Intraocular Lens Design Research Articles

Differences in visual quality with orientation of a rotationally asymmetric bifocal intraocular lens design

To evaluate visual and perceptual performance for different orientations of a rotationally asymmetric bifocal intraocular lens (IOL) (M-Plus) simulated optically using a simultaneous vision simulator. Instituto de Optica, Madrid, Spain. Prospective observational study. Perceptual quality and decimal high-contrast visual acuity (HCVA) was measured under cycloplegia for 8 orientations of the asymmetric bifocal IOL phase pattern at far, intermediate, and near distances simulated with a simultaneous vision simulator using face images and tumbling E targets. The preferred orientation at each distance was calculated as the centroid of the data for 8 orientations. The visual Strehl value was calculated using the subjects' ocular aberrations and multifocal pattern at each orientation. Optical predictions were obtained by implementing a differential visual Strehl values-based ideal observer model. The study comprised 20 subjects (aged 21 to 62years). Horizontal orientation (near segment at 0 or 180 degrees±45 [SD]) was preferred by 14 subjects and by 13 subjects at far and near distances, respectively; 8 subjects showed strong orientation preferences. The mean difference in preferred orientation between far and near was 27±22 degrees. No significant differences in HCVA were observed. Optical predictions correlated strongly and significantly with measurements (far r=0.71, near r=0.62; P<.0001). The mean difference between measurement and simulation in the preferred orientation was 28±29 degrees at far and 36±28 degrees at near. The perception varied for different orientations of an asymmetric bifocal IOL design tested using a simultaneous vision simulator. Optimum orientation was driven by interactions of the design with the eye's optical aberrations. None of the authors has a financial or proprietary interest in any material or method mentioned.

Key Developments for Partial Coherence Biometry and Optical Coherence Tomography in the Human Eye Made in Vienna.

To describe key developments of optical biometry and optical coherence tomography (OCT) for ophthalmic applications made by one of the pioneering research groups. Partial coherence interferometry (PCI) as the basic ranging technology for modern optical biometry and for OCT was introduced for biomedical applications in the 1980s. Later, Fourier domain (FD) OCT was introduced and demonstrated to provide superior sensitivity as compared to time domain OCT. Further developments comprised ultrahigh-resolution OCT and deep-penetration OCT at wavelengths of approximately 1050 nm. Important functional extensions comprise Doppler OCT/OCT angiography, polarization-sensitive OCT, and adaptive optics OCT. High-precision PCI biometry has found extensive applications in cataract surgery and in research on intraocular lens design. Optical coherence tomography, especially in the second-generation variant of FD OCT, is now indispensable for ocular diagnostics in general and for retinal diagnostics in particular; 1050 nm OCT shows improved penetration into deeper layers like the choroid. The contributions of the Vienna research group helped to establish PCI biometry and FD OCT as the gold standards in their respective fields.

Evaluation of intraocular lens position during phacoemulsification using intraoperative spectral-domain optical coherence tomography

To assess the position of intraocular lenses (IOLs) at the end of standard phacoemulsification with intraoperative spectral-domain optical coherence tomography (SD-OCT). Department of Ophthalmology, Rudolf Foundation Hospital, Vienna, Austria. Prospective case series. Standard phacoemulsification with IOL implantation was performed. The Rescan 700SD-OCT system was used for intraoperative imaging. The anterior segment of the eye was scanned using SD-OCT at the end of the surgery. The distance from the IOL optic center and the IOL optic edge to the posterior capsule was measured postoperatively using graphic software. The study comprised 74 patients (101 eyes). The mean axial length was 23.97mm (range 21.43 to 28.61mm). The mean IOL power was 20.39 diopters (D) (range 6.5 to 27.5 D). Contactbetween the IOL and posterior capsule was absent in 88 cases (87.13%), and partial or full contact was present in 13 cases (12.87%). The mean distance between the IOL central optic and posterior capsule was 0.71 pixel (range 0.06 to 1.38 pixels) in 99 cases (98.02%). In 42 cases (57.53%), partial contact between the IOL edges and the posterior capsule was noticed. The mean distance between the IOL edge and posterior capsule was 0.21 pixel (range 0.04 to 0.92 pixel). Intraoperative SD-OCT facilitated the imaging of IOL position during standard phacoemulsification. Contact between the IOL central optic and posterior capsule at the end of the surgery occurred rarely. Improved IOL design should be considered. Drs. Binder and Glittenberg are consultants to Carl Zeiss Meditech AG. None of the other authors has a financial or proprietary interest in any material or method mentioned.

Impact of low mesopic contrast sensitivity outcomes in different types of modern multifocal intraocular lenses.

To investigate the low mesopic contrast sensitivity function (LMCSF) of patients implanted with different modern optical bifocal and trifocal designs of multifocal intraocular lenses (mfIOLs). This prospective, comparative, nonrandomized consecutive case series included 180 eyes that underwent cataract surgery. Six groups of eyes were differentiated: group A, eyes with the diffractive AT LISA tri 839MP; group B, eyes with diffractive FineVision; group C, eyes with the bifocal Lentis Mplus-LS313; group D, eyes with the diffractive bifocal Acri.Lisa 366D; group E, eyes with the diffractive apodized Acrysof ReSTOR SN6AD1; group F, as the control group, implanted with a monofocal spherical intraocular lens. The LMCSF was evaluated with the OPTEC® 6500 device at 3 months postoperatively using a luminance of 3 cd/m2. No significant differences among groups were detected in LMCSF for the spatial frequencies of 1.5, 3.0, 6.0, and 12.0 cpd (1.5 cpd: F = 1.81, p = 0.13; 3.0 cpd: F = 1.14, p = 0.14; 6.0 cpd: F = 1.87, p = 0.11; 12.0 cpd: F = 1.26, p = 0.29), but significant differences were found among groups for the spatial frequency of 18 cpd (F = 2.62, p = 0.03). When comparing the groups in pairs, only statistically significant differences were observed between groups E and F for the spatial frequency of 18.0 cpd (t = 3.27, p = 0.03) with better values for group F. No significant differences were observed in LMCSF among the different mfIOLs studied. The third focus of trifocal IOL models did not adversely affect the LMCSF. The ReSTOR SN6AD1 showed the poorest LMCSF for the highest spatial frequency analyzed when compared with the control group.

Growth factor restriction impedes progression of wound healing following cataract surgery: identification of VEGF as a putative therapeutic target.

Secondary visual loss occurs in millions of patients due to a wound-healing response, known as posterior capsule opacification (PCO), following cataract surgery. An intraocular lens (IOL) is implanted into residual lens tissue, known as the capsular bag, following cataract removal. Standard IOLs allow the anterior and posterior capsules to become physically connected. This places pressure on the IOL and improves contact with the underlying posterior capsule. New open bag IOL designs separate the anterior capsule and posterior capsules and further reduce PCO incidence. It is hypothesised that this results from reduced cytokine availability due to greater irrigation of the bag. We therefore explored the role of growth factor restriction on PCO using human lens cell and tissue culture models. We demonstrate that cytokine dilution, by increasing medium volume, significantly reduced cell coverage in both closed and open capsular bag models. This coincided with reduced cell density and myofibroblast formation. A screen of 27 cytokines identified nine candidates whose expression profile correlated with growth. In particular, VEGF was found to regulate cell survival, growth and myofibroblast formation. VEGF provides a therapeutic target to further manage PCO development and will yield best results when used in conjunction with open bag IOL designs.

Properties of Silicone fluids before and after purification

Event Abstract Back to Event Properties of Silicone fluids before and after purification Can B. Hu1* and Mike Lowery1* 1 Abbott Medical Optics, United States Introduction: Silicone is a widely used biomaterial[1]. For ophthalmologic applications such as intraocular lenses (IOLs), many properties such as amount of leachables, clarity, refractive index (RI) and viscosity are all important factors for the IOL design. Freshly synthesized high RI silicone fluid usually needs to go through the filtration[2] process to improve the clarity; however, filtration alone can’t remove the low molecular weight species which may leach out after long term implantation. Purification of silicone fluid would be important to remove the undesired low molecular weight species. In this study, properties of silicone fluid before and after purification by solvent washing process are discussed. Material and Methods: High molecular weight silicone with refractive index of 1.47±0.01 was synthesized by anionic ring-opening polymerization[3]-[5]. After filtration through 0.2 µm PTFE filters, silicone fluid was purified by solvent washing process to remove low molecular weight species. Washing process was repeated multiple times (3X and 5X) to check the effect of purification on properties of refractive index (RI), Abbe number, UV-Vis percent transmission (%T), haze level and viscosity. Results: Table 1 shows RI and Abbe number before and after multiple purification process. Although RI of purified silicone fluid was slightly dropped (0.0015 and 0.0019 respectively with 3 and 5 times purification when compared to the filtered control sample only, nevertheless, the difference is significant with p value <0.05 for both purification processes. Abbe number increased slightly after purification. The haze levels before and after purification was summarized in Table 2. It was found that haze level was increased from 2.6 to 3.9 and 5.2 respectively after 3 times and 5 times purification. Although the haze difference of silicone fluid after purification was statistically significant, however, the difference was difficult to tell by naked eyes. It was found that haze level increased with number of purification process. Table 1 and 2. RI, Abbe number and Haze level of silicone fluid before and after purification. An overlap UV/Vis scan of silicone fluid before and after multiple purification process was shown in Figure 1. As in Figure 1, percent transmission (%T) of UV/Vis of purified silicone fluids were also slightly lower than that of non-purified control sample. This observation is consistent with the results of haze study and confirmed our previous study[2]. Figure 1. UV/Vis scans of silicone before and after purification Results of viscosity measurement of silicone fluid before and after purification were summarized in Table 3. It was found that viscosity increased significantly after purification which indicated that low molecular weight species were removed effectively. Table 3. Viscosity of silicone fluid before and after filtration Conclusions: In this study, we found that purification is a very effective method to remove the low molecular weight species of silicone fluid as indicated by the significantly increased the viscosity of silicone fluid. However, other properties such as refractive index, abbe number, haze level and percent transmission of silicone are also impacted by the purification process as well and worth studying further. Thanks approval from Abbott Medical Optics to presented this work SC2015CT0038

Extending the range of vision using diffractive intraocular lens technology

To describe and to experimentally assess a new intraocular lens (IOL) design using new diffractive technology. AMO Groningen b.v., Groningen, Netherlands. Experimental study. The basic principles of the new diffractive technology are described. The new IOL comprises two diffractive technologies; one is designed to extend the range of vision by elongating the focus, and the other increases the retinal image contrast by correcting chromatic aberration. To assess the potential visual performance, simulations were carried out in clinically verified eye models to predict the clinical defocus curves (visual acuity). The optical performance of the new lens design was evaluated by optical measurements in a model eye. The model eye had a cornea having the spherical aberration and chromatic aberration of an average cataract patient. The measurements were performed in white light and monochromatic light. The simulations suggested an increase in visual acuity of 0.27 logMAR as compared to an aspherical monofocal IOL in the range from -1 to -3 diopter defocus. The white light modulation transfer function in the far focus was identical to that of a monofocal IOL. The new lens demonstrated negative chromatic aberration, therefore showing the capability to actively reduce ocular chromatic aberration. The experiments also show retinal image characteristics of an extended light source that suggest that dysphotopsias (halos) of the new IOL are comparable to those associated with monofocal IOLs. The application of new IOL diffractive technology enabled optical characteristics that suggested that an extended range of vision can be obtained without compromising distance vision. All authors are employees of Abbott Medical Optics, Inc.

In vivo subjective and objective longitudinal chromatic aberration after bilateral implantation of the same design of hydrophobic and hydrophilic intraocular lenses

To measure the longitudinal chromatic aberration in vivo using psychophysical and wavefront-sensing methods in patients with bilateral implantation of monofocal intraocular lenses (IOLs) of similar aspheric design but different materials (hydrophobic Podeye and hydrophilic Poday). Instituto de Optica, Consejo Superior de Investigaciones Cientificas, Madrid, Spain. Prospective observational study. Measurements were performed with the use of psychophysical (480 to 700 nm) and wavefront-sensing (480 to 950 nm) methods using a custom-developed adaptive optics system. Chromatic difference-of-focus curves were obtained from best-focus data at each wavelength, and the longitudinal chromatic aberration was obtained from the slope of linear regressions to those curves. The longitudinal chromatic aberration from psychophysical measurements was 1.37 diopters (D) ± 0.08 (SD) (hydrophobic) and 1.21 ± 0.08 D (hydrophilic). From wavefront-sensing, the longitudinal chromatic aberration was 0.88 ± 0.07 D and 0.73 ± 0.09 D, respectively. At 480 to 950 nm, the longitudinal chromatic aberration was 1.27 ± 0.09 D (hydrophobic) and 1.02 ± 0.13 D (hydrophilic). The longitudinal chromatic aberration was consistently higher in eyes with the hydrophobic IOL than in eyes with the hydrophilic IOL (a difference of 0.16 D and 0.15 D, respectively). Similar to findings in young phakic eyes, the longitudinal chromatic aberration from the psychophysical method was consistently higher than from wavefront-sensing, by 0.48 D (35.41%) for the hydrophobic IOL and 0.48 D (39.43%) for the hydrophilic IOL. Longitudinal chromatic aberrations were smaller with hydrophilic IOLs than with hydrophobic IOLs of the same design. No author has a financial or proprietary interest in any material or method mentioned.

Aspherical Lens Design Using Genetic Algorithm for Reducing Aberrations in Multifocal Artificial Intraocular Lens

A complex intraocular lens (IOL) design involving numerous uncertain variables is proposed. We integrated a genetic algorithm (GA) with the commercial optical design software of (CODE V) to design a multifocal IOL for the human eye. We mainly used an aspherical lens in the initial state to the crystalline type; therefore, we used the internal human eye model in the software. The proposed optimized algorithm employs a GA method for optimally simulating the focusing function of the human eye; in this method, the thickness and curvature of the anterior lens and the posterior part of the IOL were varied. A comparison of the proposed GA-designed IOLs and those designed using a CODE V built-in optimal algorithm for 550 degrees myopia and 175 degrees astigmatism conditions of the human eye for pupil size 6 mm showed that the proposed IOL design improved the spot size of root mean square (RMS), tangential coma (TCO) and modulation transfer function (MTF) at a spatial frequency of 30 with a pupil size of 6 mm by approximately 17%, 43% and 35%, respectively. However, the worst performance of spherical aberration (SA) was lower than 46%, because the optical design involves a tradeoff between all aberrations. Compared with the traditional CODE V built-in optimal scheme, the proposed IOL design can efficiently improve the critical parameters, namely TCO, RMS, and MTF.

Halo and Through-Focus Performance of Four Diffractive Multifocal Intraocular Lenses.

To compare, as a function of pupil size, the through-focus performance and halo features of four diffractive intraocular lenses (IOLs). Three diffractive bifocal IOLs (ReSTOR +2.5 D SV25T0, Tecnis +2.75 D ZKB00, and AT LISA +3.75 D 809M) and a diffractive trifocal IOL (AT LISA tri +3.33 D, +1.66 D 839MP) were tested in vitro in a modified International Organization for Standardization eye model. The modulation transfer function (MTF) at the IOLs' foci was obtained with pupils ranging from 2.0 to 5.0 mm. Through-focus MTF curves (at 50 cycles/mm) were compared among all the IOLs. The halo formation and characteristics were obtained from image analysis. The multifocal IOLs studied in this work showed, at their foci, secondary out-of-focus images, which originate halos and whose characteristics depend on the lens design and pupil size. The smallest halo occurred for the distance focus of the SV25T0. The distance and near foci of the SV25T0 yielded, respectively, the best and lowest optical quality among the studied IOLs. The distance focus of the ZKB00, AT LISA, and AT LISA tri were of similar quality, but the near focus of the ZKB00 outperformed the near foci of the rest of the IOLs. The IOLs' optical performance gradually deteriorates as pupil increases. Differences in the design of the diffractive IOLs translate into differences in optical quality at their foci, through-focus performance, and halo features, which can offer further information to surgeons when selecting which IOL to implant.

Optical quality comparison between 2 collagen copolymer posterior chamber phakic intraocular lens designs

To compare the optical quality in vitro of 2 designs of the Visian Implantable Collamer Lens phakic intraocular lens (pIOL) for different powers and optical apertures. University of Valencia, Valencia, Spain. Experimental study. The Nimo TR1504 deflectometry device was used to measure the V4c pIOL, which has a smaller optic diameter, and the V5 pIOL, which has a larger optic diameter. The pIOLs were measured for -3.00 diopters (D), -6.00 D, -9.50 D, and -10.50 D at different optical apertures from 3.00 to 6.00 mm depending on the IOL power and model. The root mean square of higher-order aberrations (RMS HOAs) was analyzed. The Strehl ratio, point-spread functions (PSFs), and simulated images were calculated from wavefront aberrations. There were no statistically significant differences in any Zernike RMS or RMS HOAs between the 2 pIOL models with the same power and optical aperture (P > .05). Both pIOLs had negative spherical aberration that increased with the pIOL power. Strehl ratio values showed no statistically significant differences between the pIOLs with the same power and pupil aperture. Minimal differences were seen in the PSFs and simulated images between the pIOLs. Both pIOLs showed good and comparable in vitro optical quality similar that of a perfect lens in that they should not affect visual performance after implantation. Patients with larger pupil diameters could benefit from the pIOL with the larger optic diameter because it showed better in vitro optical quality than the previous design with a smaller optic diameter. No author has a financial or proprietary interest in any material or method mentioned.

Refraction after Implantation of Multifocal and Presbyopia-Correcting Intraocular Lenses

Nowadays, further developments in the field of intraocular lenses offer a higher level of spectacle independence for our patients. As light gets scattered on different focal points a wider range of defocus is created. This greater defocus area makes it more difficult for us to determine the objective or subjective refraction. This contribution is concerned with the difficulties of measuring visual acuity in different intraocular lens designs and different measurement distances. Measuring refraction after implantation of a multifocal intraocular lens is a complex procedure and the experience of the examiner plays a crucial role. Retinoscopy, keratometry and the defocus curve are reliable methods for testing, while the auto refractometer, bichromatic testing and the cross-cylinder have limitations.

Deformable Surface Accommodating Intraocular Lens: Second Generation Prototype Design Methodology and Testing.

Present an analysis methodology for developing and evaluating accommodating intraocular lenses incorporating a deformable interface. The next generation design of extruded gel interface intraocular lens is presented. A prototype based upon similar previously in vivo proven design was tested with measurements of actuation force, lens power, interface contour, optical transfer function, and visual Strehl ratio. Prototype verified mathematical models were used to optimize optical and mechanical design parameters to maximize the image quality and minimize the required force to accommodate. The prototype lens produced adequate image quality with the available physiologic accommodating force. The iterative mathematical modeling based upon the prototype yielded maximized optical and mechanical performance through maximum allowable gel thickness to extrusion diameter ratio, maximum feasible refractive index change at the interface, and minimum gel material properties in Poisson's ratio and Young's modulus. The design prototype performed well. It operated within the physiologic constraints of the human eye including the force available for full accommodative amplitude using the eye's natural focusing feedback, while maintaining image quality in the space available. The parameters that optimized optical and mechanical performance were delineated as those, which minimize both asphericity and actuation pressure. The design parameters outlined herein can be used as a template to maximize the performance of a deformable interface intraocular lens. The article combines a multidisciplinary basic science approach from biomechanics, optical science, and ophthalmology to optimize an intraocular lens design suitable for preliminary animal trials.

Lentes intraoculares multifocales de geometría fractal

This paper is a summary of the results of the PhD entitled: Design, Fabrication and Quality Control of the Multifocal Intraocular Lenses presented and defended by L. Remon at Universitat Politecnica de Valencia (October 2012) and supervised by Prof. J.A Monsoriu and Prof. W.D. Furlan [1]. Multifocal IOLs (MIOLs) are a promising alternative to presbyopic patients (suffering from cataracts). There exist several commercially available models and designs of MIOLs, each one with its own drawbacks and advantages, evidencing that the optimum MIOL has not yet designed. This work presents the design, and quality control of a new design of MIOL with a fractal profile. This type of lenses provides an extended depth of field and a reduced chromatic aberration compared to other commercially available designs. Additionally, to assess the optical quality of MIOLs, two different experimental setups were designed ad-hoc; according to the requirements of the UNE ISO 11979-2 standard.

Study of the force dynamics at the capsular interface related to ciliary body stimulation in a primate model.

To study the mechanical dynamics between the zonuli-capsular complex and an accommodating intraocular lens mechanics simulator using pharmacological stimulation of the ciliary body in a primate eye. Following phacoemulsification removal of the lens, force/movement gauges simulating the accommodating intraocular lens mechanics were implanted in 8 primate eyes (4 positioned in-the-bag and 4 on-the-bag). The gauge readings were taken under full effect of pilocarpine 4% or atropine 1% starting 6 weeks after surgery and following 3-month intervals for 30 months. An average movement of 390 µm for on-the-bag gauges and 145 µm for in-the-bag gauges was documented at 3 months postoperatively. The mechanical compliance of in-the-bag gauges rapidly deteriorated with capsular fibrosis developing inside the gauge and the capsular bag shrinking around it. On-the-bag gauges remained functional but the initial compliance was compromised over time by the pressure build up caused by the fibrotic capsular bag. Following phacoemulsification, capsular fibrosis causes disappearance of the mechanical forces detected by an in-the-bag gauge. An on-the-bag gauge detects active forces at the sulcus lasting at least 5 years, although the contracting capsule pressure compromises its compliance. These findings have important implications for future accommodating intraocular lens designs.

Improvement of Optics, Mechanics and the Usability of a Mechanical Eye Model for Vision Quality Evaluation of IOLs.

Cataract surgeries are one of the most frequent medical interventions with more than 11 million surgeries per year. During the surgery the clouded human lens is extracted and an artificial lens - the intraocular lens (IOL) - is implanted into the affected eye. Nowadays IOLs with different optical properties such as monofocal, bifocal or multifocal lenses are used for implantation. The postoperative lens position is influenced by healing processes resulting into shifts and tilts of the IOL that finally affect the refractive outcome. New IOL designs allow also the correction of high order aberrations and presbyopia. To fulfil the requirements of more sophisticated IOLs a closer investigation of the positioning sensitivity is necessary. A mechanical eye model was implemented for testing different types of IOLs under physiological conditions. New measurement setups are presented to get more detailed information about optical quality criteria such as the modulation transfer function (MTF), point spread function (PSF) and Strehl ratio. Additionally image quality is evaluated by the determination of the Zernike coefficients and the patients’ physiological impression of vision.

Attenuating Photostress and Glare Disability in Pseudophakic Patients through the Addition of a Short-Wave Absorbing Filter.

To evaluate the effects of filtering short wavelength light on visual performance under intense light conditions among pseudophakic patients previously implanted with a clear intraocular lens (IOL). This was a patient-masked, randomized crossover study conducted at 6 clinical sites in the United States between September 2013 and January 2014. One hundred fifty-four bilaterally pseudophakic patients were recruited. Photostress recovery time and glare disability thresholds were measured with clip-on blue-light-filtering and placebo (clear; no blue-light filtration) glasses worn over patients' habitual correction. Photostress recovery time was quantified as the time necessary to regain sight of a grating target after intense light exposure. Glare disability threshold was assessed as the intensity of a white-light annulus necessary to obscure a central target. The order of filter used and test eye were randomized across patients. Photostress recovery time and glare disability thresholds were significantly improved (both P < 0.0001) when patients used blue-light-filtering glasses compared with clear, nonfiltering glasses. Compared with a nonfiltering placebo, adding a clip-on blue-absorbing filter to the glasses of pseudophakic patients implanted with clear IOLs significantly increased their ability to cope with glare and to recover normal viewing after an intensive photostress. This result implies that IOL designs with blue-light-filtering characteristics may be beneficial under intense light conditions.

Treatment of Corneal Astigmatism at the Time of Cataract Surgery, What Can Be Promised

The treatment of corneal astigmatism at the time of cataract surgery is commonplace. Corneal incisional surgery and toric intraocular lenses (IOLs) are routinely utilised; the role of each modality is understood and defined. Although technological advances have been made in the assessment of the cornea and in the execution of the treatment options, recent innovations in toric IOL designs may be more significant for the comprehensive ophthalmologist.

Subjective complaints after cataract surgery: common causes and management strategies.

To describe the common causes of, and management strategies for, nonrefractive subjective visual complaints after cataract surgery. Over the past decade, clinical observations and ray-tracing models have greatly increased our understanding of positive and negative dysphotopsias after cataract surgery. The primary factor behind positive dysphotopsias is the use of high refractive index square-edge intraocular lenses (IOLs). Primary and secondary factors that underlie negative dysphotopsias are now better characterized, which has led to successful interventions including IOL exchange and Nd:YAG laser anterior capsulotomy. Positive and negative dysphotopsias occur after implantation of monofocal IOLs, and can rarely be disabling to patients. Visual complaints after multifocal IOL implantation are more common than after monofocal IOL implantation, but still rarely require significant intervention. A better understanding of the risk factors and optical causes of dysphotopsias will allow for IOL design and patient selection that maximize satisfaction after cataract surgery.

Optimisation of the visualisation technique for optical paths through intraocular lenses for characterisation of multifocal imaging properties of Fresnel-zone plates

The utilisation of the diffractive properties of Fresnel zone plates offers the possibility of intraocular lens designs with multiple foci. Such intraocular lenses can be manufactured by two-photon polymerisation (2PP). This paper explains the underlying concept and shows the principles for visualisation of the focus properties of such implants.