Rotational stability and visual outcomes of V4c toric phakic intraocular lenses

PURPOSE: To investigate the clinical outcomes and rotational stability following implantation of V4c toric implantable collamer lenses (ICLs) (STAAR Surgical Company, Monrovia, CA) and to analyze the factors that influence rotational stability. METHODS: In this prospective observational case series, the authors analyzed the visual outcomes and rotational stability in 52 eyes of 52 patients immediately and 3 and 6 months after implantation. Postoperative rotation was defined as the angle between the adjusted axis and alignment axis. Central vaulting of the ICL was measured in a non-accommodative state using Visante optical coherence tomography (Carl Zeiss Meditec, Jena, Germany). Vector analysis of refractive astigmatism was performed. Regression analysis was used to investigate the association between the degree of rotation 6 months postoperatively and the associated variables. RESULTS: The mean efficacy index and safety index 6 months postoperatively were 1.35 ± 0.19 and 1.38 ± 0.22, respectively. In vector analysis, the magnitude of error was -0.20 diopters (D), indicating slight undercorrection. Absolute degree of rotation was 2.81° ± 1.87° immediately after the operation and 3.75° ± 2.92° and 3.87° ± 3.07° at 3 and 6 months postoperatively, respectively (P = .009). Bonferroni-adjusted post-hoc comparison showed that the absolute degree of rotation immediately after the operation was significantly smaller than that after 3 (P = .043) and 6 (P = .023) months, with barely any change after 3 months. No explanatory variable relevant to the absolute degree of rotation was discovered. CONCLUSIONS: The V4c toric ICL is predictable, safe, and effective in correcting low and high levels of astigmatism, showing relatively good postoperative rotational stability.