Sometimes, yes. High myopia and thin corneas are the two findings that most often move a patient away from SMILE Pro and towards an implantable lens, but neither one settles the question by itself. What settles it is arithmetic done on your own eye: how much corneal tissue the correction would use, how much tissue you have, and what has to be left untouched afterwards. That is measured at the screening examination, one eye at a time, and the same examination shows whether an ICL is the better route if SMILE Pro is not.
Why the two findings are linked
SMILE Pro corrects vision by removing a thin disc of tissue, the lenticule, from inside the cornea. The thickness of that disc is not fixed. It grows with the amount of correction, so a higher prescription means a thicker lenticule and more tissue removed. Your corneal thickness, on the other hand, is whatever it is. The examination is really asking whether the second number can accommodate the first while leaving a safety margin underneath.
This is why the answer cannot be read off a prescription. A person with high myopia and a thick cornea may have more room than a person with moderate myopia and a thin one. The prescription tells you the size of the withdrawal. It says nothing about the balance in the account.
What the examination measures
Corneal thickness is mapped across the whole surface rather than taken at one central point, because the thinnest point is what matters and it is not always in the centre. Tomography records the curvature of both the front and the back surface of the cornea. The back surface is included because early irregularity often shows there first, and an irregular cornea is a reason to stop regardless of how thick it is. Where the equipment allows it, the thickness of the epithelium, the cornea's outer layer, is mapped separately, since an uneven epithelium can hide an irregular shape beneath it.
Alongside these, the examination confirms that your prescription has been stable, measures your pupil in dim light, and assesses the tear film. None of these is specific to high myopia, but all of them feed into the same decision.
There is also a first gate before any of this: the treatment range the laser platform is approved for. A correction outside that range is not stretched to fit. It goes to the alternative route from the start.
How the decision is actually made
The surgeon works out what would remain of the cornea after the lenticule is removed, and compares it with the margin the clinic requires. Three outcomes are possible.
The first is a clear fit: the correction sits within range, the remaining tissue is comfortably above the margin, and the shape is regular. The second is borderline: the arithmetic passes, but only just, or the shape is regular but not ideal. Here surgeons legitimately differ, and a cautious recommendation against SMILE Pro is not a mistake. The third is a clear no: the remaining tissue would fall below the margin, or the tomography shows a pattern that rules out corneal surgery entirely.
Thickness does not override shape. A thick cornea with an irregular map is still a no. Shape findings are the ones that end the conversation about laser procedures, whereas thickness findings usually redirect it.
When ICL becomes the recommendation, and what it requires
An implantable collamer lens is placed inside the eye and leaves the cornea alone, which is why it is the natural alternative when tissue is the limit. It is not, however, an automatic yes. The lens needs room, so the depth of the anterior chamber is measured. The cells lining the inside of the cornea are counted, because the lens will sit near them for life. The internal dimensions of the eye are measured to choose the lens size. A patient can be unsuitable for SMILE Pro on thickness and also unsuitable for an ICL on chamber depth. That is uncommon, but it is why both sets of measurements are taken in the same session.
What this means if you are travelling
Do not book flights on the assumption that SMILE Pro is the procedure you will have. Book them around the examination, which covers both routes and is the point at which the answer becomes known. Bring your prescription history, because stability is part of the decision. Observe the contact lens break the clinic gives you, since a cornea still reshaped by lenses cannot be measured accurately, and the thickness and tomography readings are exactly what this decision depends on.
GS Eye Center (GS안과) is an eye clinic at Gangnam Station Exit 1, Seoul, open since 2005. Patients with high myopia or borderline corneal thickness are assessed for both SMILE Pro and ICL at the same examination, and the recommendation follows the measurements rather than the procedure the patient arrived expecting.