Comparing Rotational Stability Over Time Between Four Monofocal Toric Intraocular Lenses.

Purpose: To evaluate the rotational stability of four different monofocal toric intraocular lenses (IOLs) from surgery to 4-6 months postoperative.

Methods: This was a subset of data from a prospective multi-center randomized clinical study. High resolution retro-illuminated images of eyes implanted with four different toric IOLs were obtained immediately after surgery, and at 1 day, 1 week, 1 month and 4-6 months after surgery. Fixed scleral features were identified in the surgical image. An independent reading center evaluated the orientation of the IOL from all images, based on the angle between the toric axis marks and these fixed scleral landmarks. Rotational stability was determined by calculating differences in orientation between visits.

Results: Digital images from 299 eyes implanted with one of the four IOLs were available for analysis. Orientation data were successfully determined in about 90% of images. Biometry and IOL orientation were not significantly associated with IOL rotation. The Vivinex lens showed the lowest absolute rotation, with a mean value less than 1.5 degrees at all time intervals measured, with a maximum standard deviation of 1.4 degrees. The AcrySof lens was next lowest, with an absolute rotation below two degrees for all intervals. Mean absolute rotation for the Tecnis lens was significantly higher than for the other IOLs (>2 degrees for all intervals). For the AcrySof and Vivinex lenses, there were no reported rotations >10 degrees for any interval; 97% or more of results were <5 degrees, compared to 93% for the AT Torbi lens and 90% for the Tecnis lens. Only 6 lenses (4 Tecnis: 8.3%, 2 AT Torbi: 4.3%) had a rotation > 10 degrees at any time point.

Conclusion: Rotational stability appeared excellent for the Vivinex and AcrySof toric IOLs, with slightly more variable performance evident with the AT Torbi and Tecnis IOLs.