Femtosecond lenticule extraction versus LASIK draws SMILE
Small incision lenticule extraction (SMILE), which has not yet been approved for refractive correction in the United States, may be less accurate and produce more irregular astigmatism than LASIK or PRK because of the imprecision resulting from the two incisions needed to create the lenticule. In addition, the technique for potential enhancements needs improvement. However, the treatment is promising and may stand the test of time as the technology advances.
Take-home message: Small incision lenticule extraction (SMILE), which has not yet been approved for refractive correction in the United States, may be less accurate and produce more irregular astigmatism than LASIK or PRK because of the imprecision resulting from the two incisions needed to create the lenticule. In addition, the technique for potential enhancements needs improvement. However, the treatment is promising and may stand the test of time as the technology advances.
By Nancy Groves; Reviewed by Steven E. Wilson, MD
Cleveland -
During a SMILE procedure, the femtosecond laser makes two lamellar passes across the cornea that intersect in the peripheral cornea to produce a lenticule with precise dimensions to correct the patient’s refractive error, including myopia, hyperopia, and astigmatism. These two cuts are one of the main reasons why Dr. Wilson has reservations about the technique, although he is not opposed to it.
“It’s important to point out its potential advantages and potential limitations relative to the other procedures that we’re already using, LASIK and PRK,” said Dr. Wilson, professor of ophthalmology, director of corneal research, and cornea and refractive surgery fellowship director, the Cole Eye Institute, Cleveland Clinic.
The precision of the cuts made with the femtosecond laser versus those made with an excimer laser is what concerns him most.
“We have been using the femtosecond laser for many years to make flaps for LASIK, and we know that no two cuts are the same,” Dr. Wilson said. “They all have different OBL (opaque bubble layer) patterns.”
Forgiveness with LASIK
In LASIK when only one cut is made with that laser, there is a lot of forgiveness for those imperfections because afterwards, the flap is lifted and the ablation is done on the bed. When the flap is replaced back down, those imperfections still line up as long as you align the flap back in its original position because there is only one interface, Dr. Wilson explained.
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