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Intraocular lens (IOL) technology is expanding considerably, creating a wide array of lens types. More studies are examining how optic aberrations resulting from IOLs affect the image quality projected onto the retina. For instance, higher resolution far-distance images are best for neuroadaptation, thus, better vision.
A study published in Eye and Vision compares postimplantation retinal image quality of 9 premium IOLs by examining point spread function (PSF) Strehl ratio using a new pyramidal wavefront sensor (PWS) aberrometer, Osiris® (Costruzione Strumenti Oftalmici, CSO). Lenses assessed include monofocal spherical and aspheric, extended depth of focus (EDoF), multifocal refractive and diffractive, and accommodative designs.
Far-distance retinal image quality significantly differed between the IOLs implanted in 194 eyes of 120 patients with cataract, mean age 63.5±9.7 years, during the 3-month prospective case series conducted by investigators in Italy and Spain. Because monofocal lens design focuses all light on axis to the retinal plane, the control group patients receiving Acrysof® SA60AT (Alcon AG) obtained optimal postoperative image quality; a mean PSF without second-order aberrations (PSFw2) Strehl ratio of 0.28±0.07 at a pupil diameter of 4.0 mm.
Two trifocals provided high retinal image quality: the AT LISA® Tri 839MP (Carl Zeiss Meditec) with PSFw2 Strehl ratio of 0.31±0.10 for 4.0 mm pupil; and PanOptix Trifocal (Alcon AG) at 0.26±0.04 for 4.0 mm pupil. Two IOLs did not match the PSFw2 Strehl ratio of monofocals, but showed good results: the accommodative IOL AkkoLens Lumina® (AkkoLens Clinical BV) offered 0.23 ±0.16, and new aspheric monofocal TECNIS EyhanceTM (Johnson & Johnson Vision Care, Inc.) reached 0.21±0.06, both for 4.0 mm pupil.
A larger add in a rotationally asymmetric lens may limit optical quality, affecting the far-distance image, according to the study. Thus, the multifocal refractive lens Lentis® Mplus LS-313 MF30, “with a 3.00 D posterior sector-shaped near-vision zone” yielded a PSFw2 Strehl ratio of 0.18±0.06 at 4.0 mm pupil, compared with Lentis Mplus LS-313 MF15 showing a higher ratio of 0.21±0.06 at 4 mm pupil diameter.
Precizon® Presbyopic (Ophtec BV), a continuous transitional focus IOL, produced less retinal definition; 0.17±0.04 for 4.0 mm pupil. The EDOF Sifi Mini Well® (SIFI MedTech) delivered a ratio of 0.21±0.06 for 4.0 mm pupil, but had a 31.6% substitution rate (P =.002), possibly due to neuroadaptation difficulties. The investigation speculates that since this type of lens increases depth of focus using spherical aberration, retinal image quality may be reduced.
Limitations of the analysis include the possibility of residual ametropia having an influence on results, and the ability of Osiris to “simulate the main PSF of a diffractive lens,” which may have caused a similar or higher PSFw2 compared with monofocals. This research is first to evaluate postoperative optics using a new PWS-based aberrometer. “Learning how the different IOL optics influence the quality of retinal image by the study of induced aberrations with the novel PWS-based aberrometer, may be considered as a new clinical tool for IOL selection,” according to the investigation.
Reference
Alio JL, D’Oria F, Toto F, et al. Retinal image quality with multifocal, EDoF, and accommodative intraocular lenses as studied by pyramidal aberrometry. Eye and Vis. 2021;8(37):1–11. doi:10.1186/s40662-021-00258-y
