SMILE laser eye surgery is a relatively new technique of vision correction. LASIK surgery involves creating a flap in the cornea which is then lifted with correction of the surface underneath. The flap is then returned into position. In SMILE a single laser creates a lens of tissue within the cornea which is freed up by the surgeon and then removed through a small surface incision. The purported benefits of SMILE relate to the absence of a flap and are claimed to be less incidence of dry eye after surgery and a stronger cornea due to the absence of a flap. SMILE has been marketed as more advanced and better than LASIK and other procedures. Convincing evidence for these claims having been lacking. Corneal ectasia or keratoconus arising after laser eye surgery is rare and thought to arise from biomechanical changes in the cornea after LASIK. Uptil now, clinics performing SMILE have claimed that SMILE is biomechanically safer and some surgeons have pushed the accepted maxima of laser eye correction based on this assumption.
A recent editorial and published evidence now show that corneal ectasia or keratoconus can occur after SMILE and that this procedure is no safer than LASIK. Clinics promoting SMILE on the pretext of less dry eye and stronger corneas may be misleading patients in view of current evidence. Current guidance suggests that surgeons performing SMILE should carry out the same stringent pre-operative tests that LASIK patients have and that they should not attempt to treat levels of myopia that they would otherwise not attempt with LASIK. Read the editorial here.
In our own experience of SMILE at Moorfields Eye Hospital, we found our results to be the same as LASIK, but with variable rates of visual recovery after SMILE compared to LASIK. As we were trialling this technique, we only treated patients who we would have otherwise performed LASIK on and did not treat higher than normal corrections. None of our patients lost any lines of vision. We are no longer performing SMILE surgery as we did not feel that it was any better than our current treatments - LASIK, LASEK, TransPRK.