Accommodative Intraocular Lens Research Articles

Optimized multielement accommodative intraocular lens with a four-freeform-surface Alvarez lens and a separate aspheric lens.

This paper proposes an accommodative intraocular lens (IOL), which consists of a two-element Alvarez lens and an aspheric lens for changing focal power and refractive power, respectively. The four-freeform-surface Alvarez lens is optimized for a multiple field of view; further, the aspheric lens also corrects the aberrations induced by the corneal asphericity of the human eye over the whole range of accommodation. A simulation using optical design software demonstrates its excellent performance in that the values of the modulation transfer function at 100cycles/mm all reach ∼0.4 with a ±5° field of view for 3 and 5mm pupils.

Design and ex situ performance of a shape-changing accommodating intraocular lens

Presbyopia, the age-related loss of the crystalline lens’s ability to dynamically focus, occurs primarily because of stiffening of lens material, making the ciliary muscle forces insufficient to reshape the lens. Despite its prevalence, there is no satisfactory solution to presbyopia. Here we present a novel accommodating intraocular lens (AIOL) able to reshape upon equatorial forces in compliance with the eye’s accommodating mechanism. The concept and design parameters are demonstrated through finite element model simulations and measurements in a manufactured AIOL prototype, using custom quantitative 3D OCT (geometrical changes) and laser ray tracing (power changes), with forces radially applied using a custom eight-arm mechanical stretcher. There was an excellent agreement between simulations and measurements (1% for the focal length and 11.4% for geometrical parameters, on average) for radial load up to 0.6 N. The developed design is expected to achieve ∼2.5D of effective power change with a polymer material with 0.10–0.25 MPa Young’s modulus and n=1.43−1.46.

An accommodative intraocular lens study and experiment, based on compliant mechanisms

To replace the human lens with a cataract, a novel haptic-type lens based on compliant mechanisms is proposed to provide both radial and axial input displacement to change the shape and the axial movement of the optical lens, respectively. With this method, the optical power of an intraocular lens (IOL) can be remarkably improved, thereby enhancing the visual acuity of patients. In terms of the optical power of an IOL obtained by the clinical study, the maximum level is around 3.50 Diopters (D), 3 months later. However, the minimum requirement of the normal physiological function is around 8.00 D. In this study, the haptic is connected to an optical-grade silicon wafer made of polydimethylsiloxane, establishing a human optical system with an optical power of approximately 23.02 D.

Intraocular lens correction of presbyopia.

The continued development of intraocular lens (IOL) technology has led to a dramatic improvement in refractive outcomes. New and innovative ways of achieving the desired postoperative refractive goals continue to be developed. This article aims to review the currently available IOL modalities for correction of presbyopia at the time of cataract surgery, including reference to high-quality comparative studies, where available, and discussion of strengths as well as limitations of the currently available IOL technologies. It has been shown that multifocal compared to monofocal IOL was associated with higher rates of spectacle independence, but higher rates and severity of symptomatic glare as well as reduced contrast sensitivity. Within multifocal IOLs, diffractive compared to refractive IOLs tended to have better near vision and a lower rate of symptomatic glare. Extended depth-of-focus IOLs compared to diffractive multifocal IOL demonstrated equal or superior intermediate visual acuity, with less than or equal rates of glare. Accommodative IOLs represent a broad range of technologies that continue to develop, and new technologies offering opportunities for postoperative adjustment of refractive outcome are emerging.

Intraocular Photobonding to Enable Accommodating Intraocular Lens Function.

PurposeAccommodating intraocular lenses (A-IOLs) require capturing the ciliary muscle forces. Prior work demonstrated strong photo-initiated bonding between strips of capsular bag and poly(2-hydroxyethyl methacrylate); (pHEMA) polymer in an extraocular setting. We demonstrate that photobonding can be achieved intraocularly.MethodsPhacoemulsification was performed in porcine eyes (<24 hours postmortem). A commercial intraocular lens (IOL; pHEMA-MMA material) was inserted in the capsular bag. Surface contact between the lens and capsular bag was ensured by continuous air infusion into the anterior chamber of the eye, which provided sufficient pressure at the interface, as well as oxygen. The capsular bag and IOL then were stained with 0.1% photosensitizer Rose Bengal (RB) solution. A fiberoptic probe connected to a diode-laser (532 nm) was used to locally irradiate the capsular bag–IOL interface intraocularly. The bonding breaking load was evaluated in a uniaxial stretcher.ResultsPhotobonding occurred in the 0.8 to 1.6 W/cm2 irradiance range and 2.5 to 7 minutes irradiation time. Average forces of 0.12 N stretched but did not break the bond. These forces, applied uniaxially, are higher than the summed net accommodating force of the ciliary muscle along the entire equator (0.08 N). In two cases, the zonulae broke before the bonded region.ConclusionsPhotobonding between the capsular bag and IOL polymer can be achieved intraocularly, in a procedure compatible with standard cataract surgery. This technique will enable the mechanisms of A-IOLs not to rely on capsular bag integrity or natural haptic fibrosis.Translational RelevanceIntraocular photobonding holds promise to enable operation of A-IOLs to restore accommodation in presbyopia, affecting 100% of the population >45 years old. Intraocular bonding of polymer material to ocular tissue also may find other applications in ophthalmology.

The efficacy of accommodative versus monofocal intraocular lenses for cataract patients: A systematic review and meta-analysis.

We performed a systematic review and meta-analysis to evaluate whether accommodative intraocular lenses (AC-IOLs) are superior for cataract patients compared with monofocal IOLs (MF-IOLs). Pubmed, Embase, Cochrane library, CNKI, and Wanfang databases were searched through in August 2018 for AC-IOLs versus MF-IOLs in cataract patients. Studies were pooled under either fixed-effects model or random-effects model to calculate the relative risk (RR), weighted mean difference (WMD), or standard mean difference (SMD) and their corresponding 95% confidence interval (CI). Distance-corrected near visual acuity (DCNVA) was chosen as the primary outcome. The secondary outcomes were corrected distant visual acuity (CDVA), pilocarpine-induced IOL shift, contrast sensitivity, and spectacle independence. Seventeen studies, involving a total of 1764 eyes, were included. Our results revealed that AC-IOLs improved DCNVA (SMD = -1.84, 95% CI = -2.56 to -1.11) and were associated with significantly greater anterior lens shift than MF-IOLs (WMD = -0.30, 95% CI = -0.37 to -0.23). Furthermore, spectacle independence was significantly better with AC-IOLs than with MF-IOLs (RR = 3.07, 95% CI = 1.06-8.89). However, there was no significant difference in CDVA and contrast sensitivity between the 2 groups. Our study confirmed that AC-IOLs can provide cataract patients with DCNVA and result in more high levels of spectacle independence than MF-IOLs. Further studies with larger data set and well-designed models are required to validate our findings.

Clinical application of accommodating intraocular lens.

The present review describes recent advances in application of accommodating intraocular lenses (AIOLs). Standard monofocal intraocular lenses (MIOLs) only correct distance vision, while AIOLs are designed to allow both good distance vision and near vision, which is achieved through the contraction and relaxation of ciliary muscles by providing transformation of the axial movement or curvature of the lens. Thus, AIOLs may be a better choice for those patients who demand a higher level of visual performance. Since techniques to analyze the performance of AIOLs have not been standardized, and there is a variety of both subjective and objective methods, it is hard to measure the performance of these intraocular lenses. By evaluating advantages and disadvantages of various AIOLs, and introducing techniques for measurement the performance postoperative, this paper can provide some relative information on choosing the type of AIOLs in the clinic.

Clinical Outcomes of Tetraflex Accommodative Intraocular Lens Implantation 2 Years after Cataract Surgery for Presbyopia

Clinical Outcomes of Tetraflex Accommodative Intraocular Lens Implantation 2 Years after Cataract Surgery for Presbyopia

Erratum for "Analysis of Accommodative Performance of a New Accommodative Intraocular Lens".

Erratum for "Analysis of Accommodative Performance of a New Accommodative Intraocular Lens".

Biomechanical investigations on accommodation of the eye

The biomechanics of accommodation are of particular interest in terms of the causes of presbyopia and the function of intraocular lenses. The aim of the present article is to model the mechanism of accommodation in detail. The state of the art of applying biomechanical models to accommodation is presented, which enables the accommodation process to be understood. The established models, which are based on the Helmholtz theory, can explain the accommodation process in aplausible manner. These models thereby also enable further investigations on the genesis of presbyopia as well as on the development of accommodative intraocular lenses and implants. However, measurements are always necessary to compare the simulation results with reality, and to provide input and material data as well as geometric dimensions of components of the eye.

Prospective analysis of outcomes of cataract phacoemulsification with the implantation of the Crystalens accommodative intraocular lens.

Objectives: To evaluate visual outcomes after bilateral implantation of Crystalens accommodative intraocular lenses. Material and methods: The study group consisted of 20 patients (40 eyes) who underwent uneventful phacoemulsification through a 2.8 mm wide clear corneal incision followed by the implantation of an accommodative intraocular lens Crystalens HD or Crystalens AO. Uncorrected visual acuity, best corrected visual acuity, distance corrected intermediate visual acuity, distance corrected near visual acuity, best near visual acuity 1, 3, 6, 12 months postoperatively were evaluated. Distance visual acuity was measured with Snellen test. Near (40 cm) and intermediate (80 cm) visual acuity were measured with Jeager test. Results: The mean uncorrected distance visual acuity was 0.94 and 0.89 at month 1. and 12., respectively. The distance corrected intermediate visual acuity was 0.9 and 0.86 at month 1. and 12., respectively. The distance corrected near visual acuity was J1 in 10% and J3 in 50% of patients at month 1. It was J1 in 10% and J3 in 55% of patients at month 12. Conclusions: Crystalens intraocular lens implantation in our patients enabled them to achieve good distance, near and intermediate visual acuity. The majority of patients did not require spectacle correction for distance and near (87.5% and 65%, respectively). The achieved results did not differ significantly at months 1., 6., and 12. postoperatively.

Accommodative Intraocular Lenses

Research in Medical & Engineering Sciences Accommodative Intraocular Lenses Felipe Soria* and Caterina Senn Universidad Advenista del Plata, Argentina *Corresponding author: Felipe Soria, Universidad Advenista del Plata, 25 de Mayo 99, E3103XAF Libertador San Martín, Entre Ríos, Argentina Submission: August 08, 2017; Published: September 06, 2017 DOI: 10.31031/RMES.2017.01.000511 ISSN : 2576-8816Volume1 Issue3

Optical aberrations, accommodation, and visual acuity with a bioanalogic continuous focus intraocular lens after cataract surgery

PurposeTo evaluate the visual outcomes, pseudoaccommodation, and wavefront aberrometry after implantation of Wichterle IOL-Continuous Focus (WIOL-CF®, Gelmed International, Kamenne Zehrovice, Czech Republic) by i-Trace aberrometry. MethodsIn this retrospective interventional case series study, after cataract surgery with implantation of accommodative WIOL-CF®, the patients were evaluated with i-Trace aberrometer for measurement of modulation transfer function (MTF), point spread function (PSF), total aberrations, higher order aberrations (HOAs) at far and near and pseudoaccommodation. The pre and postoperative visual acuity at near and distance were also measured. ResultsForty eyes of 20 patients (aged 40–77 years) were enrolled in this study with mean follow-up time of up 13.10 ± 5.52 months. The mean logMAR corrected distance visual acuity (CDVA) improved from 0.20 ± 0.14 preoperatively to 0.10 ± 0.09 at the last follow-up after surgery (P = 0.002). The results were 60% J1, 70% J2, 85% J3, 90% J4, 95% J5 and 100% for J6. The mean pseudoaccommodation, range of accommodation volume, and average of peak accommodation were −2.52 ± 1.56 diopters (D), 1.50 to 5.25 D and −3.25 ± 1.25 D, respectively. The mean MTF at 5 cycles per degree at far was 0.200 ± 0.10 and for near was 0.207 ± 0.10. PSF at far and near was 0.0002 and 0.001, respectively. The mean root mean square (RMS) value of HOAs; total, coma spherical aberration, trefoil, and secondary astigmatism were 1.08 ± 0.48 μm, 0.89 ± 0.45 μm, −0.33 ± 0.23 μm, 0.25 ± 0.17 μm, and 0.15 ± 0.13 μm for far and 0.88 ± 0.49 μm, 0.73 ± 0.46 μm, −0.25 ± 0.22 μm, 0.19 ± 0.16 μm and 0.11 ± 0.10 μm for near, respectively. There was a decrease in HOAs at near relative to far (P < 0.05). ConclusionWIOL-CF® seems to be an acceptable accommodative intraocular lens (IOL) in terms of uncorrected near and distant visual outcomes, MTF and HOA.

Anterior Segment Biometry of the Accommodating Intraocular Lens and its Relationship With the Amplitude of Accommodation.

To evaluate the anterior segment biometry of the Tetraflex accommodating intraocular lens (AIOL) and the contribution of forward movement to the amplitude of accommodation (AMP). Patients who underwent phacoemulsification with implantation of Tetraflex AIOLs and control nonaccommodating intraocular lenses were imaged by custom-built, long scan depth spectral-domain optical coherence tomography at relaxed and maximal accommodative states. Anterior segment biometry was performed and correlated with the clinical manifestation including AMP. Patients in the Tetraflex group showed better distance-corrected near visual acuity (logMAR 0.43±0.10 vs. logMAR 0.51±0.10, P<0.05) and greater AMP (1.99±0.58 diopters [D] vs. 1.59±0.45 D, P<0.05) compared with the control group. The measurement of the postoperative anterior chamber depth (ACD) during accommodation showed a forward movement of the AIOLs in 16 eyes (69.6%). Compared with the control group, a greater proportion of cases in the Tetraflex group experienced forward movement (χ test, P<0.001). The AMP in the AIOL group negatively correlated with changes in postoperative ACD during accommodation (r=-0.47, P<0.05), whereas AMP in the control group negatively correlated with postoperative pupil diameter (r=-0.57, P<0.05). The Tetraflex AIOLs seemed to have a tendency for forward movement; however, the slight forward axial shifts of the Tetraflex AIOL during natural accommodation may not produce a clinically relevant change in optical power.

Comparison of visual outcomes, spectacles dependence and patient satisfaction of multifocal and accommodative intraocular lenses: innovative perspectives for maximal refractive-oriented cataract surgery

BackgroundThe aim of this study was to evaluate visual outcomes for different working distances (far, 60 cm and 33 cm) and impact on vision quality of multifocal IOLs AcrySof ResTOR SN6AD1 and SN6AD3 (Alcon, Inc., Fort Worth, Texas, USA) as well as REVIEW FIL611PV multifocal and OPTOFLEX FIL618 accommodative IOLs (Soleko, Ltd., Rome, Italy) in patients undergoing bilateral phacoemulsification.MethodsIn this observational prospective study 63 patients undergoing binocular cataract surgery were divided into four groups for implantation of one of the IOLs under evaluation. Visual outcomes were evaluated at 1 day, 7 days, 1 month, 3 months and 6 months after surgery. Patients’ satisfaction and spectacle independence were evaluated with questionnaires administered at the 6-months follow-up.ResultsImprovements in visual acuity for the three working distances were statistically significant in all cases compared to the preoperative status, especially after binocular implantation. The AcrySof ReSTOR SN6AD1 multifocal IOL provided the best visual acuity results and tolerability for all working distances. While performing worse than SN6AD1, FIL611PV and FIL618 provided better uncorrected visual acuity and spectacles independence for intermediate/close-up and far distances respectively, in comparison with the SN6AD3 group.ConclusionsSN6AD1 was confirmed the best choice for all working distances. However, FIL611PV IOL may represent a valid and more cost-effective alternative, especially if surgeons intend to prioritize spectacle independence and patient autonomy at intermediate and close-up distances, in accordance to specific needs and requests.Trial registrationTrial retrospectively registered in ISRCTN Registry on 02/02/2017. TRN: ISRCTN14145737.

Review of Static Approaches to Surgical Correction of Presbyopia.

Presbyopia is the primary cause of reduction in the quality of life of people in their 40s, due to dependence on spectacles. Therefore, presbyopia correction has become an evolving and rapidly progressive field in refractive surgery. There are two primary options for presbyopia correction: the dynamic approach uses the residual accommodative capacity of the eye, and the static approach attempts to enhance the depth of focus of the optical system. The dynamic approach attempts to reverse suspected pathophysiologic changes. Dynamic approaches such as accommodative intraocular lenses (IOLs), scleral expansion techniques, refilling, and photodisruption of the crystalline lens have attracted less clinical interest due to inconsistent results and the complexity of the techniques. We have reviewed the most popular static techniques in presbyopia surgery, including multifocal IOLs, PresbyLASIK, and corneal inlays, but we should emphasize that these techniques are very different from the physiologic status of an untouched eye. A systematic PubMed search for the keywords “presbylasik”, “multifocal IOL”, and “presbyopic corneal inlay” revealed 634 articles; 124 were controlled clinical trials, 95 were published in the previous 10 years, and 78 were English with available full text. We reviewed the abstracts and rejected the unrelated articles; other references were included as needed. This narrative review compares different treatments according to available information on the optical basis of each treatment modality, including the clinical outcomes such as near, intermediate, and far visual acuity, spectacles independence, quality of vision, and dysphotopic phenomena.

Accommodative IOLs: an update on recent developments

SummaryPurposeTo compare the clinical results of the Lumina accommodative intraocular lens (IOL) with a standard monofocal IOL.MethodsClinical study including 86 eyes that underwent cataract surgery. The study group included 61 eyes implanted with the Lumina. The control group included 25 eyes implanted with an Acrysof monofocal IOL. Visual function, contrast sensitivity (CS) and accommodation with an open‐field autorefractor were measured during 1 year.ResultsUncorrected near visual acuity (UNVA) was 0.07 ± 0.08 LogRAD for the Lumina group and 0.37 ± 0.19 in control group (p &lt; 0.01); corrected distance near visual acuity (CDNVA) was 0.11 ± 0.12 for the Lumina group and 0.41 ± 0.15 for the control group (p &lt; 0.01). Defocus curves showed significant better results for the Lumina group for defocus ranging from −4.50 to −0.50D (p &lt; 0.01). Accommodation was 0.63 ± 0.41, 0.91 ± 0.51 and 1.27 ± 0.76D for the Lumina group and 0.10 ± 0.15, 0.06 ± and 0.07 ± 0.10D for the control group at accommodation stimuli of 2.0, 3.0 and 4.0D, respectively. CS was the same for both groups (p ≥ 0.26).ConclusionsThe Lumina accommodative IOL effectively restores the visual function and accommodation after cataract surgery with no influence on the postoperative CS.

A stepwise approach for the management of capsular contraction syndrome in hinge-based accommodative intraocular lenses.

PurposeThe aims of this study are to define the various stages of capsular contraction syndrome (CCS) and its effect on refractive error with hinge-based accommodating intraocular lenses (IOLs) and to describe a systematic approach for the management of the different stages of CCS.MethodsHinge-based accommodative IOLs function via flexible hinges that vault the optic forward during accommodation. However, it is the flexibility of the IOL that makes it prone to deformation in the event of CCS. The signs of CCS are identified and described as posterior capsular striae, fibrotic bands across the anterior or posterior capsule, and capsule opacification. Various degrees of CCS may affect hinge-based accommodating IOLs in a spectrum from subtle changes in IOL appearance to significant increases in refractive error and loss of uncorrected visual acuity. The signs of CCS and its effect on IOL position and the resulting changes in refractive error are matched to appropriate treatment plans.ResultsA surgeon can avoid CCS and manage the condition if familiar with the early signs of CCS. If CCS is identified, yttrium–aluminum–garnet laser capsulotomy should be considered. If moderate CCS occurs, it may be effectively treated with insertion of a capsular tension ring. If CCS is allowed to progress to advanced stages, an IOL exchange may be necessary.ConclusionSurgeons should be familiar with the stages of CCS and subsequent interventions. The steps outlined in this article help to guide surgeons in the prevention and management of CCS with hinge-based accommodative IOLs in order to provide improved refractive outcomes for patients.

Hybrid MEMS-SMA structure for intraocular lenses

This paper presents the design, fabrication and evaluation of a novel ring-shape MEMS micro actuator for a latching mechanism for low power consumption and large displacement linear actuation, which can be applicable for a variable-focus lens system such as an accommodative intraocular lens (AIOL). The proposed actuator consists of a shape-memory-alloy (SMA) ring, parylene spring and shoes. The parylene spring was carefully designed for independent control of radial and axial stiffness, which can be realized by a high aspect ratio cross section and a meander structure. The maximum force generated by the parylene spring was about 50mN. Two types of SMA actuator have been examined for the actuation: simple wire and micro spring types. The SMA in wire shape was evaluated in two configurations. Maximum displacement as high as 300μm was obtained by using the SMA micro spring.

Visual Outcomes and Accommodative Response of the Lumina Accommodative Intraocular Lens

To compare visual acuity, accommodation, and contrast sensitivity of the AkkoLens Lumina accommodative intraocular lens (AkkoLens Clinical b.v., Breda, The Netherlands) with a standard monofocal intraocular lens (IOL). Randomized clinical trial. The study enrolled 86 eyes with cataract that all required cataract surgery and IOL implantation. The study group included 61 eyes that were implanted with the Lumina. The control group included 25 eyes that were implanted with an Acrysof SA60AT (Alcon, Fort Worth, TX, USA) monofocal IOL. The distance and near visual acuities, contrast sensitivity, and accommodation were measured over a 1-year follow-up period. Accommodation was measured subjectively, using defocus curves, and objectively, with an open-field autorefractor. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities did not differ significantly between the groups (P ≥ .21) over the 12months. However, the uncorrected near visual acuity (UNVA) was 0.07 ± 0.08 logRAD for the Lumina group and 0.37 ± 0.19 logRAD for the control group (P < .01) and the corrected distance near visual acuity (CDNVA) was 0.11 ± 0.12 LogRAD for the Lumina group and 0.41 ± 0.15 LogRAD for the control group (P < .01). Defocus curves showed a statistically significant difference between groups for defocus ranging from-4.50 to-0.50 diopters (D) (P< .01) with significantly higher visual acuities for the Lumina group. Subjective accommodation, as determined from defocus curves, was 3.05 ± 1.06, 3.87 ±1.27, and 5.59 ± 1.02 D for the Lumina group and 1.46 ± 0.54, 2.00 ± 0.52, and 3.67 ± 0.75 D for the control group at visual acuities of 0.10, 0.20, and 0.4 logMAR for both groups, respectively. The objective accommodation, measured by an open-field autorefractor, was 0.63 ± 0.41, 0.69 ± 0.45, 0.91 ± 0.51, and 1.27 ± 0.76 D for the Lumina group and 0.10 ± 0.15, 0.12 ±0.15, -0.06 ± 0.09 and 0.07± 0.10 D for the control group at accommodation stimuli of 2.0, 2.5, 3.0, and 4.0 D, respectively. Contrast sensitivity was the same for both groups (P ≥ .26). The Lumina accommodative IOL effectively restores the visual function, accommodation, and contrast sensitivity after cataract surgery with no influence on the postoperative contrast sensitivity.