Multizonal Design Multifocal Intraocular Lens-Induced Astigmatism According to Orientation

PURPOSE: To evaluate the differences in intraocular tens (IOL)-induced astigmatism according to differences in orientation of a multizonal multifocal IOL, the Precizon Presbyopic NVA IOL (Ophtec BV). METHODS: The clinical study reviewed 80 eyes from 40 patients with cataracts who underwent Precizon Presbyopic IOL implantation. Residual astigmatism, as measured by autorefraction and manifest refraction, was investigated using vector analysis of eyes implanted with vertical (90 +/- 30 degrees) and horizontal (180 +/- 30 degrees) orientations of the first near segment of the IOL. In the ray-tracing simulation study, pseudophakic eyes with the Precizon Presbyopic IOL were modeled. The modulation transfer function (MTF) of each case was compared with respect to the amount of corneal astigmatism of the model eyes and the orientation of the first near segment. RESULTS: The mean IOL-induced astigmatism measured by autorefraction was 0.68 +/- 0.58 diopters (D) at 1 degree in the vertical orientation of the first near segment (n = 52) and 1.05 +/- 0.81 D at 96 degrees in the horizontal orientation (n = 28). However, the mean IOL-induced astigmatism measured by manifest refraction was 0.14 +/- 0.44 D at 171 degrees and 0.46 +/- 0.40 D at 95 degrees. The MTF analysis showed that the highest MTF values were measured in eyes without corneal. astigmatism in both the vertically and horizontally implanted IOLs. CONCLUSIONS: Autorefraction measurement indicates induction of with-the-rule astigmatism by the Precizon Presbyopic IOL when implanted vertically with respect to the first near segment, and against-the-rule astigmatism when implanted horizontally. However, this astigmatism is clinically insignificant according to manifest refraction and ray-tracing simulation.