Evaluation of the long-term rotational stability of single-piece, acrylic intraocular lenses

Objectives To assess rotational stability beyond 3 months and compare the different designs and materials of two acrylic intraocular lenses (Akreos Adapt (Bausch & Lomb, Rochester, New York, USA) and AcrySof SA60AT (Alcon, Fort Worth, Texas, USA)). Methods Post hoc analysis of retro-illumination images from a previous multicentre, contralateral eye study was used to assess intraocular lens (IOL) position and rotational stability for up to 24 months postoperatively. The image of IOL and capsular bag enabled any rotation to be calculated by measuring the angle from the horizontal to an arbitrary point on the IOL edge. The difference between the angle at the first and subsequent visits was subtracted to give a measure of IOL rotational stability. Results Data were collected from 64 eyes fitted with the Akreos IOL and 58 eyes fitted with the AcrySof IOL. Mean (SD) absolute rotation values for the two IOLs were small over the 2-year period, ranging from 2.53 degrees (2.40 degrees) to 3.2 degrees (2.57 degrees) with Akreos Adapt and 2.67 degrees (2.22 degrees) to 3.33 degrees (3.06 degrees) with AcrySof SA60AT at 6 and 24 months, respectively. The differences were not statistically significant. Using the ANSI draft toric IOL standard, the percentage of lenses rotating <= 5 degrees was 90% at 6 months, 91% at 12 months and 80% at 24 months for the Akreos lens and 89% at 6 months, 75% at 12 months and 81% at 24 months for the AcrySof lens. Conclusion Spherical, single-vision acrylic IOLs continue to show some tendency to rotate for up to 24 months postoperatively, although this is usually small. The Akreos Adapt lens may be a good platform for a toric lens product.