SMILE eye surgery is a laser vision correction procedure that reshapes the cornea through a tiny incision, typically less than 4 millimeters wide. Unlike LASIK, which requires cutting a large flap in the cornea, SMILE works through a small keyhole opening, making it a less invasive option for people with nearsightedness and astigmatism. The procedure was FDA-approved in 2016 and has become one of the fastest-growing alternatives to LASIK worldwide.
How the Procedure Works
SMILE stands for Small Incision Lenticule Extraction. The entire procedure relies on a single laser, called a femtosecond laser, which delivers ultrashort pulses of infrared light to a precise depth inside the cornea. These pulses outline a thin, disc-shaped piece of tissue called a lenticule. The shape and thickness of this lenticule are calculated beforehand based on your prescription.
Once the laser finishes, your surgeon opens a small side incision in the cornea’s surface, separates the lenticule from the surrounding tissue, and pulls it out through that opening. Removing this tiny piece of tissue changes the curvature of your cornea, redirecting light so it focuses correctly on your retina. With newer laser platforms like the ZEISS VisuMax 800, the laser portion takes less than 10 seconds per eye.
The key difference from LASIK is what doesn’t happen. There’s no large corneal flap (typically 20 millimeters in circumference with LASIK) and no second laser to vaporize tissue. This means fewer corneal nerves are severed during surgery, which has meaningful consequences for recovery.
What SMILE Can and Cannot Correct
SMILE is FDA-approved to treat nearsightedness (myopia) between -1.00 and -8.00 diopters, and astigmatism up to 3.00 diopters. If your prescription falls outside those ranges, or if you’re farsighted, SMILE isn’t currently an option. LASIK or another procedure would be more appropriate.
Beyond prescription limits, your corneas need to be thick enough to safely remove the lenticule while leaving enough structural tissue behind. The general minimum corneal thickness is about 475 micrometers. Surgeons also calculate how much residual tissue remains after the procedure to ensure the cornea stays stable long-term. Conditions like keratoconus (where the cornea is already thinning and bulging) or autoimmune diseases that affect healing are disqualifying factors.
If you wear contact lenses, you’ll need to stop wearing them before your pre-operative evaluation so your cornea returns to its natural shape. For soft lenses, that’s typically three weeks. For gas permeable (hard) lenses, plan on four weeks.
Why Dry Eye Is Less Common Than With LASIK
Dry eye is one of the most common complaints after any laser vision surgery, and it’s the area where SMILE shows the clearest advantage over LASIK. The reason comes down to anatomy. LASIK requires cutting a flap across most of the cornea’s surface, which severs a large number of the nerves responsible for sensing dryness and triggering tear production. With SMILE’s small incision, far fewer of those nerves are disrupted.
Studies comparing the two procedures consistently show that corneal sensitivity recovers faster after SMILE. At one month post-surgery, SMILE patients had measurably better corneal sensation than LASIK patients. By six months, the difference between the two groups leveled out, but that early recovery window matters. LASIK patients often experience corneal sensitivity that hasn’t fully returned to pre-operative levels even at six months.
Tear film stability, measured by how quickly the tear layer breaks apart between blinks, drops after both procedures. But SMILE patients generally report fewer dry eye symptoms and show better tear production numbers during recovery. If you already deal with borderline dry eyes, this distinction could influence which procedure your surgeon recommends.
Recovery Timeline
Most people notice clearer vision immediately after SMILE, though some initial blurriness is normal and improves over the first few days. By two to three days post-surgery, vision is typically clear enough to drive, return to work, and handle longer sessions of reading or screen time. You can also resume wearing eye makeup at that point.
The physical recovery milestones follow a predictable schedule:
- Day after surgery: Return to work, shower carefully (keeping water away from your eyes)
- 2 to 3 days: Driving, normal computer use, showering without restrictions
- 1 week: Light exercise and noncontact sports
- 4 to 6 weeks: Swimming, water activities, and contact sports
The longer wait for swimming and contact sports protects the small incision site while it finishes healing. Even though the incision is far smaller than a LASIK flap, it still needs time to seal completely before exposure to pool water, ocean water, or the risk of a direct hit to the eye.
Visual Outcomes and Success Rates
A five-year study tracking patients who had SMILE for high myopia found that 73% achieved 20/20 vision or better, and 97% achieved 20/25 or better. Those results held steady at the five-year mark, which is an important indicator of long-term stability. Regression, where your prescription gradually creeps back, is a concern with any refractive surgery, but the data suggests SMILE results remain durable over time.
These numbers are specifically from patients with high prescriptions, where outcomes are generally harder to achieve. Patients with moderate myopia tend to see even higher rates of 20/20 results.
Risks and Complications
The most serious rare complication is corneal ectasia, a progressive weakening and bulging of the cornea that can significantly affect vision. A large study of over 6,600 SMILE eyes found an ectasia rate of 0.15%, occurring on average about 21 months after surgery. Nearly all cases occurred in eyes that were already considered borderline candidates before surgery. Among those borderline eyes specifically, the ectasia rate was 0.80%, while eyes that received a supplemental corneal strengthening treatment at the time of surgery had a 0% ectasia rate.
More common but temporary side effects include halos and glare around lights at night, which are typical of all corneal refractive surgeries and generally diminish as the cornea heals over the first few months. Some patients also experience mild discomfort or a gritty sensation for a day or two after surgery, though this tends to be less intense than what LASIK patients report because of the smaller incision.
How SMILE Compares to LASIK
Both procedures reshape the cornea to correct vision, and both achieve excellent visual outcomes. The practical differences come down to the approach and its consequences. LASIK uses two lasers: one to create a hinged flap, another to reshape the exposed tissue. SMILE uses a single laser and a small incision. This makes SMILE structurally gentler on the cornea, preserving more of its biomechanical strength.
LASIK still has some advantages. It can treat farsightedness, which SMILE cannot. It also allows for easier enhancement procedures if a touch-up is needed, because the original flap can be re-lifted. SMILE enhancements are more complex and sometimes require a different approach entirely. Visual recovery with LASIK can also be slightly faster in the first 24 hours, though the difference is minimal and evens out within days.
For candidates who qualify for both, the choice often comes down to prescription range, dry eye risk, and surgeon preference. People with a history of dry eyes, those who play contact sports, or those uncomfortable with the idea of a corneal flap tend to lean toward SMILE. People with farsightedness or mixed prescriptions outside SMILE’s approved range will be better served by LASIK or a surface procedure like PRK.