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LASIK vs SMILE vs SILK: SMILE Pro vs ReLEx SMILE vs Femto-LASIK
LASIK vs SMILE vs SILK is mostly a choice between a flap and no flap, and all three give similar vision at three months. Femto-LASIK recovers fastest; SMILE and SILK remove a lens-shaped disc through a small opening and tend to cause less dry eye. SMILE Pro is SMILE on the newer VisuMax 800, which shapes the disc in about 10 seconds instead of 28. Prof. Dr. Ahmet Satıcı or Op. Dr. Aysan Bayram recommends one after scanning your eyes.
LASIK vs SMILE vs SILK: how do the three methods differ?
LASIK, SMILE and SILK all correct short sight and astigmatism by changing the curve of the cornea, the clear window at the front of the eye, and the Royal College of Ophthalmologists (RCOphth) says their risks and benefits are similar. The difference is how the surgeon reaches the tissue that is reshaped.
- LASIK (Femto-LASIK). A femtosecond laser cuts a thin protective flap, the surgeon lifts it, a second laser (an excimer laser) removes a lens-shaped piece of tissue from beneath, and the flap is smoothed back without stitches. "Femto" means the flap is cut by laser rather than by a blade.
- SMILE (small incision lenticule extraction). One femtosecond laser outlines a lens-shaped disc of tissue, called a lenticule, inside the cornea. The surgeon lifts the lenticule out through a small opening of about 2–3 mm, according to the American Academy of Ophthalmology's EyeWiki. There is no flap and no second laser. The RCOphth describes it as "like LASIK without the LASIK flap".
- SILK (smooth incision lenticular keratomileusis). Another lenticule-extraction procedure, performed on a different manufacturer's laser (the ELITA), with a differently shaped lenticule. It is newer than SMILE, which has been performed since 2008, with at least six million procedures worldwide according to a 2025 study. In a 6-month study of 170 eyes, 96% reached 20/20 or better without glasses, and the authors judged it safe and effective for short sight with or without astigmatism. We include SILK here because many people search for all three names together; it is not the focus of this page.
| Femto-LASIK | SMILE / SMILE Pro | SILK | |
|---|---|---|---|
| Lasers used | Femtosecond (flap) + excimer (reshaping) | One femtosecond laser | One femtosecond laser (ELITA) |
| Access to the tissue | A thin flap is lifted | A small opening, about 2–3 mm | A small opening |
| What is removed | Tissue is ablated (vaporised) under the flap | A lenticule is lifted out | A biconvex lenticule is lifted out |
| Treats | Short sight, long sight, astigmatism | Mainly short sight with astigmatism | Short sight with or without astigmatism |
| Track record | Long established, large evidence base | Since 2008 | Newer; CE-marked in March 2023 |
Sources: RCOphth patient information; EyeWiki (KLEx and SMILE pages); Davis et al. 2025; Sachdev et al. 2023; Johnson & Johnson Vision press release, 1 March 2023.
Our lenticule procedure is SMILE Pro. If you want the treatment page rather than the comparison, see SMILE Pro in Istanbul (VisuMax 800).
What is the difference between ReLEx SMILE and SMILE Pro?
SMILE Pro eye surgery is SMILE performed on the newer ZEISS VisuMax 800 laser, and ReLEx SMILE is the name many clinics and patients still use for the original procedure on the older VisuMax 500. The principle is identical: one femtosecond laser, one lenticule, one small opening, no flap.
Where the names come from. ReLEx stands for refractive lenticule extraction; SMILE stands for small incision lenticule extraction. EyeWiki traces the family back to femtosecond lenticule extraction in 2007, then ReLEx, then the smaller-incision SMILE. Doctors now use the umbrella term keratorefractive lenticule extraction (KLEx) for all of them.
| ReLEx SMILE (VisuMax 500) | SMILE Pro (VisuMax 800) | |
|---|---|---|
| Laser pulse rate | 500 kHz | 2,000 kHz (2 MHz) |
| Time to create the lenticule | 28.3 seconds on average | 10.3 seconds on average |
| Centring | Manual, by the surgeon | Automated aid (CentraLign) |
| Correction for eye rotation (cyclotorsion) | Manual | Automated tool (OcuLign) |
| Average decentration of the treatment | 0.41 mm | 0.22 mm |
| Visual results at 3 months | Excellent | Comparable (no significant difference in efficacy or safety) |
Timing, pulse rate and decentration: Kim and Chung, Scientific Reports 2025, 100 eyes per group. Features: EyeWiki. In that study the VisuMax 800 group used CentraLign but not OcuLign.
In the United States, SMILE received US Food and Drug Administration (FDA) approval in 2016 for short sight and in October 2018 for astigmatism, for people aged 22 and over. SMILE Pro on the VisuMax 800 was FDA-approved in 2024, as reported in a 2025 comparison study.
What changed with the VisuMax 800, and does it improve results?
The VisuMax 800 makes the laser step about three times faster and centres the treatment more accurately, but three-month visual results are similar to the older laser. That is what the comparison studies published so far show.
Speed
In the Kim and Chung study (Scientific Reports, 2025), the lenticule took 10.33 seconds on the VisuMax 800 and 28.27 seconds on the VisuMax 500. That means less time with the suction ring on your eye and less time you have to stay perfectly still. EyeWiki puts the VisuMax 800 laser time at about 8–10 seconds.
Centring
The same study found the average decentration of the treatment was 0.22 mm on the VisuMax 800 against 0.41 mm on the VisuMax 500, a statistically significant difference. Good centring matters most for astigmatism and for night vision.
Eye tracking and rotation compensation
A 2025 study in Cureus of 87 eyes (Davis et al.) describes an eye-tracking system, cyclotorsion compensation and a reduction in total higher-order aberrations as the main hardware changes. In that study all eyes on both lasers saw 20/40 or better at three months, with no significant difference in safety or efficacy.
Two large SMILE Pro series
In 765 eyes treated on the VisuMax 800 (Vietnam, 2025), 92% saw 20/25 or better without glasses at three months, 81% were within ±0.50 D of the intended prescription, and 99% had no change in best-corrected vision. In a German series of 152 eyes (2024), 91% were within ±0.50 D, no eye lost more than one line of best-corrected vision, and all 18 highly short-sighted eyes (−6.25 to −10.00 D) reached 20/20.
What this means for you. The VisuMax 800 is a refinement, not a different operation. A shorter, better-centred laser step is a real practical gain, but the studies are short (three months) and small, and we found no head-to-head trial showing that the final result after SMILE Pro is better than after ReLEx SMILE. Long-term follow-up so far comes from SMILE on earlier lasers. One 10-year study of 208 eyes found 84.6% still saw 20/20 or better, and the average prescription had drifted from −0.11 D at 3 months to −0.28 D at 10 years; the authors found no significant decrease in their safety index, although 15 eyes (7.2%) had lost two lines of corrected vision. SMILE Pro has the same biology and the same limits as SMILE.
Is SMILE better than Femto-LASIK?
Neither is better for everyone: in the best evidence, visual results are the same, and the differences lie in recovery, dry eye and which eyes each suits. The RCOphth states that visual results at three months are equally good for all types of laser vision correction.
- Vision results. A meta-analysis of 12 studies and 1,076 eyes (Shen et al., PLoS One 2016) found no significant difference between SMILE and femtosecond LASIK in the chance of 20/20 vision, in predictability or in loss of best-corrected vision. EyeWiki reports that at 12 months 85% of SMILE eyes and 83% of femtosecond-LASIK eyes saw 20/20 or better without glasses.
- Dry eye. Dry eye is the most common side effect of all laser eye surgery, but it is usually milder after SMILE. EyeWiki cites a tear break-up time that was about 3.3 seconds longer after lenticule extraction than after LASIK at both 3 and 6 months, and the Shen meta-analysis found lower dry-eye symptom scores and better corneal sensitivity after SMILE. The RCOphth adds that the differences between techniques are small, and that mild eye-surface discomfort is normal early on after all of them.
- Corneal strength. The front layer of the cornea carries about 60% of its tensile strength, and EyeWiki notes that SMILE preserves corneal biomechanics better than LASIK, which cuts across that layer. Ectasia (a weakening and bulging of the cornea) remains rare after both when screening is done properly: the RCOphth says that fewer than 1 in 5,000 patients need a corneal transplant to restore vision after any laser vision correction.
- Tissue removed. The RCOphth notes that lenticule extraction removes slightly more tissue than LASIK, from slightly deeper in the cornea, which is one reason it needs a cornea of good thickness.
- Extra treatment. Up to 1 in 10 patients need some additional surgery to get the best result after any laser method (RCOphth). After LASIK, the flap can be lifted again. After SMILE, a touch-up is usually done with surface laser, or by converting the cap to a flap with special software on the VisuMax platform, which EyeWiki notes is not FDA-approved in the US.
- Flap-related issues. Femtosecond flaps are very predictable, and EyeWiki notes they significantly reduce blade-related problems such as buttonholes and free caps. They can still cause transient light sensitivity, rainbow glare and interface inflammation. SMILE has no flap, so none of these apply, but it has its own issues, such as suction loss during the laser step (re-applied in the same session in 81.8% of cases, according to EyeWiki).
SMILE vs LASIK recovery time: which is faster?
LASIK usually gives the fastest visual recovery, SMILE is slightly slower, and surface laser is the slowest. The RCOphth says LASIK patients are often able to return to work the day after surgery, visual recovery after lenticule extraction may be slightly slower, and surface laser patients may need a week or longer before they reach the driving standard.
| Femto-LASIK | SMILE / SMILE Pro | PRK / no-touch laser | |
|---|---|---|---|
| Visual recovery | Fastest; often back to work the next day | Slightly slower | Slowest; a week or longer before driving standard |
| Eye-surface comfort | Mild discomfort in the early period | May recover slightly faster | Normally very sore while the surface skin regrows (about a week) |
| Contact sports | Wait at least 1 month | Sooner than LASIK | Sooner than LASIK |
| Showering and washing | Normally from day one | Normally from day one | After the bandage lens is removed (typically day 4 to 7) |
| Gym and jogging | From day one | From day one | From day one (RCOphth, all methods) |
Source: RCOphth patient information. Swimming is usually not advised for a week after any of them.
For all methods, vision keeps settling for months. The FDA notes that it can take three to six months for vision to stabilise after LASIK, with fluctuation, glare and halos during that time; the RCOphth says most prescription changes after three months are very small but full stabilisation can take up to two years. Red patches on the white of the eye are common, especially after LASIK, and can take up to 6 weeks to fade. Most patients fly home 1–3 days after laser surgery, once their surgeon has checked their eyes.
LASIK vs SMILE for astigmatism: is one more accurate?
Both treat astigmatism, but the evidence leans slightly towards LASIK being more precise, and the gap is small. SMILE was first approved for short sight alone and received US approval for astigmatism in October 2018.
- For low to moderate astigmatism (up to 2.00 D), EyeWiki reports that SMILE had a smaller correction index and a larger difference vector than LASIK, which means slightly less accurate astigmatism correction.
- For higher astigmatism (2.00 D or more), a meta-analysis of six studies and 485 eyes (Cui et al., Frontiers in Medicine 2023) found the same uncorrected vision after SMILE and femtosecond LASIK, but slightly more residual astigmatism after SMILE (0.07 D on average). The authors link this to the lack of control for eye rotation during SMILE, and SMILE induced less spherical aberration than the excimer-based methods.
- The VisuMax 800 was designed to address exactly this, with its automated rotation-compensation tool (OcuLign). The studies above were not designed to test that tool, and in the one 100-eye VisuMax 800 comparison we reviewed it was not used, so we cannot yet say how much it closes the gap.
What this means for you. If you have astigmatism, ask your surgeon how much you have, which method gives the most predictable result for your numbers, and what the plan would be for a touch-up. For astigmatism alone, with no short sight to correct, SMILE is not the usual choice.
Custom LASIK vs SMILE: what about topography-guided and wavefront-guided LASIK?
"Custom LASIK" means LASIK in which the excimer laser follows a measurement of your own eye rather than a standard pattern. There are three common versions: wavefront-optimised (corrects for the average optical error of the laser itself), wavefront-guided (follows a map of your eye's optical aberrations) and topography-guided (follows a map of the surface shape of your cornea).
EyeWiki's review reports no evidence of a difference between wavefront-guided and corresponding conventional procedures, and that topography-guided treatment achieved a higher proportion of eyes within ±0.50 D of target than wavefront-optimised treatment in the trial it cites. That makes topography-guided LASIK a useful option for eyes with irregular corneas or for retreatments, and a choice that depends on what your scans show.
SMILE works differently: it removes a lenticule whose shape is calculated from your prescription, so there is no equivalent "custom pattern" setting. For most people with a regular cornea and a simple prescription, both routes end in similar vision; custom LASIK is mostly a question for people with irregular corneas, higher-order aberrations or a previous treatment. Some platforms are sold under brand names, so ask your surgeon which laser they use and what published evidence supports it.
LASIK vs SMILE vs PRK: where does surface laser fit?
In a SMILE vs LASIK vs PRK comparison, PRK (and no-touch laser, Trans-PRK) is the third main way to reshape the cornea, and it is the one with no flap and no incision at all. The surgeon removes the thin surface layer first (or the laser does it, in no-touch Trans-PRK), reshapes the tissue beneath, and the surface skin regrows over about a week. The RCOphth says Trans-PRK shortens the recovery by 1 to 2 days compared with PRK.
The American Academy of Ophthalmology says PRK may be a good choice if your corneas are thin, since LASIK is not recommended in that case, and for active people, because there is no flap. The cost is comfort: for 2 to 3 days there may be eye pain, vision improves over 3 to 5 days, and it can take a month or longer to reach your best vision. In the long run the results are similar.
SMILE vs LASIK cost: which is more expensive?
SMILE usually costs more than Femto-LASIK, at home and in Istanbul, because of the laser platform it needs. The ranges below are typical published prices for both eyes in 2025–26, not quotes.
| Both eyes | UK private clinics | Germany private clinics | USA | Istanbul (published prices) | Laser Istanbul Clinic |
|---|---|---|---|---|---|
| Femto-LASIK | £3,000–5,600 | €2,400–4,600 | $4,000–6,000 | about $1,450–2,700 | from {{£ price}} |
| SMILE / SMILE Pro | £4,400–7,600 | €2,800–5,200 | $5,000–8,000 | about $2,000–3,450 | from {{£ price}} |
Ranges published by clinics and price-comparison sites in 2025–26. Published Istanbul prices are often packages that include a hotel; our price covers your medical treatment so you can compare like for like.
At Laser Istanbul Clinic your price includes your pre-operative examination and scans, surgery by your named surgeon, medication, follow-up checks in Istanbul, a personal interpreter, a coordinator and remote follow-up. Hotel and airport transfers are not included; they are a separate charge, arranged on request. Flights are not included. In the UK, the RCOphth notes that laser vision correction is not available on the NHS and is not covered by private health insurance, and that a clinic's price should normally include follow-up visits and any fine-tuning laser treatments for up to two years.
Which is right for you: Femto-LASIK, SMILE Pro or PRK?
The right method is the one that suits your corneal thickness, prescription, lifestyle and age, and your surgeon decides after measuring your eyes. These are the usual tendencies.
| Your situation | Often considered | Why |
|---|---|---|
| You play contact or combat sports | SMILE Pro or PRK | No flap; contact sports resume sooner than after LASIK (RCOphth) |
| Your eyes tend to be dry | SMILE Pro or PRK | Less dry eye after SMILE; fewer nerves cut |
| You want the fastest visual recovery | Femto-LASIK | Often back at work the next day (RCOphth) |
| You are long-sighted | Femto-LASIK or PRK | SMILE is mainly used for short sight; EyeWiki notes it is not FDA-approved for long sight |
| You have a significant amount of astigmatism | Femto-LASIK, or SMILE Pro after discussion | Slightly more predictable astigmatism correction with LASIK in the studies above |
| Your corneas are thin | PRK or no-touch laser | LASIK is not recommended with thin corneas (AAO); lenticule extraction also removes slightly more tissue |
| You are in your mid-40s or older | Discuss lens surgery | From the mid-40s, lens replacement may be better than laser; the RCOphth notes it is often preferred in the retirement age group where early cataract is common |
Who should not have any of them. The usual reasons to be turned away from corneal laser are keratoconus or an abnormal corneal shape, an unstable prescription, severe dry eye or eye-surface disease, and pregnancy or breastfeeding (EyeWiki). Your surgeon may then suggest an implantable lens or lens surgery instead. The RCOphth says you must be over 18 with a prescription that has changed by no more than 0.5 D in two years, and that laser is most likely suitable up to −10.00 D of short sight, +4.00 D of long sight and ±6.00 D of astigmatism.
Before your examination, leave your contact lenses out so your cornea returns to its natural shape. The FDA advises at least 2 weeks for soft lenses, 3 weeks for toric soft or rigid gas-permeable lenses and 4 weeks for hard lenses; your coordinator confirms the timing for your lenses.
Frequently asked questions
LASIK cuts a flap and reshapes the cornea underneath with a second laser. SMILE and SILK use a single femtosecond laser to shape a thin lens-shaped disc inside the cornea, which the surgeon lifts out through a small opening, with no flap. SMILE and SILK differ in the laser used and the shape of the disc. Vision results at three months are similar for all of them.
Not for everyone. Meta-analyses show no significant difference in the chance of 20/20 vision between SMILE and femtosecond LASIK. SMILE tends to cause less dry eye and lets you return to contact sports sooner; LASIK recovers a little faster and treats long sight as well.
Both remove a lenticule through a small opening with no flap. SMILE Pro uses the newer ZEISS VisuMax 800, which creates the lenticule in about 10 seconds instead of about 28 and has automated aids for centring and eye rotation. Studies show similar visual results at three months, with better centring on the VisuMax 800.
SMILE Pro is SMILE performed on the VisuMax 800 laser. It is the same procedure with a newer machine, not a different type of surgery. Its benefits and limits are those of SMILE.
Both can correct astigmatism. In the studies we reviewed, LASIK was slightly more accurate for astigmatism, particularly above 2.00 D, because SMILE has historically had less control over eye rotation. The VisuMax 800 includes a tool for this, but head-to-head evidence is still limited, so ask your surgeon to explain the plan for your numbers.
LASIK. Many people are back at work the day after LASIK, and the RCOphth says recovery after lenticule extraction may be slightly slower. After SMILE, contact sports can restart sooner than after LASIK, where you wait at least a month.
SMILE is usually better. Fewer corneal nerves are cut, and meta-analyses find longer tear break-up time and better corneal sensation after SMILE than after LASIK. Dryness still happens after SMILE, and it is treated with lubricating drops. If your eyes are already dry, your surgeon will test your tear film first.
Usually yes. UK private clinics typically charge £4,400–7,600 for SMILE and £3,000–5,600 for Femto-LASIK, both eyes. At Laser Istanbul Clinic, SMILE Pro starts from {{£ price}} for both eyes; hotel and transfers are extra, and your exact price is confirmed in writing after your free assessment.
SMILE itself is rarely repeated. If you need fine-tuning, it is usually done with surface laser or by converting the cap into a flap, provided enough corneal thickness remains. Up to 1 in 10 laser patients need some additional surgery. Our policy: {{enhancement / re-treatment policy and the period it covers}}.
The reshaping is permanent. In a 10-year study of 208 SMILE eyes, 84.6% still saw 20/20 or better, and the average prescription had changed by about 0.16 D between 3 months and 10 years. Your eyes still age, and reading glasses in your 40s or 50s come from the natural lens, not from laser wearing off.
Not sure whether SMILE Pro, LASIK or PRK suits your eyes?
At Laser Istanbul Clinic, Prof. Dr. Ahmet Satıcı or Op. Dr. Aysan Bayram measures your corneas, tear film and prescription before recommending anything, and tells you honestly if laser is not right for your eyes. Surgery takes place in a fully equipped, Ministry of Health–licensed operating theatre in Istanbul. Send your prescription and scans and we will reply with a written plan and price.
Sources for the facts on this page
- The Royal College of Ophthalmologists. Laser Vision Correction: patient information (PROF/2024/499). https://www.rcophth.ac.uk/wp-content/uploads/2026/08/Laser-vision-correction-patient-information.pdf (linked from https://www.rcophth.ac.uk/guidance-resources/laser-vision-correction/)
- EyeWiki (American Academy of Ophthalmology). Small Incision Lenticule Extraction (SMILE). https://eyewiki.org/Small_Incision_Lenticule_Extraction_(SMILE)
- EyeWiki (AAO). Keratorefractive Lenticule Extraction (KLEx) Surgeries. https://eyewiki.org/Keratorefractive_Lenticule_Extraction_(KLEx)_Surgeries
- EyeWiki (AAO). LASIK for Myopia and Astigmatism: Safety and Efficacy. https://eyewiki.org/LASIK_for_Myopia_and_Astigmatism:_Safety_and_Efficacy
- EyeWiki (AAO). Femtosecond Lasers and Laser Assisted in Situ Keratomileusis (LASIK). https://eyewiki.org/Femtosecond_Lasers_and_Laser_Assisted_in_Situ_Keratomileusis_(LASIK)
- Kim BK, Chung YT. Comparison of clinical outcomes following small incision lenticule extraction performed with the VisuMax 800 versus VisuMax 500 femtosecond laser. Scientific Reports 2025;15:25484. https://pmc.ncbi.nlm.nih.gov/articles/PMC12264011/
- Davis JC, Sitto MM, Herrera E, Palmer BL, Hoopes P, Moshirfar M. Comparison of Initial Visual Outcomes Following Keratorefractive Lenticule Extraction (KLEx) Using VisuMax 500 Versus VisuMax 800. Cureus 2025;17(8):e89702. https://pmc.ncbi.nlm.nih.gov/articles/PMC12417058/
- Cung HS, Tran LHT, Tran TN. Three-Month Outcomes of SMILE Pro with the VISUMAX 800 for Myopic Astigmatism in a Large Population. Clinical Ophthalmology 2025;19:417–425. https://pmc.ncbi.nlm.nih.gov/articles/PMC11812556/
- Saad A, Klabe K, Kirca M, Kretz FAT, Auffarth G, Breyer DRH. Refractive outcomes of small lenticule extraction (SMILE) Pro with a 2 MHz femtosecond laser. International Ophthalmology 2024;44:52. https://pmc.ncbi.nlm.nih.gov/articles/PMC10858925/
- Ten-year evaluation on efficacy, safety, and predictability of femtosecond laser corneal small incision lenticule extraction for correction of myopia and myopic astigmatism: a case series (208 eyes). Annals of Medicine and Surgery 2024. https://pmc.ncbi.nlm.nih.gov/articles/PMC11543156/
- Shen Z, Shi K, Yu Y, Yu X, Lin Y, Yao K. Small Incision Lenticule Extraction (SMILE) versus Femtosecond Laser-Assisted In Situ Keratomileusis (FS-LASIK) for Myopia: A Systematic Review and Meta-Analysis. PLoS One 2016;11:e0158176. https://pmc.ncbi.nlm.nih.gov/articles/PMC4930219/
- Cui G, Di Y, Yang S, Chen D, Li Y. Efficacy of small-incision lenticule extraction surgery in high astigmatism: A meta-analysis. Frontiers in Medicine 2022;9:1100241 (published 19 Jan 2023). https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.1100241/full
- Sachdev MS, Shetty R, Khamar P, et al. Safety and Effectiveness of Smooth Incision Lenticular Keratomileusis (SILK) Using the ELITA Femtosecond Laser System for Correction of Myopic and Astigmatic Refractive Errors. Clinical Ophthalmology 2023;17. https://www.dovepress.com/safety-and-effectiveness-of-smooth-incision-lenticular-keratomileusis--peer-reviewed-fulltext-article-OPTH
- Johnson & Johnson Vision. Press release, 1 March 2023: ELITA Femtosecond Laser System receives CE Mark. https://jjvision.com/press-release/johnson-johnson-vision-receives-ce-mark-approval-new-corneal-refractive-technology
- American Academy of Ophthalmology. What Is Photorefractive Keratectomy (PRK)? https://www.aao.org/eye-health/treatments/photorefractive-keratectomy-prk
- US Food and Drug Administration. LASIK: What should I expect before, during, and after surgery? https://www.fda.gov/medical-devices/lasik/what-should-i-expect-during-and-after-surgery