Effect of Cyclotorsion Compensation With a Novel Technique in Small Incision Lenticule Extraction Surgery for the Correction of Myopic Astigmatism.

Abstract

To comparatively investigate the clinical outcomes of small incision lenticule extraction (SMILE) surgery with or without cyclotorsion compensation for the correction of myopic astigmatism. This prospective, double-blinded, randomized controlled trial included patients who underwent SMILE surgery with bilateral myopic astigmatism. Two eyes of a single patient were randomly divided into the static cyclotorsion compensation (SCC) group and the control group. In the SCC group, the intraoperative cyclotorsion was manually compensated with a novel technique. In the control group, the cyclotorsion was not compensated. Visual acuity, manifest refraction, aberrations, objective visual quality, and contrast sensitivity were measured preoperatively and postoperatively. A total of 132 eyes from 66 patients were analyzed at the 3-month follow-up. The mean preoperative cylinder values in the SCC and control groups were -1.52 ± 0.81 and -1.57 ± 0.82 diopters (D), respectively. The mean cyclotorsion during surgery was 0.60° ± 0.63° (range: 0° to 3.2°) in the SCC group and 3.21° ± 2.33° (range: 0.1° to 10.8°) in the control group (P < .001). Both groups showed favorable results in the correction of myopic astigmatism. No statistically significant difference was found between the two groups in visual and refractive outcomes, vector parameters, entire eye aberrations, objective visual quality, or contrast sensitivity. No significant benefit was gained from cyclotorsion compensation, even in the high astigmatism subgroup. The cyclotorsion compensation technique used in this study helped minimize the alignment error but was not compulsory because the ocular rotation in SMILE surgery using a well-controlled position was too small to affect the astigmatic outcomes or postoperative visual quality. [J Refract Surg. 2019;35(5):301-308.].