CLEAR and SMILE: What Actually Differs Between Them

What is the difference between CLEAR and SMILE? Both are lenticule extraction procedures: a femtosecond laser shapes a thin disc of corneal tissue, called a lenticule, inside the cornea, and the surgeon removes it through a small incision without lifting a flap. The difference is the laser platform they run on, and the software, energy settings and surgical steps that come with it. CLEAR is performed on the Ziemer system, SMILE and SMILE Pro on the ZEISS system.

That is the short answer. The longer answer is that the differences a patient can feel are narrower than the amount written about them, and the factors that will actually decide your outcome sit somewhere else entirely.

The family they both belong to

It helps to place them on a map. Corneal laser vision correction splits into three approaches:

CLEAR and SMILE sit in the same row. That is why the comparison is a narrow one: they share the mechanism. If you are comparing across rows instead, our piece on the difference between SMILE Pro and SMILE LASIK covers that adjacent question.

Where the two actually differ

The honest list is short, and most of it is engineering rather than experience.

• The laser platform. Different manufacturers, different pulse characteristics and energy profiles, different software controlling the cut.
• Surgical steps. The sequence for separating and removing the lenticule is not identical between platforms, and surgeons trained on one develop a feel for it.
• Planning software. Each platform has its own nomogram and its own treatment planning tools.
• Incision geometry. Both use a small incision rather than a flap; the exact size and position are set by the platform and the plan.

What is not on that list is as important as what is. We are not going to tell you that one recovers faster, one is safer, or one is newer and therefore better. Published comparisons have generally found early recovery to be broadly similar, and the spread between individual patients is wider than the gap between the two names.

What decides your result instead

The examination decides almost everything before the platform question arises:

1. Corneal thickness and shape. How much tissue is available, and whether the shape map shows anything that would rule out a corneal procedure.
2. Prescription and stability. Both the amount of myopia and astigmatism, and whether it has stopped changing.
3. Tear film. Dry eye before surgery is the single most common reason people are less comfortable after it.
4. Pupil size. Relevant to night vision expectations.

For some eyes the answer from all of that is that neither procedure is appropriate, and a lens-based option is the better route. Our piece on who is not a candidate goes through those situations directly.

How to use this at a consultation

A useful set of questions, none of which require you to know anything about lasers:

1. Which procedures can you offer, and which can you not? A clinic committing to one platform is normal. A clinic that will not say what it lacks is a different matter.
2. What did my examination rule out, and why? The reasoning matters more than the conclusion.
3. What is the plan if the result is undercorrected? Retreatment options after a lenticule procedure are not identical to those after a flap procedure, and this is worth asking before rather than after.
4. What does my tear film look like, and what are we doing about it? This one changes your experience more than the platform name does.

The platform is the last question on that list, not the first. A patient who has understood their own examination is in a better position than one who has memorised two brand names.

Gangnam Smile Eye Clinic (강남스마일안과) is a vision-correction and cataract clinic on Gangnam-daero, Seoul. This article was reviewed by our medical staff for clinical accuracy. It is general information about surgical techniques and not a diagnosis, a comparison of providers, or a treatment recommendation for any individual.

FAQ

Are CLEAR and SMILE the same procedure?

They belong to the same family. Both are lenticule extraction procedures: a femtosecond laser shapes a thin disc of tissue, called a lenticule, inside the cornea, and the surgeon removes it through a small incision without creating a flap. They are not the same product. CLEAR runs on the Ziemer platform and SMILE on the ZEISS platform, and each has its own software, energy settings and surgical steps.

Does one have a faster recovery than the other?

We do not make that claim. Both are flap-free lenticule procedures, and published comparisons have generally found the early recovery pattern to be broadly similar, with differences between individual patients larger than differences between the two names. What changes your recovery more reliably is your prescription, your tear film, and whether you follow the drop schedule.

Which one is right for me?

That is decided by the examination, not by the platform name. Corneal thickness, the shape map, pupil size, tear film and the stability of your prescription all narrow the options before the choice of machine becomes relevant. For some eyes neither is appropriate and a lens-based option is the better route.

Is the incision size different?

Both use a small incision measured in millimetres rather than the larger hinged flap of LASIK. The exact figure varies with the platform, the software version and the surgical plan, so it is a number to ask about in your own consultation rather than to take from an article.

If a clinic only offers one of them, is that a problem?

Not by itself. These are expensive platforms and most clinics commit to one. What matters is whether the clinic is honest about which procedures it can and cannot offer, and whether it will tell you plainly when your eyes would be better served by something it does not have.