Published clinic article
SMILE pro and SMILE correct vision by removing a thin piece of tissue from within the cornea through a small incision. LASIK creates a corneal flap before using a laser to correct vision. At SNU Eye Clinic, we use VISUMAX 800 for SMILE pro and also have VISUMAX 500, the earlier SMILE system. Understanding these differences is a useful starting point. Your choice should also take into account your corneal examination results, nearsightedness and astigmatism, and everyday activities.
How do SMILE, SMILE pro and LASIK differ?
The main differences are whether a corneal flap is created and how tissue is removed from the cornea. Although SMILE is called “SMILE LASIK” in Korean, the procedure differs from conventional LASIK.
| Comparison | SMILE | SMILE pro | LASIK |
|---|---|---|---|
| How vision is corrected | A lenticule formed within the cornea is removed through a small incision | The same principle as SMILE, performed with VISUMAX 800 | A corneal flap is lifted and the cornea is reshaped |
| Corneal flap | No | No | Yes |
| Equipment at SNU Eye Clinic | VISUMAX 500 available | VISUMAX 800 used | Confirm the proposed LASIK method during your examination and consultation |
| What to compare | Your eye condition, the range of correction and recovery | Your eye condition, plus the system’s centration and astigmatism-axis alignment assistance | The corneal flap, the range of correction and recovery |
A lenticule is a thin piece of tissue formed within the cornea for vision correction. ZEISS’s comparison of vision correction procedures also explains how SMILE procedures differ from LASIK. All three change how the eye focuses light, so suitability should be assessed using examination results, not the procedure’s name alone. Your consultation should also cover possible dryness, glare or halos, and differences between your expected and actual vision after surgery.
What is tailored in SMILE pro at SNU Eye Clinic?
Our “BESPOKE SMILE” approach means planning surgery for each eye, with adjustments to the laser treatment area and energy, incision location and amount of tissue to be removed. It refers to individual planning for SMILE pro, rather than a procedure that implants a separate lens.
VISUMAX 800 includes CentraLign to help center the treatment and OcuLign to help adjust the astigmatism axis to account for rotation of the eye. These equipment features and your individual surgical plan are distinct. The features do not guarantee the same outcome for every patient; how they are used depends on your examination results and the surgeon’s judgment.
With a short laser exposure time of about 7 seconds, SMILE pro offers the prospect of a quick recovery and excellent quality of vision. However, the time from arriving at the clinic to undergoing surgery can vary. Our SMILE pro guide (in Korean) explains the equipment and BESPOKE SMILE approach.
What should be assessed if you have thin corneas or significant astigmatism?
Corneal thickness alone does not determine which procedure is suitable. The assessment also considers the shape of the cornea and any abnormalities, the prescription to be corrected, the corneal tissue that would remain after surgery, pupil size and the condition of your tear film. Before the examination, tell us about any recent change in your glasses prescription, eye conditions or previous eye surgery.
Everyday difficulties also help guide the choice. Let us know if you experience glare or halos when driving at night, dryness after prolonged screen use, or take part in sports where your eyes could be hit. Rather than choosing a procedure simply because it uses the latest equipment, ask which aspects of your eye condition make it a suitable recommendation.
If corneal vision correction is unsuitable, other options such as ICL may be considered. ICL requires its own examination and suitability assessment. Being unable to have SMILE does not automatically make you a candidate for lens implantation.
Which questions should you ask at your consultation?
Discussing these three questions in light of your own examination results can help you make a more informed choice than comparing procedure names alone.
- Which procedures are suitable for my eyes, which are ruled out, and why?
- What discomfort and side effects might I experience with the recommended procedure, and could I need further correction?
- How can my examination, surgery and follow-up visits fit around my work and return travel plans?
When comparing costs, check whether SMILE and SMILE pro fall under the same fee category, and whether the cost varies depending on the surgeon or any additional services. You can review the currently listed items in SNU Eye Clinic’s fees for services not covered by health insurance (in Korean) and compare them with the quote for the procedure recommended after your examination.
When booking an examination at SNU Eye Clinic, please include the procedure you are interested in, the type of contact lenses you currently wear, your latest prescription and the dates of your stay in Korea. You can request an in-person consultation through our online appointment form (in Korean).
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The notes below are awaiting clinic review. The approval and publication details above apply only to the original article.
What about PRK, LASEK and ICL?
You may also come across PRK and LASEK when comparing laser surgery. These procedures treat the surface of the cornea. ICL works differently: a corrective lens is placed inside the eye. Our ICL and SMILE comparison explains the differences in treatment and the examinations you will need.
Sources: ZEISS: comparison of vision correction procedures · FDA: phakic intraocular lenses
What do studies tell us about SMILE pro results?
A 2024 study compared 50 eyes treated with VISUMAX 800 and 100 treated with VISUMAX 500, using matched patient records. Vision and prescription results were similar through six months. The study also found a difference in induced higher-order aberrations, a measure of optical distortion. Your own examination results and treatment plan are needed to interpret what these group findings mean for you.
For your consultation, consider which outcomes matter in daily life: early recovery, your final prescription, comfort and night vision. Discuss these alongside the study's starting prescriptions and follow-up period. Laser treatment time is only one part of the procedure.
What are the risks of SMILE?
Possible problems after SMILE include dry-eye symptoms, glare or halos, undercorrection or overcorrection, and infection. A rare complication called corneal ectasia causes progressive weakening and changes in the shape of the cornea. Ask how your examination results affect these risks and what follow-up or further treatment you might need.
Reading an eye chart well does not tell the whole story, especially when it comes to comfort and night driving. Tell your ophthalmologist about your work and any difficulties with night vision.
What can equipment specifications and research tell you?
Equipment specifications explain what a device does. Regulatory approvals describe its permitted use in a particular country, while clinical studies report results in the patients who took part. Each answers a different question.
When reading an FDA document, check the device model, approval or supplement date, and the conditions it was approved to treat. An older US label or a number in a search result may not apply to treatment in Korea. Your ophthalmologist can explain how the equipment's approved use in Korea relates to your examination results.
Sources: ZEISS: VISUMAX 800 and SMILE pro · 2024 clinical comparison of VISUMAX 800 and 500
SNU EYE CLINIC
SMILE experience and teaching at SNU
Chung Eui Sang’s medical background, SMILE interview and academic activities.
Medical Director
Chung Eui Sang정의상
Doctorate in Medicine, Seoul National University. Previously a professor at Samsung Medical Center and a research professor at the Schepens Eye Research Institute, Harvard Medical School.
View the official profile · KoreanA conversation about SMILE
Chung Eui Sang took part in ZEISS Expert Talk 2025, discussing his experience with refractive surgery. The interview is published by ZEISS, the equipment manufacturer.
Read the ZEISS interview
Before you book
Discuss SMILE and SMILE pro at SNU
Tell us your recent prescription, contact lens type and everyday visual needs. Ask about the examination needed to compare SMILE, SMILE pro and LASIK for your eyes.
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