Multizonal Design Multifocal Intraocular Lens–Induced Astigmatism According to Orientation

Abstract

PURPOSE: To evaluate the differences in intraocular lens (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. [ J Refract Surg . 2020;36(11):740–748.]

Spectral Effects and Range of Focus in a Multizonal-Refractive Intraocular Lens Compared with a Standard Trifocal Diffractive Design

“…Although zero-defocus VA was better than predicted from our optical measurements in those clinical studies, at − 1 D, the MTF-based prediction appears to overestimate VA. In our study, a VA value of 0.05 logMAR was predicted, but for Eom et al, it was 0.1 logMAR [ 28 ]. We noted a similar difference in the prediction for PanOptix, which, besides clinical factors, may also indicate the need for refinement of the applied VA-prediction formula.…”

“…Eom et al enrolled 40 patients implanted with the Precizon and assessed IOL-induced astigmatism [ 28 ]. That study found an increase in astigmatism related to the IOL ranging from 0.68 ± 0.58 D to 1.05 ± 0.81 D, depending on the lens orientation.…”

“…Still, this finding may support our observation of the astigmatic-like effect in the recorded USAF-target images. Secondary to the astigmatism assessment, Eom et al reported a binocular defocus curve for their patients [ 28 ]. Alió et al also evaluated the defocus curve of ten (Precizon 570 NVA) patients [ 29 ].…”

A comparison of clinical outcomes and optical performance between monofocal and new monofocal with enhanced intermediate function intraocular lenses: a case-control study

“…After that the lenses center and the camera were precisely aligned so that the image focus was on the camera’s sensor. The 1951 USAF resolution chart was illuminated by 555 nm LED light, and the image formed by the model eye was obtained by the CMOS camera [ 14 , 15 ]. The trial lens was placed in front of the model eye to obtain defocus image between − 2.50 D and + 1.00 D in 0.50 D intervals [ 16 ].…”

“…The images were converted to through-focus modulation transfer function (MTF) in the horizontal and vertical directions using the MatLab (Mathworks, Inc., Natick, MA) [ 17 ]. The root mean square of the horizontal and vertical MTF (MTF RMS ) was calculated using the following formula [ 15 ]: …”