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°, 45°, 90°, 135°) 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° (range: 0°-5°). 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° could be detected 6 months after surgery.