[Small Incision Lenticule Extraction (SMILE) for correction of myopic astigmatism]

To study the efficacy, stability, safety and predictability of small incision lenticule extraction (SMILE) at 1 day and 3 months postoperatively for moderate and high myopic astigmatism. To describe a simple and convenient method for detection and manual compensation of cyclotorsion during the procedure.

In this retrospective study, a total of 164 eyes from 114 patients over 20 years of age with at least 1.5 diopters (D) of myopic astigmatism were treated by SMILE. Any cyclotorsion was manually compensated by gently rotating the cone to align the horizontal marks on the cornea to the 0° to 180° axis of the reticule after activating the suction.

The mean preoperative spherical equivalent (SE) was -5.3±2.01 D, and the mean cylinder was -2.01±0.67 D. Three months after surgery, a total of 87% of eyes were within±0.50 D of attempted post-operative SE, and 98% of eyes were within±1.00 D. Overall, the predictability of cylinder correction was excellent, with 96.3% of eyes within±1.00 D of attempted post-operative cylinder. The mean postoperative cylinder at three months was -0.3±0.39 D. We noted a slight undercorrection with treatment of high cylinder. However, 82% of eyes achieved postoperative refractive astigmatism less than 0.5 D. 91% of eyes achieved uncorrected distance visual acuity (UDVA) equal to or better than 8/10. 22% of eyes gained one line of visual acuity.

SMILE is a predictable and safe technique for the surgical correction of astigmatism. Manual compensation may be an effective approach to improve astigmatic outcomes of SMILE, especially in moderate and high astigmatism.