Patients often arrive already guessing which procedure they'll get based on a number from an old glasses prescription. The real answer comes from a few specific measurements — here's what they are and roughly how they're read.
I'm Dr. Baek Dong-won, Representative Director at EYEONCE Eye Clinic in Gangnam, Seoul. A lot of the anxiety patients bring to this decision comes from trying to self-diagnose off one number — usually the sphere power on an old glasses prescription. That number matters, but it's one input among several. Below are the general reference ranges we work from, written as general guidance, not a diagnosis for your specific eyes.
A prescription around -5.00 is generally considered moderate myopia, and it sits comfortably within the range that LASIK and LASEK or SMILE-based correction have treated reliably for a long time — assuming your cornea comes back from the exam as a normal, healthy thickness with no irregular shape. For most patients at this level, the real decision isn't "can this be corrected," it's which of the laser-based paths fits your lifestyle and corneal profile best.
Astigmatism gets corrected alongside myopia in the same laser procedure in the large majority of cases — it's not automatically a complication. Where it starts to matter more is when a meaningful degree of astigmatism shows up together with higher myopia, because correcting both at once asks more of the available corneal tissue than correcting either one on its own. That combination is exactly where the next section's tipping point tends to show up sooner.
Every laser procedure works by removing a precise amount of corneal tissue — more removal for a higher prescription. There's a point, different for every patient, where the prescription is high enough (or the cornea thin enough to begin with) that the tissue removal needed would leave the cornea less stable long-term than we're willing to accept. That's the point where ICL becomes the better-suited option instead — not a downgrade, a different tool that corrects the same myopia and astigmatism from inside the eye without removing corneal tissue at all. We wrote more about this specific trade-off in our earlier guide on high myopia and astigmatism.
Two patients can walk in with the exact same glasses prescription and leave with different recommendations, and that's not inconsistency — it's because the prescription number only tells part of the story. Corneal thickness, corneal shape, pupil size and overall eye health all vary independently of your prescription, and those are the measurements that actually decide which procedure is safe for you specifically.
Corneal topography, pachymetry (thickness mapping) and a current refraction are the measurements that turn a general reference range into an actual answer for your eyes. Nothing above replaces that exam — it's meant to explain the reasoning behind it, so the recommendation you get makes sense rather than feeling arbitrary.
If SMILE PRO is on your list, SMILE PRO in Korea: the exam-day words, explained translates the terms you will hear.
The ranges above are general reference points, not a diagnosis. Which procedure is actually safe for your eyes can only be confirmed through corneal topography, pachymetry and a current refraction at an in-person exam.
Representative Director, EYEONCE Eye Clinic Gangnam · Former Clinical Instructor, Dept. of Ophthalmology, Samsung Seoul Hospital · Member, Korean & American Societies of Cataract and Refractive Surgery · Last reviewed October 2026
International patients share what actually happened — from their first fears to waking up the next morning without glasses.
Our patients share their stories on Google — verified, public and unfiltered. Open the map to read every review straight from the source.
Tell us your prescription and travel dates. Our English-speaking team will design your personalized plan — free of charge, no pressure.
An English-speaking eye clinic in the heart of Gangnam, Seoul — moments from Sinnonhyeon Station and easily reached from Incheon International Airport.
5–6F, Duo Sinnonhyeon, 368 Sapyeong-daero, Seocho-gu, Seoul, South Korea
+82-10-6308-0984 — English, Chinese, Mongolian & Thai
Mon, Tue, Thu, Fri 09:00–18:00 · Sat 09:00–16:00 · Lunch break 13:00–14:00 · Closed Wed & Sun
By appointment only · Registration may close early depending on the day’s schedule.
Sinnonhyeon Station (Line 9 / Sinbundang Line) — 3 min walk. Gangnam Station (Line 2) nearby.