Corneal Sensitivity, But Not Patient-Reported Dry Eye Symptoms, Differs Following LASIK and SMILE

Laser Eye Surgery
Although LASIK was linked with greater corneal denervation than SMILE, patients did not experience different symptoms.

Laser-assisted in situ keratomileusis (LASIK) causes greater corneal denervation than small incision lenticule extraction (SMILE) in the early postoperative period, according to the results of a study published in the American Journal of Ophthalmology. However, researchers report no significant differences in self-reported dry eye symptoms between the groups.

Investigators with the Byers Eye Institute, Stanford University, Palo Alto, California, conducted a prospective randomized contralateral-eye clinical trial to compare corneal sensation and patient-reported symptoms of dry eye in patients undergoing LASIK and SMILE ( Identifier: NCT03067077).

The team evaluated 80 eyes of 40 patients (mean age, 34 years; range, 24-54 years) with myopia who were randomized to receive wavefront-guided femtosecond LASIK in an eye and SMILE in the fellow eye. They assessed corneal sensitivity preoperatively and at the 1-month, 3-month, 6-month, and 12-month postoperative visits. At each visit, the participants completed questionnaires to determine the Ocular Surface Disease Index (OSDI).

The researchers demonstrated that eyes that underwent LASIK had more cornea denervation on average than those that underwent SMILE at the postoperative 1-month (2.1 vs 3.6 cm; P <.001), 3-month (3.5 vs 5.4 cm; P <.001) and 6-month (4.7 vs 5.7 cm; P <.001) visits. At the 12-month visit, they found that both groups had returned to the baseline corneal sensitivity (5.9 vs 5.9 cm, P =.908). 

The team observed no difference in OSDI between the groups at any visit. From the preoperative visit to the postoperative 12-month visit, they found that the mean OSDI improved in both the LASIK (15.3 to 8.6; P =.020) and SMILE (15.1 to 9.5; P =.029) groups.

“LASIK resulted in greater corneal denervation compared to SMILE in the early postoperative period, though this difference was no longer apparent after 12 months,” according to the research team. “Despite this, there was no difference in self-reported dry eye symptoms between the two groups. Patient-reported dry eye symptoms improved after both LASIK and SMILE procedures.”

Disclosure: This research was supported by Johnson & Johnson Vision. One study author declared affiliations with the biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Ma KK, Manche EE. Corneal sensitivity and patient-reported dry eye symptoms in a prospective randomized contralateral-eye trial comparing LASIK and SMILE Am J Ophthalmol. Published online, May 17, 2022. doi:10.1016/j.ajo.2022.05.010