Efficacy Comparison Between Steep-Meridian Incision and Non-Steep-Meridian Incision in Implantable Collamer Lens Surgery with Low-to-Moderate Astigmatism

INTRODUCTION: To compare the visual outcomes of astigmatism correction with implantable collamer lens (ICL) surgery with low-to-moderate astigmatism through a steep-meridian corneal relaxing incision (SM–CRI) and non-steep-meridian corneal relaxing incision (NSM–CRI). METHODS: Seventy eyes of 70 patients with myopia and myopic astigmatism who underwent ICL V4c implantation were classified into two groups: SM–CRI and NSM–CRI. Refractive outcomes and vector analysis were evaluated preoperatively and 6 months postoperatively. RESULTS: At the postoperative 6 month visit, all participants in both groups achieved an uncorrected distance visual acuity (UDVA) of 20/20 or better. The difference vector (DV) showed that the residual astigmatism in the SM–CRI group was much smaller than that in the NSM–CRI group (P = 0.021), and the correction index (CI) was 0.84 ± 0.30 and 0.67 ± 0.35 for the SM–CRI and NSM–CRI groups, respectively, with a significant statistical difference (P = 0.013). Approximately 71% of eyes in the SM–CRI group had an angle of error (AE) within ± 15°, whereas 55% of eyes in the NSM–CRI group were within that range. The absolute mean AE was 10.13 ± 14.57° in the SM–CRI group, compared with 23.88 ± 28.22° in the NSM-CRI group (P = 0.038). CONCLUSION: SM–CRI can alleviate corneal astigmatism and decrease the cylindrical diopter of the ICL, thus improving postoperative visual quality compared with NSM–CRI.