American patients increasingly arrive at a consultation asking for a specific procedure by name rather than for "LASIK" as a catch-all. That is a healthy shift, but it carries a trap: choosing a procedure from marketing copy before anyone has measured your corneas. This guide lays out how the three approaches differ as neutral medical information, then explains which measurements actually make the decision.
How does each procedure work?
SMILE: lenticule extraction through a small incision
SMILE (small incision lenticule extraction) uses a femtosecond laser to cut a thin, lens-shaped piece of tissue - a lenticule - inside the intact cornea, then removes it through an incision of about 2 mm. Removing the lenticule flattens the cornea and corrects nearsightedness and astigmatism. There is no flap: the corneal surface stays largely intact, which is why the technique is often discussed for active lifestyles and contact sports. GS Eye Center performs SMILE on the ZEISS VISUMAX 500 and SMILE Pro on the newer VISUMAX 800. SILK is a separate procedure, performed at the clinic on the Johnson & Johnson ELITA platform.
LASIK: reshaping under a flap
LASIK creates a hinged flap in the outer cornea, lifts it, reshapes the tissue underneath with an excimer laser, and lays the flap back down. Visual recovery is typically fast, and LASIK has a long modern track record, including the ability to treat farsightedness. The tradeoffs are flap-related: the flap can be displaced by significant trauma, and because more corneal nerves are cut than in SMILE, dry eye is a well-documented effect; it usually improves, but in some people it lasts longer or is more severe and needs further treatment. At GS, LASIK is performed without a blade: the ZEISS VISUMAX femtosecond laser creates the flap and an excimer laser reshapes the cornea.
ICL: an implanted lens, no tissue removed
ICL (implantable collamer lens) takes a different path entirely: a soft corrective lens is placed inside the eye through a small incision, behind the iris and in front of the natural lens. ICL is one type of phakic intraocular lens, meaning a lens implanted while the eye's own lens stays in place. No corneal tissue is removed, which is why ICL is often considered for very high prescriptions or corneas too thin for laser surgery. The lens can later be removed or exchanged by a surgeon, but that is additional intraocular surgery with its own risks. GS stocks four phakic lens types - EVO+ ICL (STAAR, USA), KPL (Koryoeyetech, Korea), GLAZE (Biotech), and Artiflex (OPHTEC, Netherlands) - so the lens is matched to the eye rather than the other way around. Artiflex is an iris-fixated lens, a different type of phakic lens, not an ICL.
What does the comparison look like side by side?
| Factor | SMILE / SMILE Pro | LASIK | ICL |
|---|---|---|---|
| Approach | Lenticule removed through ~2 mm incision, no flap | Corneal flap lifted, tissue reshaped by excimer laser | Corrective lens implanted behind the iris, in front of the natural lens; no tissue removed |
| Corneal tissue | Removed (lenticule) | Removed (ablation under flap) | Preserved |
| Typical early recovery | Many daily activities resume early, per clinic materials; your surgeon sets the timing | Fast visual recovery; flap needs protection early on | Staged: surgery plus scheduled follow-up checks |
| Corrects | Nearsightedness, astigmatism (the scope offered at this clinic) | Nearsightedness, astigmatism, farsightedness | High nearsightedness and astigmatism (lens-dependent) |
| Often considered for | Active lifestyles, dry-eye concern, contact sports | Broad standard cases, farsighted patients | Very high prescriptions, thin corneas, laser-ineligible eyes |
| Reversibility | Not reversible (tissue removed) | Not reversible (tissue removed) | Lens can be removed or exchanged by a surgeon; this is additional surgery |
| Key considerations | Dry eye, night glare and regression can occur; astigmatism alignment and surgeon experience with the platform | Flap trauma risk; dry eye, which usually improves but can last longer in some people | Intraocular surgery; risks include raised eye pressure, endothelial cell loss and cataract; sizing and rotation for toric lenses |
Compare these options alongside your examination results. Each row becomes decisive only in combination with your measurements. Correctable ranges also differ by country and device approval; at this clinic they are confirmed against Korean approvals and your examination.
Who tends to be a candidate for each?
Corneal thickness is the classic gatekeeper. Laser procedures work by removing tissue, so the cornea must have enough to spare - the higher your prescription, the more tissue correction requires. Patients with thin corneas or very strong prescriptions often find that laser surgery would leave too little margin, which is exactly the situation phakic lenses were designed for. GS's clinical materials list the common reasons laser surgery is declined: insufficient corneal thickness, corneal disease or scarring, severe dry eye, suspected keratoconus, low endothelial cell counts, and certain systemic conditions.
Lifestyle plays a supporting role. The flapless structure of SMILE is frequently preferred by people who box, wrestle, or serve in the military. LASIK's longer history and farsightedness coverage keep it the default for many standard cases. ICL's preservation of the cornea appeals to patients who value the option of removal later, although removal is itself surgery. But lifestyle preference only applies within the set of procedures your eyes actually qualify for.
What risks should you weigh?
All three procedures are widely studied in the published literature, and all three carry real risks that deserve plain language. Laser procedures: dry eye is common in the early months, night glare and halos can occur, and a degree of regression (partial return of the prescription) is possible over time. Enhancement procedures exist for suitable cases. GS's published FAQ describes most post-laser effects - dryness, glare, light sensitivity - as mild and typically improving within about six months, with individual variation; in some people, dry eye or glare lasts longer or is more severe and needs further treatment. ICL: because the lens sits inside the eye, the U.S. FDA's patient information on phakic lenses lists risks that include raised pressure inside the eye, loss of corneal endothelial cells (the cell layer that keeps the cornea clear), and cataract; infection or other serious complications can permanently affect vision. Toric (astigmatism-correcting) lenses can rotate and may need repositioning, and removing or exchanging a lens is itself additional surgery. This is why surgeons monitor eye pressure and the corneal endothelium over the long term, and GS's ICL program includes scheduled aftercare checks for the implant.
Any clinic, in any country, that tells you a refractive procedure has no risks is not giving you medical information. The realistic goal is a procedure whose specific risk profile your eyes are well positioned to tolerate.
Why does the exam decide, not the brochure?
Because every deciding variable is a measurement. Corneal thickness and topography rule laser procedures in or out. Scotopic pupil size informs how the optical zone is planned, which relates to night vision quality. Anterior chamber depth and endothelial cell counts determine ICL eligibility - GS's protocol for lens implantation runs five dedicated preliminary checks covering vision, lens positioning, endothelial cells, the optic nerve, and the retina. Prescription stability over time separates good candidates from patients who should wait. None of this is visible from the outside, and none of it can be guessed from a forum thread.
At GS Eye Center the preoperative screening runs to around 50 diagnostic tests, and the surgeon reviews the results with you before any procedure is scheduled. If you are comparing procedures from the U.S., the practical first step is to send us your prescription and any recent exam data. Your coordinator passes your records to the medical team; after the medical team reviews them, you are told which options are worth evaluating further, before you book a flight. The final decision follows the in-person examination.
Related pages: SMILE Pro · ICL implantation · LASIK & LASEK