AIM: To evaluate the influence of slight eye movement during laser scanning on femtosecond laser precision of corneal ablation and postoperative refractive status in small incision lenticule extraction(SMILE).

METHODS: Totally 32 patients(62 eyes)who underwent SMILE surgery in our hospital from January 2019 to March 2021 were included and divided into the movement group and the fixation group according to whether the eyeballs were slightly moved during the operation, and select patients with slightly moved monocular eyeballs for binocular pairing. The actual difference of absolute value of corneal absolute cutting error(ACE), astigmatism error(AE), absolute refractive error(ARE)and absolute visual error(AVE)was compared between the movement group and the fixation group and the two eyes of the patients with slight ocular movement in one eye at 1mo after surgery, and the surgical images were quantified to analyze the correlation between the amplitude of ocular movement and AE, and to compare the effects of the area, layer and direction of slight eye movement on ACE.

RESULTS: There were no differences in all observed results between movement group and fixation group(P>0.05). Patients with slight movement of one eye had a difference in binocular AE(0.57±0.31D vs 0.33±0.27D, P<0.05), and the amplitude of movement was positively correlated with AE at 1mo after surgery(r=0.564, P<0.05). There was no statistical differences in ACE at 1mo after surgery in patients with slight ocular movement in different regions(central/peripheral), layers(upper/lower lens)and direction(nasal/temporal)(all P>0.05).

CONCLUSION:The slight eye movement during laser scanning in SMILE has no significant influence on precision of corneal ablation. It mainly causes decentered ablation and the changes of corneal astigmatism, which has little effect on the spherical equivalent and visual acuity.