SMILE PRO in Korea, explained through the words you'll hear on exam day

Wondering whether SMILE PRO Korea is a realistic option for your eyes, or just another tab you've left open?

Read on before you book flights or pay a deposit, because a few exam-day terms decide most of the answer.

After this you will know what a lenticule is, which measurements (pachymetry, topography) decide whether SMILE PRO is possible, what the risks and aftercare look like, and how many days to plan in Seoul.

I'm Dr. Baek Dong-won, Representative Director of Eyeonce. SMILE PRO is flapless and works through a 2–4 mm keyhole incision, which is why I explain it carefully: people often assume "no flap" means "suitable for everyone," and it doesn't.

Short answer: SMILE PRO is a laser correction for nearsightedness and astigmatism that removes a thin disc of tissue from inside the cornea, and whether it suits you depends on your measurements.

A lenticule is a thin, lens-shaped piece of corneal tissue that the laser outlines inside the cornea. Taking it out flattens the front surface, which corrects nearsightedness. A 2014 review in Eye and Vision by Reinstein, Archer and Gobbe describes the opening used to remove it as typically 2–3 mm, with sizes varying between techniques.

You'll see two older approaches on the same menu, and the difference is mostly about what happens to the top layers of the cornea:

• LASIK lifts a hinged flap from the front of the cornea, reshapes the tissue underneath with an excimer laser, then lays the flap back.
• LASEK removes only the thin surface skin (the epithelium), treats the surface directly and lets that skin grow back over several days.
• SMILE leaves the front layers largely in place and works through the small opening, which is why it's called flapless.

The same review points out that the front part of the corneal stroma is its strongest region, and SMILE disturbs it less than a flap does. That's a mechanical argument about tissue, not a promise about your result, and it is weighed against your own measurements.

Eyeonce lists SMILE PRO and SMILE LASIK as separate items. If a plan names one of them, it's fair to ask me which one it is and why it fits your numbers. There's a separate piece on how SMILE LASIK compares with flap LASIK if you want that comparison in more depth.

The cap is the layer of cornea left above the lenticule; the residual bed is the untouched tissue beneath it. A higher prescription needs a thicker lenticule, so more tissue comes out, and the real question becomes whether enough remains for the cornea to stay stable for decades.

This is where people with strong prescriptions, or who were told their corneas are “on the thin side”, tend to get stuck. When I look at an eye at -3.00 D with a cornea a little thinner than average, there may be plenty of room. At -8.00 D with an average cornea, there may not be, because the lenticule for that correction is much thicker. I'm less interested in the thickness number by itself than in what it leaves behind once that lenticule is out.

When the arithmetic is tight, two alternatives are worth discussing. LASEK works on the surface and avoids a flap or cap. An implantable lens such as the EVO Aqua ICL corrects vision without removing corneal tissue at all, which is why it comes up for high myopia. If your prescription combines strong nearsightedness with astigmatism, the piece on how high myopia and astigmatism are assessed together goes further.

When someone asks me whether they “qualify” for SMILE PRO, I understand the wish for a yes or a no before booking a flight. What answers that is the map, the thickness and how stable your prescription is, read together. If those three point away from removing tissue, I would rather say so on exam day and talk through LASEK or an ICL than fit the eye to the procedure someone came for.

Say you are strongly nearsighted and an optician once told you your corneas looked thin. You would not need to guess from that remark. I would start with the corneal thickness and topography maps, then work out how much tissue the lenticule for your prescription would take. I would also look at how much cornea would remain afterwards and whether the shape of the surface raises any concern. If the numbers leave enough margin, SMILE PRO can be discussed. If they don't, I would say so and talk through other options. The prescription alone never settles it, which is why the measurements come first.

SMILE is surgery, and it carries risks: dry eye, glare and halos at night, under- or over-correction that may need further treatment, and uncommon surgical complications. Most early symptoms ease over weeks to months, but not every one disappears, and some eyes are better left untreated.

Dry eye. The 2014 review summarizes studies in which corneal sensation dropped less and recovered faster after SMILE than after LASIK, which is the basis for expecting less dryness on average. Dryness can still occur. I co-authored Textbook of Dry Eye (2019), and this is the part of your history I want in detail: how many hours a day you wear contacts, whether they start to sting by mid-afternoon, and whether you already use drops. For a contact-lens wearer, those answers can weigh as much as the corneal map.

Glare and halos. The U.S. Food and Drug Administration's patient page on laser vision correction notes that glare, halos and difficulty driving at night may persist while vision stabilizes, and that stabilization can take up to three to six months.

Regression and enhancement. Sometimes the eye drifts back toward nearsightedness, or the first correction lands a little off. The FDA advises waiting until measurements are consistent for two visits at least three months apart before any further surgery. After SMILE, the retreatment route differs from LASIK; the 2014 review describes surface treatment as one option, with others depending on how the first procedure was done.

Is the result lasting? The tissue that is removed does not grow back, so for many eyes the correction holds for years. It is not fixed for life, though: some eyes regress, and no laser correction stops presbyopia, the age-related loss of near focus that usually brings reading glasses in middle age.

Uncommon complications. The same review lists suction loss during the laser step, small tears at the edge of the opening, a lenticule that is hard to separate, and a fragment of lenticule left behind. These are reported as uncommon, and most have established ways of being managed, but you should hear about them before you sign a consent form.

Who is usually asked to wait, or steered elsewhere

• a prescription that is still changing
• a corneal map suggestive of keratoconus or other irregularity
• a cornea that is thin relative to the correction needed
• significant dry eye or eye-surface disease that hasn't been treated yet
• pregnancy or breastfeeding, when prescription and tear film can shift

The in-person exam decides suitability. A good outcome for one eye says nothing certain about the next.

The decision to fly is made at that first check, based on how the cornea surface looks and how your vision is settling, not on a fixed rule. Later checks can often happen with an eye doctor at home, which is why the records mentioned above matter.

The clinic calendar shapes the plan too. Eyeonce is at 5–6F, Duo Sinnonhyeon, 368 Sapyeong-daero, Seocho-gu, Seoul. Hours are Mon, Tue, Thu, Fri 09:00–18:00 and Sat 09:00–16:00, with a lunch break 13:00–14:00. The clinic is closed Wednesdays and Sundays, an appointment is required, and registration may close early depending on demand.

A flight landing on Tuesday evening does not lead to a Wednesday exam; Thursday is the next clinic day. Because dilation blurs near vision for hours, don't book an afternoon flight on the exam day.

From Incheon Airport the options are a taxi, AREX plus the subway, or a limousine bus, and Eyeonce's main site has the directions. If you're still weighing flap LASIK and LASEK as well, see what to check before booking laser vision correction in Korea.

Send one photo of your latest prescription, or any topography or thickness printout you already have, on WhatsApp, together with the dates you're considering for Seoul.