Evaluation of the True Wavefront Aberrations in Eyes Implanted With a Rotationally Asymmetric Multifocal Intraocular Lens

Abstract

ataract is successfully treated by replacement of the crystalline lens with an intraocular lens (IOL). Monofocal IOLs are preferably set for far vision and reading glasses are used for near vision. The dependency on glasses after cataract surgery can be eliminated with the help of multifocal IOLs that provide multiple foci and thereby enable functional simultaneous vision at far, intermediate, and near distances. Most designs of multifocal IOLs are diffractive, refractive, or hybrid. 1A rotationally asymmetric refractive multifocal IOL design has gained popularity in the past decade. This design provides two distinct foci with its two definite correcting zones for far and near vision. In general, there is a smooth transition between the two zones. The Lentis Mplus IOL (Oculentis GmbH, Berlin, Germany) is based on this design and has demonstrated good near and distance visual outcomes and good contrast sensitivity.2 The presence of a large magnitude intraocular primary coma has been reported in patients implanted with this multifocal IOL, which is usually attributed to its vertical asymmetric optical geometry. 3,4 In addition, it is believed that the presence of this optical defect allows an extended depth of focus that would grant adequate vision at various distances. On the other hand, it is assumed that this additional coma causes C ABSTRACT PURPOSE: Standard evaluation of aberrations from wavefront slope measurements in patients implanted with a rotationally asymmetric multifocal intraocular lens (IOL), the Lentis Mplus (Oculentis GmbH, Berlin, Germany), results in large magnitude primary vertical coma, which is attributed to the intrinsic IOL design. The new proposed method analyzes aberrometry data, allowing disentangling the IOL power pupillary distribution from the true higher order aberrations of the eye. METHODS:The new method of wavefront reconstruction uses retinal spots obtained at both the near and far foci. The method was tested using ray tracing optical simulations in a computer eye model virtually implanted with the Lentis Mplus IOL, with a generic cornea or with anterior segment geometry obtained from custom quantitative spectral-domain optical coherence tomography in a real patient. The method was applied to laser ray tracing aberrometry data at near and far fixation obtained in a patient implanted with the Lentis Mplus IOL. RESULTS:Higher order aberrations evaluated from simulated and real retinal spot diagrams following the new reconstruction approach matched the nominal aberrations (approximately 98%). Previously reported primary vertical coma in patients implanted with this IOL lost significance with the application of the proposed reconstruction.CONCLUSIONS: Custom analysis of ray tracing-based retinal spot diagrams allowed decoupling of the true higher order aberrations of the patient's eye from the power pupillary distribution of a rotationally asymmetric multifocal IOL, therefore providing the appropriate phase map to accurately evaluate through-focus optical quality.[J Refract Surg. 20...

Comparative Analysis of Visual Performance and Optical Quality with a Rotationally Asymmetric Multifocal Intraocular Lens and an Apodized Diffractive Multifocal Intraocular Lens

“…It should be considered that the introduction of coma does not always have a positive effect on the depth of foci. e introduction of the positive amounts of coma or trefoil causes inverse problems and limits vision outcomes in some cases, which were previously due to the imbalance between the blur induced by aberrations and the visual benefit from it [29]. Furthermore, the tilt and decenter of rotationally asymmetric MIOL also caused a larger amount of high-order aberrations.…”

Bifocal and Multifocal Contact Lenses for Presbyopia and Myopia Control

“…Most clinical studies with multifocal contact lenses are limited to reports of through-focus visual acuity and contrast sensitivity, generally aiming at a depth of focus analysis and the improvement in near vision without compromising distance visual acuity. Aberrometry is an important clinical tool for objective evaluation of the image quality and visual performance prediction; however, due to the coupling of the phase of concentric multifocal designs there are some technical difficulties in the wavefront reconstruction of current sensors (true ocular aberrations and the power distribution in the pupil area), requiring an accurate reconstruction method for a proper combination of the wavefront slopes estimated at far and near distances [49]. Recently, theoretical visual simulations in eye models with multifocal designs and experimental visual simulators have shown the theoretical and real visual performance of different lens designs.…”

Experimental validations of a tunable-lens-based visual demonstrator of multifocal corrections

“…The multifocal phase maps are evaluated in a pseudophakic computer eye model [16] and the corresponding TF VS ratios are obtained using the following expression [18]:…”

“…The calculation uses the through-focus (TF) Visual Strehl (VS) ratio of a given multifocal phase map. In the case of M-IOLs, the multifocal phase maps can be extracted in a pseudophakic computer eye model [16] from the knowledge of the surface profile of the lenses. Alternately, the multifocal phase maps corresponding to the contact lenses can be evaluated from the optical power profiles [17].…”