2 AbstractPurpose: To evaluate the incidence of central hole-induced ring-shaped dysphotopsia after posterior chamber phakic implantable collamer lens (ICL) with central hole (hole ICL) implantation and to investigate the causes of central hole-induced dysphotopsia. Methods:The clinical study enrolled 29 eyes of 15 consecutive myopic patients implanted with hole ICL. The incidence of ring-shaped dysphotopsia after hole ICL implantation was evaluated. In the experimental simulation study, non-sequential ray tracing was used to construct myopic human eye models with hole ICL and ICL without a central hole (conventional ICL). Simulated retinal images measured in log-scale irradiance were compared between the two ICLs for an extended Lambertian light-emitting disk object 20 cm in diameter placed 2 m from the corneal vertex. To investigate the causes of hole-induced dysphotopsia, a series of retinal images were simulated using point sources at infinity with well-defined field angles (0 to -20º) and multiple ICL models.Results: Of 29 eyes, 15 experienced ring-shaped dysphotopsia after hole ICL implantation. The simulation study using an extended Lambertian source showed that hole ICL-evoked ring-shaped dysphotopsia was formed at a retinal field angle of ± 40º. Component level analysis using a welldefined off-axis point source from infinity revealed that ring-shaped dysphotopsia was generated by stray light refraction from the inner wall of the hole and the posterior ICL surface. Conclusion:Hole ICL-evoked ring-shaped dysphotopsia was related to light refraction at the central hole structure. Surgeons are advised to explain to patients the possibility of ring-shaped dysphotopsia after hole ICL implantation.

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.]

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