Prospective, Randomized, Contralateral Eye Comparison of the Lenticule Decentration Following SMILE: Coaxially...

To examine lenticule decentration and visual quality following small incision lenticule extraction (SMILE) using either the coaxially sighted corneal light reflex (CSCLR) or the tear film mark (TFM) centration method.

A total of 186 eyes from 93 patients were enrolled in this prospective, randomized, contralateral eye comparison study. Each patient had one eye randomly assigned to the CSCLR group (n = 93) and the contralateral eye to the TFM group (n = 93). Visual outcomes, optical zone decentration, contrast sensitivity, corneal higher order aberrations (HOAs), and the relationships between the magnitude of decentration and induced corneal HOAs were evaluated at 3 months postoperatively.

The magnitudes of total decentration (CSCLR: 0.23 ± 0.13; TFM: 0.22 ± 0.13; P = .996), as well as horizontal and vertical decentration, were comparable between the two methods. However, in the angle kappa greater than 200 µm subgroup, a statistically significant smaller horizontal decentered displacement was observed in the CSCLR group (0.01 ± 0.16) compared to the TFM group (0.07 ± 0.18) (P = .024). The induced HOAs and contrast sensitivity were comparable between the two methods (all P > .05). Additionally, significant correlations were identified between total decentered displacement and induced HOAs, including RMS HOAs, RMS coma, vertical coma, and RMS spherical aberration, in both groups.

Both the CSCLR and TFM methods can yield accurate treatment centration and satisfactory visual quality. However, the CSCLR method may contribute to less horizontal decentration in patients with a large preoperative pupil offset. [.