Topography and longitudinal chromatic aberration characterizations of refractive-diffractive multifocal intraocular lenses

Characterizing glare effects associated with diffractive optics in presbyopia-correcting intraocular lenses

PURPOSE

To objectively quantify glare of intraocular lenses (IOLs) using a diffractive principle to extend the visual range and to identify models with increased susceptibility to inducing glare.

SETTING

David J Apple Laboratory, Heidelberg, Germany.

DESIGN

Laboratory investigation.

METHODS

Glare was assessed by means of a straylight parameter with a standard C-Quant intended for 7 degrees. In addition, 2 C-Quant modifications were used to test lower angles (ie, 2.5 degrees and 3.5 degrees). The following IOL models were assessed: PanOptix, AT Lisa Tri, Synergy, and Triumf, the latter 2 with chromatic aberration correction at distance. Straylight from trifocal IOLs was compared against a monofocal W-60R lens. The C-Quant test was performed through the studied IOLs by using additional optical components attached to their ocular.

RESULTS

Straylight (deg 2 sr -1 ) of the control was <1 at all tested angles, with the trifocal models showing comparable straylight at 7 degrees. At 3.5 degrees, Triumf's straylight increased to 15.5 ± 0.6, followed by Synergy (6.2 ± 1.1), PanOptix (4.1 ± 0.3), and AT Lisa Tri (2.0 ± 0.8). The chromatic aberration-correcting models demonstrated correspondingly higher straylight (Synergy: 18.8 ± 1.3; Triumf: 17.3 ± 0.5) at 2.5 degrees compared with PanOptix (4.3 ± 0.4), AT Lisa Tri (2.1 ± 0.1), and monofocal IOLs yielding minimal or no increase.

CONCLUSIONS

Trifocal IOLs induced increased straylight, but it was limited to lower angles, which may cause difficulties detecting these effects using a standard clinical approach. The latest IOL designs featuring chromatic aberration correction at far focus seem more susceptible than the established trifocal IOLs to inducing a glare phenomenon.

Comparison of the optical behaviour of five different multifocal diffractive intraocular lenses in a model eye

The purpose of this study was to investigate and compare the optical performance of five trifocal intraocular lenses (IOLs) following the ISO 11979-2 standards, analysing the impact of tilt and decentration. Five different diffractive trifocal IOLs were evaluated in this experimental study: Acriva Trinova (VSY-Biotechnology) (AT), FineVision HP (PhysIOL) (FVHP), AT LISA tri 839 MP (Zeiss) (ATLT), PanOptix TFNT00 IOL (Alcon) (PO), and Tecnis Synergy (J&J Vision) (TS). In-vitro optical quality analysis of them was performed with the Lambda PMTF system that has an aberration neutral cornea model (Lambda-X Ophthalmics). Measurements were performed on-axis, with 5º of IOL tilt and with 0.5 mm of IOL decentration using 543-nm monochromatic light. Finally, IOL dimensions and diffractive disk profile inspection was performed using the VisIOLA system (Rotlex). On-axis measurements showed a far through-focus MTF > 0.3 at 3 mm aperture, except for TS. FVHP and PO showed better far MTFs for larger apertures (3.75 mm and 4.5 mm) while AT showed good intermediate and near vision for such apertures. With 5º of IOL tilt, the better optical performance at all distances was found with AT for medium-sized pupils (3 mm) and an important reduction of MTF was found for ATLT and PO, especially in the intermediate focus. The induction of 0.5 mm of IOL decentration especially affected the intermediate focus of ATLT and TS and the far focus of FVHP and PO. IOL dimensions and diffractive profile were consistent with those described by the manufacturer. In conclusion, there are differences in the optical performance according to the pupil aperture of the five trifocal IOLs evaluated and this should be considered in clinical practice when selecting the most appropriate implant in each specific case. IOL tilt and decentration can affect significantly in most of the designs evaluated the performance of the IOL at intermediate vision range. It should be noted that measurements were made with an aberration-free cornea, being necessary future studies analysing the impact of different levels of corneal aberrations.

One-year follow-up of a multifocal intraocular lens with optimized elevated phase shift

PURPOSE

To evaluate the standard outcomes of a multifocal intraocular lens (mIOL) with optimized elevated phase shift (EPS).

SETTING

Qvision, Ophthalmology Department, VITHAS Almería, Spain.

DESIGN

Retrospective observational.

METHODS

41 patients, consecutively operated on cataracts or refractive lens exchange with the implantation of the Liberty 640PM (EPS 2.0) and followed during 12 months, were included in the analysis. Retrieved variables were visual acuities at far, intermediate, and near distances; defocus curves (VADC); and prediction error of 4 formulas optimized for IOLMaster 500 and Pentacam AXL Wave. Patient-reported outcomes were also obtained for assessing spectacle independence, satisfaction, bothersome to dysphotopsia, difficulties in daily life tasks, and decision to be operated with the same mIOL.

RESULTS

The median monocular efficacy with best distance correction was 0, 0.1, and 0.1 logMAR at far, intermediate, and near distances, respectively, with patients achieving binocularly a median of 0 logMAR at the 3 distances. VADC showed a depth of field of 3 diopters (D) above 0.2 logMAR with a median increase of 0.07 logMAR from -1.5 to -2.5 D. Complete spectacle independence was achieved at far distance, whereas 97.6% and 85.4% was achieved at intermediate and near distances, respectively. 7.3% of patients were bothered by dysphotopsia, and 92.6% of patients were likely to be operated again.

CONCLUSIONS

EPS 2.0 restored patients' vision in the full range of the depth of field with a nearly monotone decrease of visual performance from far to near, achieving high rates of spectacle independence at all distances and with low positive dysphotopsia rates ( ClinicalTrials.gov Identifier: NCT05735990).

Chromatic aberration and spectral dependency of extended-range-of-vision intraocular lens technology

This study compared the optical quality and chromatic performance of refractive-diffractive intraocular lenses (IOLs) that are designed to extend the range of vision of pseudophakic patients and alter chromatic aberration. Five IOLs were evaluated, Tecnis Synergy and Triumf POD L GF, both intended to compensate for eye's chromatism, as well as Acriva Trinova Pro C-a lens that increases chromatic aberration, and AT Lisa Tri and AcrySof IQ PanOptix. An optical setup composed of a corneal model inducing monochromatic and chromatic aberrations and incorporating various spectral conditions was employed. The two chromatic-aberration correcting IOLs demonstrated the lowest far-focus dispersion, but it was negative only, with the Synergy indicating its ability to reduce eye's chromatic aberration. Although the Trinova increased far-point chromatism, it was close to the level of the PanOptix, but higher than that of the AT Lisa. All the studied models demonstrated varying optical quality in response to light color. Still, the strongest spectral dependency was associated with achromatizing technology. Therefore, chromatic aberration and wavelength dependency should be considered in IOL optimization and predicting visual function, particularly in non-white spectral conditions.

The Novel Optical Design and Clinical Classification of a Wavefront-Shaping Presbyopia-Correcting Intraocular Lens

Purpose

To evaluate the clinical rationale of wavefront-shaping technology, describe how intraocular lenses (IOLs) using wavefront-shaping technology are differentiated from refractive or diffractive optical presbyopia-correcting designs, and describe the mode of action of this technology.

Methods

Extended depth of focus (EDoF) IOLs are the latest class of presbyopia-correcting IOLs addressing the growing demand of patients for reduced spectacle dependence. These use various optical technologies, including diffractive designs (eg, TECNIS Symfony ZXR00 and AT LARA 29 MP) and non-diffractive designs such as small aperture (eg, IC-8 IOL and XtraFocus Pinhole Implant), spherical aberration (eg, MINI WELL Ready and LuxSmart), and wavefront shaping (eg, AcrySof IQ Vivity DFT015 and Clareon Vivity CNWET0). Despite some improvement in visual acuity at intermediate and near distances, these technologies can still be associated with increased rate of visual disturbances or poorer distance vision compared with monofocal IOLs. One way to overcome such limitations is using a wavefront-shaping optical principle.

Results

Clinical data show that wavefront-shaping technology results in a continuous EDoF compared with a monofocal IOL while exhibiting a minimal halo, similar to an aspheric monofocal IOL. Clinically, this translates to a lens that has proven to exceed the American National Standards Institute/American Academy of Ophthalmology criteria for an EDoF IOL.

Conclusion

The novel wavefront-shaping optic technology allows patients to achieve a continuous range of vision from distance to functional near with low levels of visual disturbances comparable with aspheric monofocal IOLs.

Spatio-chromatic vision with multifocal diffractive intraocular lens

BACKGROUND

This study aims to detect alterations in the spatio-chromatic pseudophakic vision produced by multifocal diffractive intraocular lenses (IOLs) and provides a physical interpretation.

METHODS

In vitro characterization of the imaging performance of two diffractive IOLs: AT LISA Tri (Zeiss) and FineVision (PhysIOL) in on-bench model eye illuminated with red (R, 625 nm), green (G, 530 nm) and blue (B, 455 nm) lights. We used the metrics: energy efficiency (EE), area under the modulation transfer function, longitudinal chromatic aberration (LCA), and halo intensity. Through-focus (TF) analysis and calculation of the expected defocus curve under white (W) daylight were included. In vivo visual acuity (VA) of 50 pseudophakics (60 eyes) was assessed under W, R, G, B lights at far and near. Two clinical experiments evaluated LCA and R, G, B TF-EE effects on pseudophakic vision and their relative importance.

RESULTS

Clinical mean VA values under W light agreed with the predicted values at far and near for both IOLs. LCA measurements and R, G, B TF-EE curves were consistent with their lens design based on the 0th and 1st diffraction orders operative for far and near vision, respectively. LCA effects were compensated at near but noticed at far (- 0.75 D under B light). We detected strong asymmetry in visual resolution depending on the object distance and the illuminating wavelength-red predominance at far, blue predominance at near-in consistency with the TF-EE measurements.

CONCLUSIONS

Diffractive multifocal IOL designs produce asymmetries in the spatio-chromatic vision of pseudophakics beyond the alterations strictly due to LCA. VA asymmetry for far/near object distance under R and B illumination is clinically detectable in subjects implanted with IOLs with 0th and 1st diffraction orders for far and near vision, respectively. Such VA asymmetry cannot be explained solely from the influence of defocus, as would be derived from a chromatic difference of power, but mainly from the wavelength dependence of the EE.

Comparison of the Polychromatic Image Quality of Two Refractive-Segmented and Two Diffractive Multifocal Intraocular Lenses

Evaluating chromatic aberration for a multifocal intraocular lens (MIOL) in vitro is essential for studying its performance because it helps determine the most appropriate lens for each patient, enhancing surgical outcomes. While refractive MIOLs with angular power variation have shown positive clinical outcomes, studies of these MIOLs on optical benches primarily employed monochromatic green light, neglecting the impact of longitudinal chromatic aberration (LCA) on MIOL performance. To address this gap, we evaluated the through-focus modulation transfer function (TF-MTF) and the point spread function (PSF) of two refractive segmented extended depth of focus intraocular lenses (IOLs) (Femtis Comfort and Precizon Presbyopic), comparing the results with those obtained with two widely known diffractive multifocal intraocular lenses (AcrySof IQ ReSTOR and FineVision Pod F). Measurements of the TF-MTF were conducted using both monochromatic and polychromatic light in a customized optical bench. The refractive designs exhibited distinct haloes in the PSFs. When comparing the refractive and diffractive designs, opposite signs of LCA were observed at near foci. These findings emphasize the influence of the optical design of IOLs on their performance under polychromatic light, providing valuable information for vision care professionals when selecting the most suitable lens for each patient.

Analysis of Wavefront Data Obtained With a Pyramidal Sensor in Pseudophakic Eyes Implanted With Diffractive Intraocular Lenses

PURPOSE

To investigate the clinical validity of using wavefront measurements obtained with a recently available pyramidal aberrometer to assess the optical quality of eyes implanted with diffractive intraocular lenses (IOLs).

METHODS

Individual biometric data were used to create models of pseudophakic eyes implanted with two diffractive IOLs. Their synthetic wavefronts were calculated by ray-tracing with near infrared wavelength (0.85 μm). Comparisons of the through-focus visual acuity of 12 pseudophakic eyes were obtained with three different methods: clinical defocus curves; simulated defocus curves calculated from ray-tracing in the customized model eyes; and through-focus simulated defocus curves calculated from the wavefront data measured with a pyramidal aberrometer.

RESULTS

Image quality calculated from wavefront data obtained by ray-tracing with 0.85 μm wavelength, without scaling the phase to 0.55 μm, resulted in a significantly different through-focus curve compared to the reference values. Even so, after scaling of the wavefront data to 0.55 μm, the defocus curves calculated from the wavefronts measured with the pyramidal aberrometer did not match the shape and the depth of field of the clinical defocus curves or the theoretical expected values.

CONCLUSIONS

Correcting for the longitudinal chromatic aberration of the eye when measuring the wavefront of eyes implanted with diffractive IOLs under near infrared light only accounts for the best focus shift due to the longitudinal chromatic aberration, but not for the wavelength dependence of the diffractive element. The pyramidal sensor does not seem to properly sample the slopes of a wavefront measured from a pseudophakic eye implanted with a presbyopia-correcting diffractive IOL to a clinically acceptable level. [J Refract Surg. 2023;39(7):438-444.].

Comparison of Five Presbyopia-Correcting Intraocular Lenses: Optical-Bench Assessment with Visual-Quality Simulation

Presbyopia correction through implantation of a trifocal intraocular lens (IOL) is a modality offered to both cataract and refractive-lens exchange patients. To maximize postoperative satisfaction, IOL selection needs to be made based on patients’ requirements aligned with the available technology. Five Trifocal IOLs were assessed in this study, and their differentiating features were identified: Triumf POD L GF, AT Lisa Tri, Tecnis Synergy, AcrySof IQ PanOptix, and Acriva Trinova Pro C. The optical quality was assessed using the modulation-transfer-function principle. Simulated defocus curves were derived from a non-linear formula. Far-focus simulated visual acuity (simVA) was 0.03 logMAR or better for all the studied IOLs, showing minimal differences. However, each IOL’s intermediate focus position differed across a range from 61 cm to 80 cm; and for the near focus, it was 36 cm to 44 cm. Triumf demonstrated improved intermediate point at the expense of the near focus resulting in a lower predicted near VA. PanOptix exhibited the shortest range of vision without a clear distinction between intermediate and near-point. The remaining lenses presented three foci of comparable optical quality and, thus, simVA performance. Each model, however, revealed a different aperture-change response. Trinova function improved at intermediate but was worse at near for larger pupils. The opposite was observed for AT Lisa. Synergy’s optical quality change was predominantly associated with lower pupil diameter. In conclusion, the trifocal IOLs can be differentiated according to their secondary-foci position, light-energy distribution, and pupil-size-related behavior. The observed differences may translate directly into a clinical effect showing that the trifocal IOLs vary in their ability to deliver optimal vision at different distances, with some providing improved intermediate while others favor reading distance. The knowledge gained through this objective testing can support IOL selection, postoperative patient counselling and increase the chance of spectacle independence after surgery.

Pitfalls of Using NIR-Based Clinical Instruments to Test Eyes Implanted with Diffractive Intraocular Lenses

The strong wavelength dependency of diffractive elements casts reasonable doubts on the reliability of near-infrared- (NIR)-based clinical instruments, such as aberrometers and double-pass systems, for assessing, post-surgery, the visual quality of eyes implanted with diffractive multifocal intraocular lenses (DMIOLs). The results obtained for such patients when using NIR light can be misleading. Ordinary compensation for the refractive error bound to chromatic aberration is not enough because it only considers the best focus shift but does not take into account the distribution of light energy among the foci which strongly depends on the wavelength-dependent energy efficiency of the diffractive orders used in the DMIOL design. In this paper, we consider three commercial DMIOL designs with the far focus falling within the range of (−1, 0, +1)-diffractive orders. We prove theoretically the differences existing in the physical performance of the studied lenses when using either the design wavelength in the visible spectrum or a NIR wavelength (780 to 850 nm). Based on numerical simulation and on-bench experimental results, we show that such differences cannot be neglected and may affect all the foci of a DMIOL, including the far focus.

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

INTRODUCTION

This study was performed to compare the optical performance of a multizonal presbyopia-correcting intraocular lens (IOL) and a conventional trifocal model.

METHODS

The optical quality and simulated visual acuity (VA) of 570 Precizon Presbyopic NVA (OPHTEC BV) and AcrySof IQ PanOptix (Alcon) were compared. The Precizon features a refractive design consisting of alternating optical zones that converge the incident light into two principal foci and a transitional zone for intermediate vision. By contrast, the PanOptix applies a diffractive (non-apodized) profile to achieve trifocality. Simulated VA was derived from the modulation transfer function. Chromatic aberration effects were also studied.

RESULTS

The diffractive and multizonal-refractive lenses yielded comparable simulated VAs at far focus (0.00 logMAR). All curves showed a reduction in expected VA with an increase in negative defocus. At - 1.0 D, the multizonal-refractive IOL's VA dropped by 0.05 logMAR, but for the diffractive model, it was one line (0.11 logMAR). The multizonal-refractive lens's VA prediction at the secondary peak was 0.03 logMAR-minimally better than the 0.06 logMAR of the diffractive lens at - 2.5 D. The refractive lens exhibited a 24% decrease in polychromatic optical quality due to material dispersion. The performance of PanOptix was more substantially affected, showing a 44% loss at 50 lp/mm at far, with minimal effects at other distances.

CONCLUSION

The multizonal-refractive lens does not fall short of the established trifocal IOL, and it can be used to extend the visual range of pseudophakic patients. Although the multizonal-refractive lens has lower material dispersion, the diffractive model corrects chromatism beyond far focus.

Theoretical model and optimization of diffractive optical elements with aspheric substrates in ophthalmology

Diffractive optical elements (DOEs), which can produce arbitrary light distribution, are widely applied in ophthalmic lens design with spheric substrates. However, diffraction substrates tend to be designed as aspheric surfaces to eliminate aberrations. In this case, the diffraction theory of plane substrates is no longer accurate, which affects the diffraction performance. Therefore, a diffraction theory of aspheric diffraction substrates is proposed in this paper. Using the range of common parameters for aspheric substrates in ophthalmology, the influence of the substrate diopter and the aspheric surface parameters on the period radius and phase delay is analyzed. Then, through a design example of a diffraction intraocular lens (IOL), an optimization equation is proposed and discussed. The results show that the diffraction theory of aspheric substrates and the optimization equation model can analyze and reduce the effect of aspheric diffraction substrates. This research can be used in DOE design with aspheric substrates in ophthalmology.

Characterization of diffractive bifocal intraocular lenses

Multifocal intraocular lenses incorporate a variety of design considerations, including dimensioning of the base monofocal shape and the diffraction grating. While studying three different lens models, we present a practical approach for mathematical modelling and evaluation of these geometries. Contrary to typical lens measurement methods, non-contact measurements were performed on the Alcon SN6AD1, HumanOptics MS 612 DAY and the AMO ZMA00 lenses using a confocal microscope. Subsequent data processing includes centering, tilting correction, filtering and an algorithmic decomposition into a conic and polynomial part and the diffraction grating. Lastly, evaluation of fitting parameters and grating shape is done to allow for inferences about further optical properties. Results and analysis show the confocal microscope to be a suitable imaging method for lens measurements. The processing of this data enables the reconstruction of the annular diffraction grating over the complete lens diameter. Apodization, near addition and diffraction efficiency characteristics are found utilizing the grating shape. Additionally, near-optical axis curvature, asphericity and higher order polynomials are identified qualitatively from the reconstruction of the monofocal base form. Derived properties also include the lens optical base and addition power. By making use of the surface geometries, as well as the lens' material and thickness, a full lens model can be created for further studies. In summary, our analytical approach enables the insight to various intraocular lens design decisions. Furthermore, this procedure is suitable for lens model creation for research and simulation.

Geometric-phase intraocular lenses with multifocality

We demonstrate a new type of multifocal and extended depth of focus (EDOF) intraocular lenses (IOLs) embedding μm-thin geometric phase (GP) lens layers. As an emerging approach for lens phase design, the GP modulated IOLs outperform conventional diffractive IOLs in multifocality while completely avoiding the clinically undesirable demand for additional surface patterns to standard monofocal IOL designs. The number of foci and light splitting ratio of the GP IOLs are adjusted by changing the number of stacked GP layers and the thickness of each layer. Bifocal and trifocal GP IOLs are fabricated by radial alignment of anisotropic orientation in UV-curable liquid crystal polymers. After characterizing the defocus image and modulation transfer function of the GP IOLs, it is expected that GP IOLs will alleviate the most common problems associated with multifocal and EDOF IOLs, blurred vision and photic phenomena caused by light scattering and posterior capsule opacification.

Understanding In Vivo Chromatic Aberrations in Pseudophakic Eyes Using on Bench and Computational Approaches

Diffractive multifocal intraocular lenses (IOLs) modulate chromatic aberration and reduce it at certain distances due to interactions between the refractive and diffractive chromatic components. However, the extent to which computer modeling and on bench measurements of IOL chromatic aberration translate to chromatic aberration in patients implanted with these multifocal IOLs (MIOLs) is not yet fully understood. In this study, we compare the chromatic difference of focus and longitudinal chromatic aberrations in pseudophakic patients implanted with different IOL designs (monofocal and trifocal IOLs) and materials (hydrophobic and hydrophilic), and compared them with predictions from computer eye models and on bench measurements with the same IOLs. Patient data consisted of results from 63 pseudophakic eyes reported in four different studies and obtained psychophysically in the visual testing channel of a custom-developed polychromatic adaptive optics system. Computational predictions were obtained using ray tracing on computer eye models, and modulation transfer function (MTF) on bench measurements on physical eye models. We found that LCA (in vivo/simulated) for far vision was 1.37 ± 0.08 D/1.19 D for monofocal hydrophobic, 1.21 ± 0.08 D/0.88 D for monofocal hydrophilic, 0.99 ± 0.06 D/1.19 D for MIOL hydrophobic, and 0.82 ± 0.05 D/0.88 D for MIOL hydrophilic. For intermediate and near vision, LCA (in vivo/simulated) was 0.67 ± 0.10 D/0.75 D and 0.23 ± 0.08 D/0.19 D for MIOL hydrophobic and 0.27 ± 0.15 D/0.38 D and 0.15 ± 0.15 D/−0.13 D for MIOL hydrophilic, respectively. In conclusion, computational ray tracing and on bench measurements allowed for evaluating in vivo chromatic aberration with different materials and designs for multifocal diffractive intraocular lenses.

Polychromatic Assessment of a Refractive Segmented EDOF Intraocular Lens

This study aimed to evaluate in vitro performance refractive segmented EDOF intraocular lenses under polychromatic light using an optical bench that complies with the ISO 11979-2 Norm. The through focus modulation transfer function (TF-MTF) of the Femtis Comfort LS-313 MF15 (Oculentis GmbH, Berlin, Germany) IOL was evaluated for IOLs with three different base powers. The effect of the asymmetry of the segmented designs was evaluated with 3 different wavelengths and with polychromatic light at a 3.0 mm and 5.0 mm pupil diameter. It was demonstrated that the TF-MTF curves exhibit a bifocal profile that, in practice, results in an EDOF design. As a consequence of the LCA, the TF-MTF values in white light were lower than in monochromatic light. Images of the USAF test chart were obtained to confirm the prediction of the TF-MTFs. We found that Femtis Comfort is a bifocal low-addition IOL and this fact can result in an EDOF effect which was obtained previously in clinical trials. Moreover, we showed that the base power influences the IOL optical quality, which results as more effective for high powers (hyperopic eyes) than for low powers (myopic eyes). The LCA of the segmented refractive design was very low and presumably not clinically relevant.

In Vitro Chromatic Performance of Three Presbyopia-Correcting Intraocular Lenses with Different Optical Designs

Most of the new premium models of intraocular lenses for presbyopia correction use diffractive optics in their optical design. The presence of multiple foci and the difference of the diffractive efficiency for different wavelengths have a great impact in the lens optical performance. In this context, there is a limited information available for clinicians to understand the optical principles that differentiate each design and their potential influence on clinical outcomes. Optical bench studies with polychromatic light are necessary to solve this limitation. In this work, a custom made optical bench was employed to assess with polychromatic light the through the focus optical quality of three different IOL designs: trifocal, EDOF effect; and enhanced monofocal. By using different and complimentary approaches: images of the USAF test, axial PSFs and TF-MTFs, each design revealed its intrinsic features, which were not previously reported for these IOLs models in a comparative way. It was found that the chromatic aberration plays a very important role in the performance of each IOL. Our results could help clinicians to understand the optical principle of each lens and also provide useful information for choosing the lens that best suits the needs of the individual patient.

Laboratory and Clinical Experience With a Diffractive Trifocal Intraocular Lens Sutured to an Artificial Iris

PURPOSE

To determine in vitro, using a translational research approach before realizing the procedure in a patient with iatrogenic aphakia and partial aniridia, whether suturing a trifocal intraocular lens (IOL) to an artificial iris degrades the IOL's optical quality.

METHODS

Optical quality was analyzed by measuring the modulation transfer function (MTF) at a 3-mm aperture and at 50 and 100 lp/mm spatial frequencies. The FineVision Pod F GF IOL (PhysIOL) was assessed in two powers: two +20.00 diopters (D) (20A and 20B IOLs) and two +30.00 D (30A and 30B IOLs). The IOLs' decentration in relation to the artificial iris's center was evaluated. The laboratory results provided empirical evidence in the informed consent for surgical intervention in a patient with iatrogenic aphakia and iris defect in one eye. Clinical results were measured using the parameter of corrected distance visual acuity plus a patient self-assessment of the cosmetic appearance of the operated eye.

RESULTS

The 20A and 20B IOLs demonstrated a mean MTF reduction of up to 1.1%, whereas the 30A and 30B IOLs showed a decrease of up to 5.2% for both spatial frequencies. All lenses showed good centration levels. In the clinical case, the patient showed corrected distance visual acuity, distance-corrected near visual acuity, and distance-corrected intermediate visual acuity of 0.20, 0.20, and 0.22 logMAR, respectively. The patient was satisfied with the cosmetic outcome.

CONCLUSIONS

There was merely a slight reduction in trifocal IOL optical quality after it was sutured to an artificial iris. Clinically, the combined implantation of the artificial iris and FineVision IOL provided good functional and cosmetic outcomes. [J Refract Surg. 2022;38(1):61-68.].

Changes in Optical Quality Induced by Tilt and Decentration of a Trifocal IOL and a Novel Extended Depth of Focus IOL in Eyes With Corneal Myopic Ablations

PURPOSE

To assess the effect of decentration and tilt combined with prior myopic ablations on the optical performance of a trifocal intraocular lens (IOL) and a novel IOL with an extended depth of focus (EDOF) design.

METHODS

The XACT Mono-EDOF ME4 (Santen Pharmaceutical Co Ltd) and the trifocal FineVision (PhysIOL) IOLs were analyzed with and without simulated previous myopic ablations. The optical quality of the IOLs was evaluated with the PMTF optical bench (LAMBDA-X). The through-focus modulation transfer function (MTF) curves were recorded. Measurements were done for three situations: centered, 0.4 mm decentered, and 4 degrees tilted.

RESULTS

The trifocal IOL showed three peaks of vision and the EDOF IOL showed a far distance peak with intermediate addition. When decentration or tilt were induced, the trifocal IOL showed negligible changes but the EDOF IOL showed a -0.50 diopters (D) shift of the overall curve. With simulated myopic ablation, the trifocal IOL showed a -0.50 D shift of the curve. When tilt or decentration were also induced, the better optical results were found at -1.00 D. With myopic ablations, the EDOF IOL showed a -0.50 D shift of the optical quality and when decentration or tilt were then induced, negative shifts over -1.00 D were found.

CONCLUSIONS

The trifocal IOL was less affected by mis-alignments. When myopic ablations were induced, both lenses decreased their optical quality and the effects of misalignments were higher. In patients who have undergone corneal myopic ablation procedures, proper alignment of the implanted IOL and obtaining effective emmetropia becomes even more critical. [J Refract Surg. 2021;37(8):532-537.].

Impact of Lens Material on Objective Refraction in Eyes with Trifocal Diffractive Intraocular Lenses

Purpose: Compare subjective (Rx) and objective (ObjRx) refractions outcomes with two autorefractors models and an aberrometer in eyes implanted with a hydrophobic trifocal IOL (FineVision POD F GF, Physiol, Liége, Belgium) and a hydrophilic one (FineVision POD F, Physiol, Liége, Belgium).Methods: Prospective comparative cohort study, with 100 subjects randomly assigned to either the POD F group (n = 50) or the POD F-GF group (n = 50). Postoperative eye examinations at 1-month visit included seven result sets, one for each assessment method: Rx, AR (automated refraction measured with the autorefractor KR8800), WF-P (Zernike-coefficients-based objective refraction, photopic pupil size), WF-M (Zernike-coefficients-based objective refraction, mesopic pupil size), WF-4 (Zernike-coefficients-based objective refraction, 4 mm pupil), OPD-C (automated refraction measured with the aberrometer OPD in the central pupil/photopic conditions), and OPD-M (automated refraction measured with the aberrometer OPD under mesopic conditions).Results: Mean differences between ObjRx and Rx reached statistical significance for sphere and spherical equivalent (M) only with OPD-C in the POD F-GF group. All ObjRx methods showed significant differences with Rx in the POD F group, with some values differing by more than 0.50 D (-0.58 D in M for the WF-P). Bland Altman plots showed better agreement for the astigmatic components, and for sphere and spherical equivalents in both IOL groups measured with AR and OPD-M.Conclusions: None of the objective methods of refraction evaluated in this study were as reliable as the subjective refraction, irrespective of the lens material, but POD F-GF ObjRx seems to differ less with Rx than POD F ObjRx values.

Optical design and performance of a trifocal sinusoidal diffractive intraocular lens

Two theoretical sinusoidal diffractive profile models to build up a trifocal intraocular lens (IOL) are analysed. Topographic features of the diffractive zones such as their shape, step height and radii, as well as the energy efficiency (EE) of the foci, depends on the particular model, and are compared to the ones experimentally measured in a trifocal lens that claims to be designed with a generic sinusoidal diffractive profile: the Acriva Trinova IOL (VSY Biotechnology, The Netherlands). The topography of the IOL is measured by confocal microscopy. The EE is experimentally obtained through-focus with the IOL placed in a model eye. The experimental results match very accurately with one of the theoretical models, the optimum triplicator, once that a spatial shift in the sinusoidal profile is introduced in the model.

Visual performance of four types of diffractive multifocal intraocular lenses and a review of articles

AIM

To compare the clinical outcomes of a variety of multifocal intraocular lenses (MIOLs) in patients diagnosed with presbyopia or cataracts.

METHODS

This clinical trial study included 141 patients (282 eyes) with different MIOLs implantation. The Symfony (60 eyes), the ReSTOR (100 eyes), the AT LISAtri (60 eyes), and the PanOptix (62 eyes) intraocular lenses were evaluated in this prospective interventional study. The near, intermediate, and distant visual acuities, contrast sensitivity, and defocus curve were measured as valid criteria. To statistically analyze the results, we used the Statistical Package for Social Science software, the non-parametric Wilcoxon signed-rank t, the one-way analysis of variance and the Tukey's post-hoc test in our analysis. Moreover, we conducted a detailed literature search on the PubMed database in English about MIOLs, in total 59 studies were included in this review article.

RESULTS

The four approaches did not show any significant difference in the best-corrected distance visual acuity (P>0.05). The defocus curves at the contrast of 100% showed that trifocal IOLs had better intermediate performance than the bifocal IOL (P<0.05). There were no statistically significant differences between AT LISAtri and PanOptix lenses for visual acuity at all distances. The eyes with PanOptix, Symfony, and AT LISAtri IOL showed better contrast sensitivity than those ReSTOR at spatial frequencies of 1, 3, and 6 cpd in photopic and mesopic conditions (P<0.001).

CONCLUSION

All four groups of the multifocal lenses were satisfying in terms of distance and near vision. Also, the group of trifocal lenses led to satisfactory outcomes in intermediate vision, without degradation in quality of vision.

Through-Focus Energy Efficiency and Longitudinal Chromatic Aberration of Three Presbyopia-Correcting Intraocular Lenses

Purpose

To compare the chromatic performance of the Bausch & Lomb Versario 3F trifocal intraocular lens (IOL) with the PhysIOL FineVision MicroF trifocal IOL and the Johnson & Johnson Vision TECNIS Symfony ZXR00 extended range of vision (ERV) IOL.

Methods

The through-focus energy efficiency (TF-EE) was measured in vitro with red (R), green (G), and blue (B) wavelengths and was used to obtain the focus powers and longitudinal chromatic aberrations (LCAs) for each IOL. Other metrics, derived from the RGB TF-EE curves, were assessed for a more complete description of the chromatic performance of the IOLs.

Results

Both of the trifocal IOLs, although not specifically designed to tackle chromatic aberrations, showed acceptable LCA (≤0.50 D) in all foci with more balanced R and B efficiencies of their foci. Despite having the lowest TF-EE value at all foci, the Versario 3F demonstrated the most balanced chromatic performance with the smoothest energy transition among all foci and the smallest chromatic span. The Symfony lens effectively reduced LCA at distance and intermediate foci (≤0.36 D), despite the unbalanced and asymmetric R and B efficiencies at its foci.

Conclusions

To fully describe the chromatic performance of an IOL it is necessary to take into account not only the LCA but also the RGB TF-EE and chromatic span. This comprehensive analysis suggests that, in comparison with the other IOLs under study, the Versario 3F lens might contribute to further mitigating the impact of chromatic aberration.

Translational Relevance

The in vitro bench testing of the optical properties of modern presbyopia-correcting intraocular lenses (more specifically in this work, the polychromatic through-focus energy efficiency and longitudinal chromatic aberration) provides objective and complementary information that helps to interpret the visual quality outcomes of pseudophakic patients obtained in clinics.

Straylight in Different Types of Intraocular Lenses

Purpose

To show the importance of measuring the angular distribution of straylight as an in vitro test for intraocular lenses (IOLs).

Methods

The optical integration method was implemented to measure the point spread function, up to 5.1°, of IOLs immersed in a wet cell. The straylight parameter was calculated as the product of the point spread function by the squared angle. The effect of the scattered light is shown in extended images of a target surrounded by headlamps as glare sources. Three different IOLs were tested: (1) AcrySof IQ SN60WF, monofocal, (2) AcrySof IQ PanOptix, trifocal, and (3) Tecnis Symfony ZRX00, bifocal with extended depth of focus. Measurements were compared to previously reported clinical studies where the same IOL models were implanted.

Results

The mean amount of scattered light, between 1.0° and 5.1°, generated by each IOLs were, in deg²sr^{- 1} units: (1) 1.2, (2) 12.1, and (3) 33.4. Lens (3) present a high amount of straylight related to a halo of an approximate diameter of 2°.

Conclusions

In vitro measurements of the angular distribution of the point spread function of different types of IOLs showed important aspects related to their manufacturing quality. These results are in line with previous clinical findings where glare sensitivity was tested in the same angular range.

Translational Relevance

In vitro measurement of angular dependence of straylight in IOLs, regardless their design, provides a valuable feedback to improve their optical quality. The minimization of the amounts of straylight positively impacts the recurrence of photic phenomena.

Multifocal and Extended Depth-of-Focus Intraocular Lenses in 2020

Ophthalmic surgeons have been overwhelmed by the influx of multifocal intraocular lens (IOL) options in recent years, with close to 100 IOLs on the market in 2020. This practical and technical update on a representative group of established as well as newly launched multifocal IOLs on the market focuses on multifocal IOLs, including extended depth-of-focus lenses. We also describe the optical basis of lens platforms used and thorough preoperative planning to aid decision making. This allows the surgeon the knowledge base to deliver the required relative customized spectacle independence with the least photic phenomenon and loss of contrast possible while achieving high individual patient satisfaction. Data of reviewed IOLs displayed in tabular format include mean monocular uncorrected distance, intermediate, and near visual acuities (logarithm of the minimum angle of resolution), with standard deviations and ranges where available. The range of vision targeted, pupil dependence, toric availability, as well as type of optical platform, are provided as a practical guide to demystify existing terminology on the market that may create interest around a seemingly new design that is actually not novel at all. Halos and glare experienced, levels of patient satisfaction, and spectacle independence achieved also are summarized. A wide range of multifocal IOLs options are available on the market to surgeons. Comprehensive patient selection and examination, combined with knowledge of the most recent options and adequate patient counseling, including neuroadaptation, can avoid dissatisfaction. Many recently available IOLs are awaiting formal results, but the methods by which we label and compare these types of IOLs must also be standardized.

Total Depth of Focus of Five Premium Multifocal Intraocular Lenses

PURPOSE

To compare the in vitro optical performance of five premium multifocal intraocular lenses (IOLs), including a single-valued metric that shows the total range of distances where a multifocal IOL generates an acceptable image quality.

METHODS

Through-focus modulation transfer function (MTF) and the image of a United States Air Force target were obtained for a 3-mm pupil and a wavelength of 546 nm in five multifocal IOLs (Tecnis Symfony [Johnson & Johnson], FineVision Micro F [PhysIOL], Acrysof IQ PanOptix [Novartis], and Artis Symbiose Mid and Plus [Cristalens Industrie] multifocal IOLs). Total depth of focus (TDOF) is computed by adding the vergence intervals where the through-focus MTF at 50 cycles/mm is 0.15 or greater.

RESULTS

Due to their different optical designs (bifocal, trifocal, or extended depth of focus), energy is distributed differently between far, intermediate, and near focus for each multifocal IOL. The light distribution of the Symbiose Mid and Plus multifocal IOLs was similar, concentrating the energy into far focus and the intermediate into near focus, but extending the intermediate focus more (Plus) or less (Mid) toward the near focus. TDOFs were: 1.58 diopters [D] (FineVision); 1.71 D (Tecnis Symfony); 1.73 D (Artis Symbiose Plus); 1.74 D (Artis Symbiose Mid); and 1.90 D (Acrysof IQ PanOptix).

CONCLUSIONS

TDOFs were similar between multifocal IOLs with a maximum difference of 0.32 D and mean value of 1.73 D. The combination of the Symbiose Mid and Plus IOLs can theoretically provide a TDOF of 2.90 D in case one is implanted in one eye and the other in the fellow eye. [J Refract Surg. 2020;36(9):578-584.].

Testing the effect of ocular aberrations in the perceived transverse chromatic aberration

We have measured the ocular transverse chromatic aberration (TCA) in 11 subjects using 2D-two-color Vernier alignment, for two pupil diameters, in a polychromatic adaptive optics (AO) system. TCA measurements were performed for two pupil diameters: for a small pupil (2-mm), referred to as 'optical TCA' (oTCA), and for a large pupil (6-mm), referred to 'perceived TCA' (pTCA). Also, the TCA was measured through both natural aberrations (HOAs) and AO-corrected aberrations. Computer simulations of pTCA incorporated longitudinal chromatic aberration (LCA), the patient's HOAs measured with Hartmann-Shack, and the Stiles-Crawford effect (SCE), measured objectively by laser ray tracing. The oTCA and the simulated pTCA (no aberrations) were shifted nasally 1.20 arcmin and 1.40 arcmin respectively. The experimental pTCA (-0.27 arcmin horizontally and -0.62 vertically) was well predicted (81%) by simulations when both the individual HOAs and SCE were considered. Both HOAs and SCE interact with oTCA, reducing it in magnitude and changing its orientation. The results indicate that estimations of polychromatic image quality should incorporate patient's specific data of HOAs, LCA, TCA & SCE.

Equivalence of two optical quality metrics to predict the visual acuity of multifocal pseudophakic patients

This article studies the relationship between two metrics, the area under the modulation transfer function (MTFa) and the energy efficiency (EE), and their ability to predict the visual quality of patients implanted with multifocal intraocular lenses (IOLs). The optical quality of IOLs is assessed in vitro using two metrics, the MTFa and EE. We measured them for three different multifocal IOLs with parabolic phase profile using image formation, through-focus (TF) scanning, three R, G, B wavelengths, and two pupils. We analyzed the correlation between MTFa and EE. In parallel, clinical defocus curves of visual acuity (VA) were measured and averaged from sets of patients implanted with the same IOLs. An excellent linear correlation was found between the MTFa and EE for the considered IOLs, wavelengths and pupils (R² > 0.9). We computed the polychromatic TF-MTFa, TF-EE, and derived mathematical relationships between each metrics and clinical average VA. MTFa and EE proved to be equivalent metrics to characterize the optical quality of the studied multifocal IOLs and also in terms of clinical VA predictability.