The Impact of Horizontal Marking on the VisuMax Surgical Bed Headrest on the Outcomes of Myopic Astigmatism Correction With Small Incision Lenticule Extraction.

Abstract

Aims: To investigate the impact of horizontal markings on the VisuMax surgical bed headrest on the accuracy of astigmatism correction in small incision lenticule extraction (SMILE). Methods: This retrospective study categorized preoperative astigmatism severity into low-astigmatism (-0.25 to -1.75 D) and moderate-to-high astigmatism (-2.00 to -4.50 D). A preoperative patient fixation training regimen coupled with applying horizontal markings on the VisuMax surgical bed headrest was introduced to improve the precision of astigmatism correction. The effectiveness of SMILE was compared to femtosecond laser-assisted in situ keratomileusis (FS-LASIK) in correcting astigmatism by using Alpins vector analysis, as well as the higher-order aberrations were measured. Results: This study included 170 patients (56 eyes in the low-astigmatism group and 31 eyes in the moderate-to-high astigmatism group of SMILE; 47 eyes in the low-astigmatism group and 36 eyes in the moderate-to-high astigmatism group of FS-LASIK). At 6 months postoperatively, safety and efficacy indices between SMILE and FS-LASIK showed no significant differences for either astigmatism group (p > 0.05). However, significant differences were observed in surgically induced astigmatism (SIA), magnitude of error (ME), and correction index (CI). A considerable difference in equivalent spherical (SE) was found in the low-astigmatism group (p < 0.05). No significant differences were noted in the angle of error (AE) and its absolute value (|AE|) between the two procedures (p > 0.05). Both techniques increased total higher-order aberrations, spherical aberration, and vertical coma, with SMILE associated with a significantly higher increase in vertical coma than FS-LASIK (p < 0.05). Conclusions: Augmented by precise preoperative strategies, including headrest marking and fixation training, SMILE achieves astigmatism axis correction efficacy comparable to FS-LASIK. SMILE and FS-LASIK are effective and comparable in correcting moderate-to-high astigmatism, highlighting their safety, efficacy, and predictability as corrective measures for myopic astigmatism.