Double-C loop platform in combination with hydrophobic and hydrophilic acrylic intraocular lens materials

Clinical Outcomes of a Monofocal, Optimized, Aspheric, Hydrophobic Acrylic Intraocular Lens Implant

Purpose

To evaluate the refractive and visual outcomes of eyes implanted with monofocal, optimized, aspheric, hydrophobic acrylic intraocular lenses (IOL) following cataract surgery.

Methods

The study assessed 55 eyes implanted with CT LUCIA® 621P IOLs (Carl Zeiss Meditec AG, Jena, Germany) at 3-months postsurgery. The main outcome measures were refractive error, monocular corrected distance visual acuity (CDVA), monocular uncorrected distance visual acuity (UDVA), photopic and mesopic contrast sensitivity, and wavefront aberrations. Patients were asked to complete the Catquest-9SF questionnaire.

Results

At 3 months, the cumulative Snellen visual acuity was 20/20 in 94.55% of eyes and 20/25 or better in 100%. The difference between the UDVA and CDVA was either the same (70.91%) or better (29.09%) in all eyes. The mean Snellen decimal UDVA and DCVA were 1.07 ± 0.15 and 1.13 ± 0.11, respectively. The safety and efficacy indexes were 1.48 and 1.40, respectively. 47.27% of eyes showed a spherical equivalent ±0.13 D, with 92.73% of the eyes were within ±0.50 D and all eyes were within ±1.00 D. The mean spherical equivalent was -0.03 ± 0.30 D and the mean refractive cylinder -0.36 ± 0.34 D. The log photopic and mesopic contrast sensitivity functions were good and similar for all spatial frequencies. All patients reported being either fairly satisfied (score 3) or very satisfied (score 4) with their vision (mean = 3.64 ± 0.49). No intra- and postoperative complications were reported during the 3 months of follow-up.

Conclusion

The current study demonstrates that excellent visual and refractive outcomes, as well as patient satisfaction, can be achieved after cataract surgery with optimized, aspheric CT LUCIA 621P monofocal IOLs.

Visual and Refractive Outcomes After Bilateral Implantation of a Biconvex Aspheric Toric Monofocal Intraocular with a Double C-Loop Haptic Design

Purpose

To show the visual and refractive outcomes in cataract patients with corneal astigmatism when bilaterally implanted with a biconvex aspheric toric monofocal intraocular lens (IOL) with a double C-loop haptic-design.

Methods

Forty-seven cataract patients (94 eyes) with corneal astigmatism (≥0.75D) were implanted with the monofocal PODEYE toric IOL and assessed for 4-6 months post-surgery. Measurements included monocular and binocular uncorrected-distance visual acuity (UDVA) and corrected-distance visual acuity (CDVA), under both photopic and mesopic lighting conditions. Refraction, photopic and mesopic contrast sensitivity (with and without glare), and rotational stability were also recorded at the last postoperative visit.

Results

At 4-6 months, 78.2% and 98.9% of eyes were within ±0.50D and ±1.00D of the target refraction, respectively. The mean spherical equivalent and refractive cylinder values were 0.09±0.35D and -0.36±0.35D, respectively. 76.5% and 98.8% of eyes presented a postoperative refractive cylinder of ≤0.50D and ≤1.00D, respectively. 91.5% and 100% of patients had a binocular UDVA and CDVA of ≥20/25, respectively. The mean binocular UDVA and CDVA were 0.02±0.08 and -0.02±0.07 logMAR, respectively. Under mesopic conditions, 78.7% and 83.0% of patients presented a binocular UDVA and CDVA ≥20/32, respectively. The mean binocular UDVA and CDVA were 0.15±0.11 and 0.12±0.11 logMAR, respectively. The patients showed good contrast sensitivity under photopic and mesopic conditions. The mean absolute IOL rotation was 1.22±2.21 degrees with 97.87% of eyes having a rotation of <10 degrees.

Conclusion

This study shows good visual and refractive outcomes for the PODEYE toric IOL when implanted bilaterally in cataract patients with corneal astigmatism.

Evaluation of the mechanical stability of intraocular lenses using digital image correlation

This study aimed to evaluate the mechanical stability of seven different intraocular lens (IOL) haptic designs by using digital image correlation to measure their mechanical biomarkers (axial displacement, tilt, and rotation) under quasi-static compression. The IOLs were compressed between two clamps from 11.00 up to 9.50 mm whilst a 3D deformation dataset was acquired every 0.04 mm. Results revealed that flexible and mixed IOL designs exhibited better mechanical response for smaller compression diameters compared to stiff designs. Conversely, stiff designs performed better for larger compression diameters. These findings may aid in the selection and development of more mechanically stable IOL designs.

Rotational stability and clinical outcomes after implantation of a new monofocal toric intraocular lens with double C-loop design

PURPOSE

To investigate rotational stability and visual outcomes of patients unilaterally or bilaterally implanted with a new monofocal toric intraocular lens (IOL).

SETTING

Ophthalmology service, clinique Beausoleil, avenue de Lodève, Montpellier.

DESIGN

Single-center retrospective study.

METHODS

This study included patients who underwent routine cataract surgery with the PODEYE toric (BVI/PhysIOL SA, Liège, Belgium) IOL using the ZEISS CALLISTO eye®. Biometry and keratometry data, refractive outcomes, rotational stability, and astigmatism correction were recorded. IOL rotation was evaluated using an image analysis technique. Postoperative assessments were performed at 1 week, 1 month, and 4 to 6 months after surgery.

RESULTS

Clinical outcomes of 102 patients (136 eyes) were analyzed. Patients had a mean age of 74 years. Of the included eyes, 25% had an axial length greater than 24.5mm. Median postoperative IOL rotation from baseline (surgery) was 2̊. With the exception of one outlier (15̊ rotation), IOL rotation was ≤ 6̊ (1 month) and ≤ 10̊ (4-6 months) in 100% of the eyes. No surgical IOL re-positioning was required. Median postoperative corrected distance visual acuity was -0.08 logMAR, and median postoperative subjective cylinder was between 0.25 and 0.50 D.

CONCLUSION

The PODEYE toric IOL showed high rotational stability, allowing for correction of corneal astigmatism during cataract surgery.

Clinical Performance of a Hydrophobic Acrylic Diffractive Trifocal Intraocular Lens in a Japanese Population

INTRODUCTION

In this study, clinical performance of a hydrophobic acrylic diffractive trifocal intraocular lens (IOL) with double C-loop haptics was evaluated in Japanese cataract eyes.

METHODS

Twenty-three patients had bilateral cataract surgery with the implantation of a trifocal IOL with double C-loop haptics. Postoperative examinations at 6 months included assessing uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA) at 5 m, uncorrected intermediate visual acuity (UIVA), distance-corrected intermediate visual acuity (DCIVA) at 80 cm, uncorrected near visual acuity (UNVA) and distance-corrected near visual acuity (DCNVA) at 40 cm. Binocular defocus, contrast sensitivity, spectacle independence, symptoms of photic phenomena and quality of vision (QOV) were also observed.

RESULTS

Twenty-three patients received 46 IOLs binocularly. Manifest refraction spherical equivalent was - 0.227 ± 0.385 D (mean ± standard deviation) at 6 months postoperatively. Binocular UDVA, binocular UIVA and binocular UNVA were - 0.101 ± 0.065, - 0.021 ± 0.079 and 0.022 ± 0.095 logMAR units, respectively. Binocular CDVA, binocular DCIVA and binocular DCNVA were - 0.151 ± 0.044, - 0.042 ± 0.067 and - 0.011 ± 0.080 logMAR, respectively. Binocular CDVA of 0.00 logMAR or better was obtained in the defocus from - 3.0 D until + 0.5 D. Only 8.7% of patients required the use of spectacles postoperatively. There were no symptoms of glare, halo and light disturbance in 78.3%, 56.5% and 69.6% of patients, respectively. QOV scores significantly improved postoperatively (P < 0.0001).

CONCLUSION

The hydrophobic acrylic trifocal IOL with double C-loop haptics provides good visual performance at all distances and produces high spectacle independence rate and patient satisfaction.

TRIAL REGISTRATION NUMBER

NCT04699266 (Clinicaltrials.gov).

An Experimental Laboratory Study Using the Miyake-Apple Posterior View Technique to Investigate the Dynamics Between Capsular Bags and Different IOL Models

PURPOSE

To evaluate the dynamics between capsular bags and different intraocular lens (IOL) models in human cadaver eyes using the Miyake-Apple posterior view technique.

METHODS

In an in vitro laboratory study, human cadaver eyes were prepared according to the Miyake-Apple posterior view technique. Five IOLs from each of the six groups (Avansee 1P [Simonvision], Avansee 3P [Simonvision], CT Lucia [Carl Zeiss Meditec], Acrysof [Alcon Laboratories, Inc], RayOne [Rayner], and CT Asphina [Carl Zeiss Meditec]) were implanted into capsular bags with different diameters. The empty capsular bag diameter and capsular bag diameter with an IOL in it were evaluated based on the Miyake-Apple view pictures. Posterior capsule striae were observed and compared between groups. The arc of contact between IOLs and the capsular equator was noted. Correlations between the empty capsular bag diameter and the capsular bag diameter with IOL, as well as between the empty capsular bag diameter and the arc of contact, were examined. With the Avansee 3P as a reference, the area deviation of the haptics of IOL models with looped haptics was compared.

RESULTS

The capsular bag diameter with IOL inside and the arc of contact were proportional to the empty capsular bag diameter. The RayOne, Avansee 3P, and CT Lucia showed a longer arc of contact. Posterior capsule striae were observed in the Avansee 1P (1, 20%), Avansee 3P (5, 100%), Acrysof (1, 20%), and RayOne (2, 40%). Areas of deviation were 0.38 mm² (Avansee 1P), 0.24 mm² (CT Lucia), 0.34 mm² (Acrysof), and 0.31 mm² (RayOne), respectively.

CONCLUSIONS

Different IOL models showed varied characteristics in terms of capsular bag fitting and arc of contact. Understanding these dynamics is critical to optimizing postoperative outcomes. [J Refract Surg. 2022;38(10):654-660.].

The effects of premium intraocular lenses on presbyopia treatments

Background

Presbyopia has become a global disease affecting the world's aging population. Among various treatments, cataract extraction and intraocular lens (IOL) implantation have become the most popular and common methods of presbyopia correction. During the twentieth century, IOLs have underwent significant innovation and advancements to meet the patients' high demands for functional vision at all distances.

Main Text

To meet the increasing needs for excellent near and intermediate vision for daily activities, some premium IOLs with more than one focus have been developed, for example, the refractive MfIOLs, diffractive MfIOLs, extended depth of field (EDOF) IOLs, and accommodating IOLs (AIOLs) were introduced to meet this need. In addition, the add-on MfIOLs have been explored as promising supplementary IOLs for pseudophakic presbyopia. When selecting the MfIOLs, the IOLs' features, patients' characteristics, preoperative eye conditions, and treatment expectations should be considered.

Conclusions

In this review, we focus on the multifocal IOLs (MfIOLs) commonly used for presbyopia correction and systematically summarized their optical designs and clinical outcomes. More evidence-based studies are required to provide guidelines for MfIOL selection, provide maximum visual benefits, and develop personalized visual solutions in the future.

Geometry of Acrylic, Hydrophobic IOLs and Changes in Haptic-Capsular Bag Relationship According to Compression and Different Well Diameters: A Bench Study Using Computed Tomography

Introduction

Characteristics of the haptics and optic–haptic junction (OHJ) of an intraocular lens (IOL) affect IOL position in the capsular bag, positional stability, and the development of posterior capsule opacification. Therefore, the haptics and OHJ have a role in determining initial and long-term visual outcomes after cataract surgery. Understanding differences in the haptics and OHJ of available IOLs and in the relationships between the haptics of each IOL and the capsular bag across a range of capsular bag sizes might inform selection of an IOL model for individuals.

Purpose

To evaluate the geometry of five currently marketed, commonly used one-piece hydrophobic acrylic monofocal IOLs and changes in haptic–capsular bag relationships according to capsular bag size using a range of compression well diameters.

Methods

AcrySof SN60WF, CT LUCIA 621PY, enVista MX60, TECNIS ZCB00, and Vivinex XY1 IOLs were scanned with computed tomography (CT) in a dry, uncompressed state for quantitative analyses of haptic and OHJ dimensions and qualitative assessment of geometry. CT scanning was done after IOL placement into a series of compression wells (11.5, 11.0, 10.0, and 9.0 mm) for analyses of haptic angle of contact (AoC) and capsular bag contact (CBC). IOL axial alignment and haptic–capsular bag relationships were assessed on side-view and 3-dimensional top-view images, respectively.

Results

The qualitative and quantitative evaluations highlighted differences in haptic and OHJ geometry and dimensions across the five IOLs. All haptic dimensions (length, thickness, surface area, volume) and all OHJ dimensions (surface area and volume) were greatest for the CT LUCIA 621PY IOL. Compared to the IOL that had the smallest measurement for each parameter, the value for the CT LUCIA 621PY IOL was 31–91% larger. The lens with the largest OHJ surface area and volume showed values that were 500% and 240% greater than the corresponding values for the lens with the smallest OHJ surface area and OHJ volume. The AoC and CBC values decreased with increasing well size for all IOLs. The CT LUCIA 621PY had the greatest AoC and CBC values for all well sizes and the smallest percentage change in AoC and CBC comparing the values from the 9.0 mm and 11.5 mm wells.

Conclusion

The in vitro evaluations in this study highlight differences in the haptic and OHJ geometric characteristics of the five IOLs studied. The collected evidence refutes opinions that all hydrophobic acrylic one-piece IOLs are the same and supports the idea that individual IOLs can have relative advantages and disadvantages that depend on the individual case. We believe the knowledge of geometry is necessary for the surgeon to have the opportunity to select the best “customized” option in the individual case as a result of anatomical conditions and secondary diagnoses. Our bench study shows how big the differences are in currently available monofocal hydrophobic acrylic lenses.

Influence of anterior capsulorhexis shape, centration, size, and location on intraocular lens position: finite element model

PURPOSE

To evaluate the influence of anterior capsulorhexis shape, dimension, and eccentricity on intraocular lens (IOL) position.

SETTING

Laboratory investigation.

DESIGN

Computational model.

METHODS

A finite element model of the human crystalline lens capsule and zonule was created and the anterior capsule opened to simulate centered and decentered circular and elliptic rhexis. The model calculated capsular bag stress, IOL rotation, tilt, decentration, and vaulting, related to both capsular landmarks (absolute) and a reference IOL position defined as that obtained with a 5.0 mm circular and centered rhexis.

RESULTS

Mean von Mises stress along the IOL major z-axis was significantly higher than that along the perpendicular x-axis in all cases (P < .001), both at the equator and at the rhexis edge. Stress at the equator was always greater than that at the rhexis edge (P < .001) regardless of the rhexis shape and position. As rhexis eccentricity increased, the stress difference between the z- and x-axes increased. Absolute IOL tilt (range 10-1 to 10-7 degrees), decentration (10-3 to 10-7 mm), rotation (10-2 to 10-3 degrees), and vaulting (10-1 mm) were negligible from an optical standpoint, but all of them were significantly greater for decentered rhexis (both round and elliptic) compared with centered (P < .05).

CONCLUSIONS

Anterior capsulorhexis irregularity and/or eccentricity increase IOL tilt, decentration, rotation, and vaulting in a numerically significant but optically negligible way. Von Mises stress is much greater at the capsular bag equator compared with the rhexis edge and highly asymmetrically distributed in all cases. Stress asymmetry may influence postoperative biologic processes of capsular bag shrinking and further IOL tilting or decentration.

Mechanical characterisation of hydrophobic and hydrophilic acrylates used in intraocular lenses through depth sensing indentation

In this work, the mechanical behaviour of hydrophilic and hydrophobic acrylates has been characterised by depth sensing indentation. Time-dependent behaviour has been studied using load-relaxation tests. Experiments have been simulated with a finite element software using a visco-hyperelastic material model. The parameters of this model have been determined using deep learning techniques. The developed material models have been used to mechanically simulate a standard compression test of a prototype intraocular lens.

Axisymmetric Finite Element Modelling of the Human Lens Complex under Cataract Surgery

Cataract is a disease opacifying the crystalline, leading to a blurred vision and ultimately to blindness. With an aging population, the incidence of cataract is increasing, as well as the number of treatments. The solution available is its complete removal, followed by an implant of an intraocular lens (IOL). Although the post-operative complications on cataract surgeries have been decreasing in general, the bag-IOL complex dislocation is still an issue, probably being the most serious complication under this procedure. In this work, an axisymmetric Finite Element (FE) modelling strategy of the crystalline complex during the process of accommodation under cataract surgery is proposed. The goal was to understand the influence of biomechanical alterations promoted by the IOL on bag-IOL dislocation after surgery. An increase of force and stress in the zonules was verified in the pseudophakic eye compared to the complete eye, which could explain why zonules break years after surgery, leading to the bag-IOL dislocation. The axisymmetric FE model proposed in this work is innovative in this field, which still lacks detailed research, and can be an important complement for the clinical and biomechanical work on the crystalline complex.

Effect of haptic geometry in C-loop intraocular lenses on optical quality

The biomechanical stability of intraocular lenses (IOLs) must achieve high-quality optical performance and clinical outcomes after cataract surgery. For this reason, the quality and performance features of the IOLs should be previously analysed following the Standard ISO 11979-2 and ISO 11979-3. The ISO 11979-3 tries to reproduce the behaviour of the IOL in the capsular bag by compressing the lens between two clamps. With this test, it has been demonstrated that the haptic design is a crucial factor to obtain biomechanical stability. Hence, the main goal of this study was to design an aberration-free aspheric IOL and to study the influence of haptic geometry on the optical quality. For that purpose, 5 hydrophobic IOLs with different haptic design were manufactured and their biomechanical stability was compared experimentally and numerically. The IOLs were classified as stiff and flexible designs depending on their haptic geometry. The biomechanical response was measured by means of the compression force, the axial displacement, the angle of contact or contact area, the decentration, the tilt and the strain energy. The results suggest that in vitro and in silico compression tests present similar responses for the IOLs analysed. Furthermore, the flexible IOL designs presented better biomechanical stability than stiff designs. These results were correlated with the optical performance, where the optical quality decreases with worst biomechanical stability. This numerical methodology provides an indisputable advance regarding IOL designs, leading to reduce costs by exploring a feasible space of solutions during the product design process and prior to manufacturing.

Biomechanical Stability of Three Intraocular Lenses With Different Haptic Designs: In Silico and In Vivo Evaluation

PURPOSE

To assess the biomechanical stability of three different marketed intraocular lenses (IOLs) with different haptic designs (four-loop IOL [Micro F FineVision model] and double C-loop IOL [POD F and POD FT models], all manufactured by PhysIOL), in silico (computer simulation) and in vivo (in the context of lens surgery).

METHODS

An in silico simulation investigation was performed using finite element modeling (FEM) software to reproduce the compression test defined by the International Organization for Standardization and in vivo implantation in patients in the context of lens surgery was evaluated 1 day and 3 months postoperatively. IOL decentration and rotation were tested. In addition, the stress and strains were analyzed with the finite element method.

RESULTS

In the in silico evaluation, the compression force for the POD F IOL was slightly lower than for the POD FT IOL and Micro F IOL for all compression diameters. The axial displacement was maximum for the POD FT IOL and the tilt, rotation, and lateral decentration were substantially lower than the acceptable tolerance limits established in ISO 11979-2. In the in vivo evaluation, a total of 45 eyes from 45 patients were selected, 15 eyes for each IOL model under assessment. Statistically significant differences were found between the Micro F and POD F IOLs for lateral decentration in x-direction (in absolute value) at 3 months postoperatively (P = .03).

CONCLUSIONS

Although statistically significant differences have been found when comparing the displacement, tilt, and rotation between the different lenses, these differences cannot be considered clinically relevant, which would suggest that all three IOL models yield excellent stability in those terms. FEM appears to be a powerful tool for numerical studies of the biomechanical properties of IOLs. [J Refract Surg. 2020;36(9):617-624.].

Clinical outcomes of Ankoris toric intraocular lens implantation using a computer-assisted marker system

PURPOSE

To report the clinical outcomes of patients who underwent cataract surgery with implantation of Ankoris monofocal toric intraocular lens (IOL) (PhysIOL SA, Liège, Belgium) using the Zeiss Callisto Eye (Carl Zeiss AG, Dublin, CA).

METHODS

We conducted a retrospective case series of patients who underwent routine cataract extraction and implantation of Ankoris toric IOL using the Zeiss Callisto eye between January 2018 and December 2018 by four senior surgeons. Patients' medical records were reviewed, and clinical outcomes including postoperative refraction, visual acuity outcomes, IOL position and deviation from planned axis were collected.

RESULTS

Fifty-six eyes of 56 patients were included, 48% were female, and the mean age was 70 ± 8 years. Patients with pseudoexfoliation syndrome, glaucoma or keratoconus were excluded from the study. Pre-operative mean corneal astigmatism was 2.38 ± 0.78 diopters (D), and mean implanted IOL cylindrical power was 3.06 ± 1.07 D. IOL rotation 30 days postoperatively was within 5° in 82% of eyes and between 6° and 10° in 10.8% of eyes. Mean postoperative refractive astigmatism 30 days postoperatively was 0.22 ± 0.36 D; in 84% of eyes the postoperative refractive astigmatism was ≤ 0.50 D. IOL rotation significantly increased between day 1 to day 7 postoperatively (1.91 ± 3.15° to 3.18 ± 3.3°, P = 0.001). However, no significant rotation had occurred between day 7 and day 30 postoperatively (P = 0.093).

CONCLUSION

Cataract surgery with implantation of Ankoris monofocal toric IOL using the Zeiss Callisto Eye marking system is predictable and effective in reducing refractive astigmatism.

Systematic Study on the Biomechanical Stability of C-Loop Intraocular Lenses: Approach to an Optimal Design of the Haptics

To study the main design parameters that affect the mechanical stability of C-loop intraocular lenses, leading to an optimal design that minimizes the axial displacement, tilt and rotation. A total of 144 geometrical variations were studied on a 1-piece, non-angulated, C-loop hydrophobic acrylate intraocular lens. The study was performed in a finite element modeling simulation. The suitable set of variations was determined using a mixed-factorial analysis, allowing to analyse the impact of the different designs on the mechanical stability of the lens (compression force, axial displacement, tilt and rotation). The design parameters under study were: the length, width, thickness and opening angle of the haptic, the haptic-optic junction and the start of the haptic curvature. The compression (or reaction) force is affected by the haptic width, the haptic-optic junction, and the interaction between both. The axial displacement is mainly affected by the width and thickness of the haptic, and the size of the haptic-optic junction as well. The tilt is affected by the haptic thickness and the interaction between the haptic curvature and the haptic-optic junction. The rotation is affected by the start of the haptic curvature, the haptic-optic junction and the haptic width. The haptic-optic juntion is one of the most influential parameters affecting the four responses studied of the C-Loop IOL. The smaller the haptic-optic juntion, the better biomechanical stability.

Myo/Nog cells are present in the ciliary processes, on the zonule of Zinn and posterior capsule of the lens following cataract surgery

Myo/Nog cells, named for their expression of MyoD and noggin, enter the eye during early stages of embryonic development. Their release of noggin is critical for normal morphogenesis of the lens and retina. Myo/Nog cells are also present in adult eyes. Single nucleated skeletal muscle cells designated as myofibroblasts arise from Myo/Nog cells in cultures of lens tissue. In this report we document the presence of Myo/Nog cells in the lens, ciliary body and on the zonule of Zinn in mice, rabbits and humans. Myo/Nog cells were rare in all three structures. Their prevalence increased in the lens and ciliary body of rabbits 24 h following cataract surgery. Rabbits developed posterior capsule opacification (PCO) within one month of surgery. The number of Myo/Nog cells continued to be elevated in the lens and ciliary body. Myo/Nog cells containing alpha smooth muscle actin and striated muscle myosin were present on the posterior capsule and overlaid deformations in the capsule. Myo/Nog cells also were present on the zonule fibers and external surface of the posterior capsule. These findings suggest that Myo/Nog contribute to PCO and may use the zonule fibers to migrate between the ciliary processes and lens.

Influence of material and haptic design on the mechanical stability of intraocular lenses by means of finite-element modeling

Intraocular lenses (IOLs) are used in the cataract treatment for surgical replacement of the opacified crystalline lens. Before being implanted they have to pass the strict quality control to guarantee a good biomechanical stability inside the capsular bag, avoiding the rotation, and to provide a good optical quality. The goal of this study was to investigate the influence of the material and haptic design on the behavior of the IOLs under dynamic compression condition. For this purpose, the strain-stress characteristics of the hydrophobic and hydrophilic materials were estimated experimentally. Next, these data were used as the input for a finite-element model (FEM) to analyze the stability of different IOL haptic designs, according to the procedure described by the ISO standards. Finally, the simulations of the effect of IOL tilt and decentration on the optical performance were performed in an eye model using a ray-tracing software. The results suggest the major importance of the haptic design rather than the material on the postoperative behavior of an IOL. FEM appears to be a powerful tool for numerical studies of the biomechanical properties of IOLs and it allows one to help in the design phase to the manufacturers.

Comparison of visual outcomes after implantation of diffractive trifocal toric intraocular lens and a diffractive apodized bifocal toric intraocular lens

Purpose

The aim of this study was to compare a new diffractive trifocal toric lens with an apodized diffractive bifocal toric lens in terms of refractive and visual acuity (VA) outcomes, including low-contrast VA (LCVA), as well as the patient’s visual function 3 months after implantation.

Patients and methods

This is a randomized prospective study involving bilateral implantation of a trifocal toric or a bifocal toric lens. At 3 months postoperatively, the subject’s vision was tested both uncorrected and with his/her best distance correction at: distance (4 m), intermediate (63 cm), and near (40 cm). Binocular defocus curves were measured with no correction and with the subject’s best distance correction in place. Quality of vision was measured using the National Eye Institute Visual Function Questionnaire.

Results

A total of 22 patients were enrolled (eleven in each group). There was no statistically significant difference in the absolute change in measured rotation between 1 month and 3 months postoperatively between the two intraocular lens (IOL) groups (P=0.98). At 3 months, the postoperative refraction and distance VA by eye were similar between groups. There was no statistically significant difference in the measured LCVA between groups (P=0.39). The defocus curve showed that at 67 cm, the trifocal toric lens had statistically significantly better VA when compared to the bifocal toric lens. There were no statistically significant differences by group for any of the National Eye Institute Visual Function Questionnaire scores (P>0.26 in all cases).

Conclusion

The trifocal toric IOL improved the intermediate vision without negatively impacting visual function and distance, near, or low-contrast VA when compared to a bifocal toric IOL. The toric component of the trifocal lens effectively reduced astigmatism and provided good rotational stability.