Decentration of optical zone center and its impact on visual outcomes following SMILE.
OBJECTIVE
To evaluate decentration from pupil center and corneal vertex normal following femtosecond laser small incision lenticule extraction (SMILE) for the treatment of myopia and myopic astigmatism.


METHODS
This study evaluated 101 eyes of 101 patients with a spherical equivalent (SE) of -5.30 ± 1.72 diopters (D). Decentration was measured in the pupil-centered group (PC group) by video capture images and in the vertex normal-centered group (VNC group) using the WaveLight Oculyzer II (Alcon). The PC and VNC groups were further divided into 4 subgroups (1 PC, 2 PC and 1 VNC, 2 VNC) based on the displacement of the lenticule center. Uncorrected and corrected distance visual acuities, manifest refraction, and wavefront errors were measured preoperatively, and at 1 day, 1 week, 1 month, and 3 and 6 months postoperatively.


RESULTS
Regarding efficacy and safety, at 6 months postoperatively, 65, 71, 83, and 53% of eyes had unchanged corrected distance visual acuity in 1 PC, 1 VNC, 2 PC and 2 VNC groups, respectively. Also, 97, 98, 100, and 97% of treated eyes had a postoperative uncorrected distance visual acuity 20/20 or better in the subgroups, respectively. In the groups mentioned above, 96, 100, 100, and 95% of eyes, respectively, were within ±0.5 D of the targeted SE. In terms of total higher-order aberrations, the 1 PC group was significantly higher than the 1 VNC group (P = 0.04), whereas the 2 VNC group was significantly higher than the 2 PC group (P = 0.02).


CONCLUSIONS
Our results demonstrate that better refractive outcomes will be achieved when the lenticule center is closer to the corneal vertex normal.
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
Manli
M
Liu
Yuan
Y
Sun
Danyang
D
Wang
Ting
T
Zhang
Yugui
Y
Zhou
Hua
H
Zheng
Quan
Q
Liu
D000293:Adolescent; D000328:Adult; D001251:Astigmatism / Q000601:surgery*; D003319:Corneal Stroma / Q000601:surgery*; D048988:Corneal Surgery, Laser / Q000379:methods*; D057108:Corneal Wavefront Aberration / Q000503:physiopathology; D005260:Female; D006801:Humans; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D008297:Male; D009216:Myopia / Q000601:surgery*; D011446:Prospective Studies; D011680:Pupil / Q000502:physiology; D012029:Refraction, Ocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult