True rotational stability of a single-piece hydrophobic intraocular lens

Background To evaluate rotation and its influencing factors of an aspheric one-piece hydrophobic acrylic intraocular lens (IOL) Vivinex XY1 during 6 months after operation. Methods In this institutional trial, 122 eyes of 66 patients were implanted with a non-toric aspheric IOL Vivinex XY1 (Hoya Corporation, Tokyo, Japan). IOL alignment was assessed at the end of surgery, 1 hour, 1 week, 1 month and 6 months after implantation. Confounding factors such as axial length, presence of anterior fibrosis and randomised implantation in four different intended axes (0 degrees, 45 degrees, 90 degrees, 135 degrees) were evaluated. Decentration and tilt were measured using a Purkinje metre. Results Assessment of rotational stability was possible for 103 of 122 implanted IOLs 6 months after eye surgery. The median absolute rotation was 1.1 degrees (range: 0 degrees-5 degrees). Rotation was significantly increased within the first hour after operation compared with later time-points (p<0.001). No correlation was found with axial length and rotation (Spearman's r=0.048, p=0.63). No significant difference was observed regarding different implantation axes (p=0.75). Rotation was not influenced by the presence of anterior fibrosis (p=0.98). Conclusion Assessing the true IOL position at the end of surgery is crucial for the evaluation of rotational stability of IOLs. No IOL rotation exceeding 5 degrees could be detected 6 months after surgery.