Rotational Stability and Clinical Effects of Different Toric ICL Placements: A Case- Control Study

Abstract Background To compare the visual and refractive outcomes, vault, and rotational stability between horizontal and vertical toric implantable collamer lens (ICL) placement. Methods This retrospective case-control study comprised 36 eyes of 36 patients with vertical toric ICL placement and 36 eyes of 36 patients with horizontal placement. The two groups were matched strictly 1:1 from January 2020 to October 2020. The visual acuity, vault, manifest refraction, efficacy index (EI), safety index (SI), vector analysis, and rotational stability were compared between the two groups. Results Residual astigmatism in the vertical group was slightly smaller than that in the horizontal group (P = 0.024), and the index of success (IOS) was slightly greater in the vertical group than in the horizontal group (P = 0.013). Furthermore, the vault was significantly higher in the horizontal placement group than in the vertical placement group (P < 0.001). Compared to the preoperative design, the absolute degree of rotation at 3 months postoperatively was 3.44° ± 2.72° for the horizontal group and 4.83° ± 2.93° for the vertical group. However, if the reference was changed to 2 hours postoperatively, the absolute rotation degree was 1.81° ± 1.84° for the horizontal placement group and 1.97° ± 1.70° for the vertical placement group. There was no significant difference in other parameters between the two groups. Conclusions Vertical placement of a toric ICL can have clinical effects and rotational stability as good as those with horizontal placement. Moreover, compared with horizontal placement, vertical placement can effectively reduce vault.