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SMILE Laser Vision Correction

By Craig S. Bindi, MD

After performing over 50,000 refractive surgeries, including LASIK and its refractive variations Epi-LASIK/PRK, Visian ICL, Raindrop Inlay, Kamra Inlay, and SMILE, I’ve learned that each technique has its unique role in treating specific vision problems. On this page, I describe the SMILE procedure, and its distinct advantages and limitations compared to LASIK/Epi-LASIK. The SMILE procedure represents “another tool in our toolbox” for helping my patients achieve a lens-free lifestyle.

Summary of SMILE:

SMILE is an FDA-approved laser vision correction procedure to treat pure nearsightedness without visually-significant astigmatism (0.50 D or less astigmatism). The VisuMax laser is the only femtosecond laser that is approved for the SMILE procedure, which is a minimally-invasive, bladeless, painless, flapless, single-step laser procedure to treat nearsightedness. But for patients with visually-significant astigmatism or farsightedness, LASIK and Epi-LASIK/PRK are more effective options than SMILE. During your consultation, I will be able to determine the best refractive option for you.

What’s it like to undergo the SMILE procedure? 

Prior to the procedure, numbing eye drops are instilled and an oral sedation pill is offered to minimize anxiety. Similar to LASIK, the SMILE procedure takes about 15 minutes to complete for both eyes. Fortunately, patients typically “feel nothing” during the SMILE procedure, but eyes may feel scratchy and irritated for a few hours after SMILE.  Patients can expect to have “functional vision” and return to work the next day, but it can take a few days before vision seems “very clear”. Afterward, antibiotics, anti-inflammatory and lubrication eye drops are used to promote rapid healing.

Animated video of the SMILE procedure:

Specifically, how does SMILE treat nearsightedness?

For SMILE, I use the same femtosecond laser that I typically use for LASIK (the VisuMax femtosecond laser), but with a few distinct differences. During the SMILE procedure, the VisuMax laser sculpts a thin lens-shaped “refractive lenticle” that corresponds to one’s optical correction (red area seen below). Simultaneously, the VisuMax laser creates a 4-millimeter micro-opening so the refractive lenticle can be removed. For patients with a larger amount of nearsightedness, the refractive lenticle will be thicker compared to a mild correction. Unlike LASIK, the SMILE procedure does not use a wavefront excimer laser, just the VisuMax femtosecond laser. SMILE is an abbreviation for “SMall Incision Lenticule Extraction and it is analogous to “slipping out a contact lens-shaped lenticle from the cornea”.  

Who is a good candidate for SMILE? 

  • Age 22 years or older
  • Myopia from -1.00D to -8.00D with no more than -0.50D of astigmatism. Generally, patients that are happy with soft contact lenses that don’t treat for astigmatism (soft non-toric contact lenses)
  • Relatively stable glasses prescription in the last 12 months
  • Normal topography and corneal thickness (similar to what is required for LASIK)
  • No previous eye surgery
  • Good general and eye health
  • Not pregnant

FYI: In a retrospective analysis consisting of 200,000 patients that were interested in having a laser vision correction procedure between 2015-2017, approximately 30% of patients were within the FDA-approved treatment range for SMILE. The remainder of patients were either too nearsighted (>-8.0 D), or had farsightedness, or had visually-significant astigmatism (>0.5 D astigmatism) for SMILE. Conversely, about 93% of patients are within the FDA approved treatment range for LASIK/Epi-LASIK, which includes -12.0 diopters nearsightedness, +6.0 diopters of farsightedness, and 6.0 diopters of astigmatism.

The following features that differentiate SMILE from LASIK/Epi-LASIK/PRK:

  1. Unlike LASIK, a corneal “flap” is not created in either SMILE or Epi-LASIK/PRK. Though corneal flap-related problems are exceedingly rare with modern LASIK, there is no possibility of a flap-related problem if there isn’t a flap. Certain patients that previously weren’t candidates for LASIK due to thin corneas may now be candidates for SMILE.
  2. Unlike Epi-LASIK/PRK procedure, SMILE has a rapid visual recovery and no discomfort during the recovery period (similar to a LASIK recovery).
  3. Compared to LASIK/Epi-LASIK, the SMILE laser treatment avoids the anterior corneal nerves, which function to regulate natural tear production. So, SMILE may have a potential advantage for patients with chronic dry eye problems, compared to LASIK or Epi-LASIK.
  4. Unlike LASIK and Epi-LASIK/PRK, the SMILE procedure is NOT approved to treat ANY astigmatism. SMILE is FDA-approved to treat up to -8.0 diopters of pure nearsightedness without visually significant astigmatism, while LASIK is FDA approved to treat up to -12.0 diopters of nearsightedness and 6.0 diopters of astigmatism. So, LASIK/Epi-LASIK is more appropriate for patients that have more than 0.50 astigmatism or pre-existing night vision problems due to high order” aberrations.
  5. Since 1998, LASIK and Epi-LASIK/PRK have been FDA-approved for treating nearsightedness, farsightedness and astigmatism. The first SMILE procedure was performed in 2008 and SMILE technology has been improved and refined ever since. SMILE became FDA-approved in the United States in 2016 after long term studies demonstrated that SMILE is safe and effective option for treating pure nearsightedness.
  6. After having a SMILE procedure, if a laser re-treatment is desired in the future, it is usually possible to have an Epi-LASIK laser re-treatment. SMILE is not approved for re-treatments or fine-tuning residual nearsightedness.
  7. When making apples-to-apples comparisons, clinical studies have shown that the final visual outcomes, results and safety are quite similar between LASIK, Epi-LASIK and SMILE.

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