Profile of oxidative stress in tears of patients undergoing laser in situ keratomileusis (LASIK) and small incision lenticle extraction (SMILE)

Abstract

Purpose : To measure the profile of oxidative stress present in tears of patients undergoing refractive surgery with the LASIK and SMILE techniques.

Methods : Prospective, observational and descriptive. Patients older than 21 years with maximum spherical refractive error of -7.50 D and maximum with the rule astigmatic error of -3.25 D were included for SMILE. Patients with -7.25 D maximum for myopic refractive error, and -5.75 D of with the rule astigmatism were included for LASIK. The activity of superoxide dismutase, glutathione peroxidase, malondialdehyde and catalase was sought by an enzyme-linked immunosorbent assay (ELISA) in tear samples that were taken before surgery, at the end of it and 7 days postoperatively, correlating the changes in the oxidative profile of the eye surface with the parameters used in each surgery.

Results : Tear samples from 71 eyes were analyzed, of which 52.11% (37 eyes) were operated with LASIK and 47.88% (34 eyes) were operated with SMILE. The age range was from 21 to 40 years, with the average being 27.15. 83.09% (59 eyes) were from female patients and 16.9% (12 eyes) were from male patients.
A lower amount of superoxide dismutase, catalase and glutathione peroxidase was obtained 7 days after surgery compared to the baseline state and the immediate postoperative state in patients operated with LASIK and SMILE (p<0.05). On the other hand, the amount of malondialdehyde was higher 7 days after surgery compared to the baseline state and the immediate postoperative state in both groups (p<0.05). No difference was found in the oxidative stress profile between the 2 types of refractive surgery in the immediate postoperative period or 7 days after surgery.

Conclusions : Patients operated with LASIK and SMILE suffer from an imbalance in the REDOX state of the ocular surface due to a decrease in antioxidant enzymes and an increase in peroxidation products with no difference between the two types of refractive surgery.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.