LASIK vs SMILE: Differences in Corneal Sensitivity, Dry Eye

The eyes of patients undergoing laser-assisted in situ keratomileusis (LASIK) surgery have reduced corneal sensitivity in the first 6 months postoperatively compared with patients undergoing small-incision lenticule extraction (SMILE), a randomized trial showed.

However, no differences persisted at 12 months, nor were there changes in dry eye symptoms reported across the duration of the study, which was presented at the American Academy of Ophthalmology (AAO) meeting.

In this exclusive MedPage Today video, Edward Manche, MD, professor of ophthalmology at Stanford University School of Medicine in California, discusses the results.

Following is a transcript of his remarks:

Basically, I conducted a prospective randomized contralateral fellow-eye study randomizing patients to receive wavefront-guided LASIK in one eye and SMILE surgery in the fellow eye. And we looked at a number of outcome measures, and some of it had already been published, the results section. But at the Academy we presented results on corneal sensitivity and self-reported dry eye findings in this cohort of patients.

It was interesting what we found. So we measured corneal sensation with Cochet-Bonnet esthesiometry, and we measured patients preoperatively at post-op months 1, 3, 6, and 12. We also administered a self-reported questionnaire to the patients, and that contained the Ocular Surface Disease Index (OSDI). And we also administered that questionnaire preoperatively at post-op months 1, 3, 6, and 12.

And it was interesting what we found. What we expected to find and did find was a reduction in corneal sensitivity in both groups. It was more profound in the LASIK group compared to the SMILE group in the early postoperative period. So there’s a fairly profound decrease in corneal sensation with LASIK. There is also a reduction with SMILE, but it’s not as profound as we see with LASIK. And this difference between LASIK and SMILE was present at post-op months 1, 3, and 6. By 12 months, both groups had completely recovered back to baseline. The SMILE group was pretty much back to normal by 6 months. And this has been shown before in the literature.

However, what was really interesting to us was that when we looked at the OSDI index results, the self-reported dry eye results, patients could not perceive any difference in self-reported dry eye at any time interval between LASIK and SMILE. And that was a bit surprising. So despite this difference in corneal sensitivity, there was no difference in self-reported dry eye symptoms.

One of the other interesting things was that if you looked at the subcategories — mild, moderate, severe — in the [OSDI], preoperatively about 10% of eyes are patient reported severe OSDI scores. And then if you looked at post-op month 12, the subgroup, there was no patients in either SMILE or LASIK that had rated their dry eye symptoms as severe. And even more interestingly, if you looked at the preoperative values of OSDI, they had been reduced to about half at post-op month 12. So not only was there no worsening, there was actually improvement in both groups. So I think that’s really encouraging.