SMILE Laser Eye Surgery
Here are the basics about SMILE laser eye surgery, which gained FDA approval for use in the United States in September 2016.
What is SMILE laser eye surgery?
SMILE is an acronym for SMall Incision Lenticule Extraction (which is a mouthful and not very easy to remember).
In LASIK, a large opening is required to enable the excimer laser to reshape the underlying cornea. In SMILE, only a very small opening is needed (often less than 4 mm) to facilitate removal of the lenticule.
SMILE laser eye surgery is performed using a VisuMax femtosecond laser, which is proprietary technology of Carl Zeiss Meditec.
In the SMILE procedure, the surgeon uses a femtosecond laser to create a small, lens-shaped bit of tissue (lenticule) within the cornea. Then, with the same laser, a small arc-shaped incision is made in the surface of the cornea, and the surgeon extracts the lenticule through this incision and discards it.
With the tiny lenticule removed, the shape of the cornea is altered, correcting nearsightedness. The corneal incision heals within a few days without stitches, and sharper vision occurs very quickly.
SMILE laser eye surgery can correct up to -10.00 diopters (D) of nearsightedness. Candidates must be at least 22 years old, have no more than -0.50 D of astigmatism, and their eyeglass prescription must be stable for at least 12 months.
To date, more than 1.5 million SMILE procedures have been performed worldwide, according to Carl Zeiss Meditec.
SMILE benefits and advantages
Research is showing SMILE produces virtually the same visual acuity as LASIK for the correction of nearsightedness, without the need to create a LASIK-style corneal flap.
In one study of 328 people who underwent the SMILE procedure, all but one had uncorrected visual acuity (UCVA) of 20/40 or better after surgery, and 88 percent had UCVA of 20/20 or better.
Research suggests there may be less risk of dry eyes after SMILE, compared with after LASIK.
Also, it appears there may be less risk of dry eye symptoms after SMILE, compared with LASIK. There may be several reasons for this, including that because SMILE takes place within the cornea without a large corneal flap, fewer corneal nerves are affected by the procedure.
The very small SMILE incision may also enable the cornea to have more biomechanical stability after SMILE, compared with its ability to maintain shape (especially following trauma) after LASIK.
Finally, for correction of high amounts of nearsightedness, with LASIK there's a greater risk of needing an enhancement procedure to attain the clarity of vision desired without glasses. It appears there is less risk of needing an additional procedure after SMILE for correction of high amounts of myopia, possibly because less dehydration of the cornea occurs during the SMILE procedure.
Limitations of SMILE laser eye surgery
Are there any downsides to SMILE when compared with LASIK or PRK?
For starters, SMILE can only correct nearsightedness, whereas LASIK and PRK can also correct significant amounts of farsightedness and astigmatism.
(The treatment range for SMILE surgery performed in the U.S. will likely be expanded in the future, however. For example, SMILE can be used to treat nearsightedness and up to -5.00 D of astigmatism in Europe.)
Also, LASIK and PRK can treat higher-order aberrations (HOAs) that can affect night vision, whereas SMILE cannot. In fact, SMILE might increase HOAs to some degree.
And if you have residual refractive error after a SMILE procedure and require additional vision correction, typically PRK would be the preferred enhancement procedure for best results.
Finally, as with any newer vision correction surgery, it may be necessary for a surgeon to perform a significant number of SMILE procedures before he or she masters the surgical techniques required for optimum outcomes and minimal risks. Keep this in mind when considering SMILE (versus LASIK or other vision correction procedures) and discussing the procedure with your refractive surgeon.
Cost of SMILE surgery
Most U.S. refractive eye surgeons charge approximately the same price for SMILE laser vision correction as they do for all-laser custom LASIK surgery — somewhere in the range of $2,000 to $3,000 per eye.
A number of factors contribute to the total fee each surgeon charges, including the surgeon's experience, the practice location and whether follow-up exams and additional treatments (if needed) are included.
Is SMILE right for you?
If you are nearsighted and meet the other criteria stated above, you might be a good candidate for SMILE laser vision correction. The next step is to have a comprehensive eye exam with your eye doctor and a consultation with a refractive surgeon.
About the Reviewer: Vance Thompson, MD, FACS, is the director of refractive surgery at Vance Thompson Vision in Sioux Falls, S.D. He also is professor of ophthalmology at the Sanford USD School of Medicine, a leading researcher in technologies for laser and implant vision correction and a member of All About Vision's editorial advisory board.
Page updated December 2018