of the lens among the risks. That is reversible in principle, not a promise that removal is trivial.
It is an operation inside the eye, and the AAO notes that it "still comes with higher risk than laser surgery".
Who is an implantable lens suitable for, and at what age?
An adult with a stable high prescription and a suitable eye. The FDA patient booklet for the EVO ICL says a candidate must "be between the ages of 21 and 45" and "have between -3.0 D and -20.0 D of nearsightedness and no more than 4.0D of astigmatism". It also asks for "written evidence that your nearsightedness has been stable for at least 1 year". The same booklet says you should not have the surgery if you are "less than 21 years of age".
That is why a teenager is not a candidate, however thick the glasses. The number is usually still moving and the age limit has not been reached. Surgery in children is a separate and rare matter, covered in refractive surgery in children.
The action: an adult who is curious should see a refractive surgeon, and a teenager should stay in current glasses and keep every prescription record.
What do the checks before an implantable lens look for?
They look at whether the lens will fit safely inside this particular eye. The FDA booklet lists several tests and limits.
- Anterior chamber depth. The front compartment of the eye must be deep enough: "an anterior chamber depth of 3.0 millimeters or greater". The booklet says the lens should not be used if the chamber is narrower than 3.0 millimeters.
- Endothelial cell count. The endothelium is a single layer of cells on the inner surface of the cornea that keeps it clear. A candidate needs a "minimally acceptable density" of these cells for their age.
- Eye pressure and the drainage angle. The booklet says safety has not been established in people with glaucoma or ocular hypertension, so pressure is measured before and checked after.
- Lens sizing. The booklet says the shape of the eye must be "able to fit" the lens, so the eye is measured carefully to choose the right size.
The action: bring every glasses record to the assessment, and ask which measurement decided the advice.
What are the risks, and what do the long-term studies show?
The main ones are cataract, raised eye pressure, loss of corneal cells and halos. The FDA booklet states that "the risk of a cataract continues to rise with each year that the EVO ICL lens is in the eye" and that "the long-term risk of cataract beyond 7 years is unknown". It says patients "experience some loss of endothelial cells and a continuing loss of endothelial cells over time that is greater than that expected from aging", and that "even if patients don't have glare and halos before EVO ICL surgery, they may develop glare and halos after surgery". It also warns of an early rise in eye pressure after surgery.
For the numbers, one long-term series followed 45 eyes of 26 patients for a mean of 11.35 years after ICL implantation in Barcelona (Journal of Cataract and Refractive Surgery, 2022). The average prescription before surgery was -10.06 D. At the last visit, 3 eyes (7%) had developed a cataract, and 2 eyes (4%) had lost two or more lines of best-corrected vision. Endothelial cell loss averaged 9.85%, with a wide spread (± 11.35%), and the eyes drifted by a further -0.75 D of short-sightedness on average. The authors judged the lens "effective, predictable, stable, and safe". It was a small, retrospective, single-centre series, so it cannot say how any one eye will behave.
A 2025 systematic review and meta-analysis of the newer lens models with a central port covered 27 studies and 2,204 eyes. Follow-up averaged only 13.84 months, so it speaks to the early picture. It reported no vision-threatening events and a decrease in endothelial cells it called "clinically acceptable".
The action: anyone with an ICL keeps the regular checks of eye pressure, corneal cells and the natural lens for as long as the lens is in, as the FDA booklet advises.
What does an implantable lens not change, and what are the other lens options?
It does not shorten a long eye. The lens corrects how light focuses, but the eyeball is as long as before, so the retinal risks that come with a long eye stay. The American Academy of Ophthalmology's 2021 clinical statement puts the risk of retinal detachment above -3.00 D at "10 times increased risk compared with non-myopic eyes", which is why a person with a high number keeps having retinal checks for life. High myopia: what changes once the number gets high explains what those checks look for.
It also does not stop presbyopia, the reading-vision change that the AAO says is "a normal part of aging" and that may start "shortly after age 40". An ICL wearer in their forties meets reading glasses like anyone else. PRESBYOND and laser blended vision covers what a laser can and cannot do about that.
One other lens operation is worth knowing by name, as education only. Refractive lens exchange replaces the natural lens with an implant. The Royal College of Ophthalmologists says it is "identical to modern cataract surgery" and "often preferred" for patients "in the retirement age group". It is not an operation for the young, because it removes the eye's own focusing lens.
Who does this in Malaysia, and what does it mean for my child?
It is performed by ophthalmologists, the eye specialists registered on the National Specialist Register kept by the Malaysian Medical Council. I am a paediatric ophthalmologist and I do not perform refractive surgery, so the person to assess an adult for it is a refractive surgeon. Ask the surgeon for the risks above in writing.
The family point is the one I would like a highly short-sighted parent to take away. High myopia is partly inherited. In the Sydney Myopia Study, short-sightedness in 12-year-olds rose with the number of short-sighted parents, from 7.6% with none to 14.9% with one and 43.6% with two. A child whose parent wears a very strong prescription is the child who most needs an early eye check and a proper look at myopia control. Your first child wears glasses: what about the second and slowing myopia down are the pages to start with.
Whatever is decided for the parent's eyes, the child's eye check can happen this year.
- Pain, redness or sharply reduced vision after any eye operation: contact the operating surgeon the same day.
- A child's glasses number jumps from one visit to the next, or the picture looks warped even with glasses on.
- Flashes of light, a shower of new floaters or a curtain over part of the view appear, which needs same-day assessment in anyone with high myopia.
- Halos, glare or a hazy cornea that are new or worsening in someone who already has an implanted lens.
- A child with a short-sighted parent is squinting at the board, sitting very close to screens, or has not had an eye check yet.
Common questions
What is an ICL for the eyes?
Who is suitable for ICL surgery?
Is ICL safer than LASIK?
Can an ICL be removed?
What are the risks of an implantable lens?
Does an ICL stop my eye power from changing or cure high myopia?
Does an ICL help with reading glasses after 40?
Will my child inherit my high myopia?
- US Food and Drug Administration · EVO ICL and EVO TICL (Visian Implantable Collamer Lens) patient information booklet · www.accessdata.fda.gov
- American Academy of Ophthalmology · Phakic intraocular lenses for nearsightedness · www.aao.org
- American Academy of Ophthalmology · Task Force on Myopia clinical statement 2021, reducing the global burden of myopia · www.aao.org
- American Academy of Ophthalmology · What is presbyopia? · www.aao.org
- Royal College of Ophthalmologists · Laser Vision Correction, patient information (copy of the leaflet) · bluefinvision.com
- Royal College of Ophthalmologists · Professional standards for refractive surgery · www.rcophth.ac.uk
- Journal of Cataract and Refractive Surgery 2022 · Papa-Vettorazzi et al, Long-term efficacy and safety after posterior chamber phakic IOL implantation, more than 10 years of follow-up · pubmed.ncbi.nlm.nih.gov
- Journal of Refractive Surgery 2025 · Larivoir et al, Phakic Implantable Collamer Lenses V4c and V5: systematic review and meta-analysis · pubmed.ncbi.nlm.nih.gov
- Investigative Ophthalmology and Visual Science 2007 · Sydney Myopia Study, ethnic differences in the impact of parental myopia · pubmed.ncbi.nlm.nih.gov
- National Specialist Register of Malaysia · About NSR · www.nsr.org.my