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Schumacher J, Lopez RR, Larin K, Manns F, Scarcelli G. Functional effects of the spatial-varying lens mechanical properties in accommodation. JPHYS PHOTONICS 2024; 6:035021. [PMID: 38975030 PMCID: PMC11223182 DOI: 10.1088/2515-7647/ad3e55] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 03/25/2024] [Accepted: 04/12/2024] [Indexed: 07/09/2024] Open
Abstract
Lens biomechanical properties are critical for our eyes to accommodate. While it is well understood that lens mechanical properties change with age, different experimental techniques have been used over the years, with varying results on how the lens modulus changes. In this study, we developed a spatial-varying elasticity model to characterize the overall elastic modulus of the lens and establish its effect on accommodation. First, to validate the model, ex vivo porcine lenses underwent compression testing using biopsy punches of different diameters to change the percentage of nucleus within samples. Importantly, we found that, indeed, changing nucleus/cortex spatial ratio produces dramatic (∼7-fold) increase in overall sample modulus. Comparing the model with human lens spatial ratios, we demonstrate how changing spatial mechanics are more influential than peak modulus changes on overall elastic modulus. Next, in vivo clinical measurements of the spatial-varying lens modulus were used to generate a simplified mechanical-optical model of accommodation. We defined an ellipsoid lens with patient-derived modulus and geometry measurements, and a statics simulation and ray tracing analysis were performed through the deformed and undeformed lens. The resulting accommodation estimates agree with general accommodation expectations.
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Affiliation(s)
- Justin Schumacher
- Fischell Department of Bioengineering, University of Maryland, College Park, United States of America
| | - Raymundo Rodriguez Lopez
- Fischell Department of Bioengineering, University of Maryland, College Park, United States of America
| | - Kirill Larin
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States of America
| | - Fabrice Manns
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, United States of America
- Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States of America
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park, United States of America
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2
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Davies LN, Biswas S, Bullimore M, Cruickshank F, Estevez JJ, Khanal S, Kollbaum P, Marcotte-Collard R, Montani G, Plainis S, Richdale K, Simard P, Wolffsohn JS. BCLA CLEAR presbyopia: Mechanism and optics. Cont Lens Anterior Eye 2024:102185. [PMID: 38796331 DOI: 10.1016/j.clae.2024.102185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2024]
Abstract
With over a billion adults worldwide currently affected, presbyopia remains a ubiquitous, global problem. Despite over a century of study, the precise mechanism of ocular accommodation and presbyopia progression remains a topic of debate. Accordingly, this narrative review outlines the lenticular and extralenticular components of accommodation together with the impact of age on the accommodative apparatus, neural control of accommodation, models of accommodation, the impact of presbyopia on retinal image quality, and both historic and contemporary theories of presbyopia.
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Affiliation(s)
- Leon N Davies
- School of Optometry, College of Health and Life Sciences, Aston University, Birmingham, UK.
| | - Sayantan Biswas
- School of Optometry, College of Health and Life Sciences, Aston University, Birmingham, UK
| | | | - Fiona Cruickshank
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, UK
| | - Jose J Estevez
- Caring Futures Institute, College of Nursing and Health Sciences, Optometry and Vision Science, Flinders University, Adelaide, Australia; Flinders Centre for Ophthalmology, Eye and Vision Research, Department of Ophthalmology, Flinders University, Adelaide, Australia
| | - Safal Khanal
- Department of Optometry and Vision Science, The University of Alabama at Birmingham, USA
| | | | | | | | - Sotiris Plainis
- Laboratory of Optics and Vision, School of Medicine, University of Crete, Greece
| | | | - Patrick Simard
- School of Optometry, Universite de Montreal, Montreal, Quebec, Canada
| | - James S Wolffsohn
- School of Optometry, College of Health and Life Sciences, Aston University, Birmingham, UK
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3
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Wilkie IC. Basement Membranes, Brittlestar Tendons, and Their Mechanical Adaptability. BIOLOGY 2024; 13:375. [PMID: 38927255 PMCID: PMC11200632 DOI: 10.3390/biology13060375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 05/20/2024] [Accepted: 05/21/2024] [Indexed: 06/28/2024]
Abstract
Basement membranes (BMs) are thin layers of extracellular matrix that separate epithelia, endothelia, muscle cells, and nerve cells from adjacent interstitial connective tissue. BMs are ubiquitous in almost all multicellular animals, and their composition is highly conserved across the Metazoa. There is increasing interest in the mechanical functioning of BMs, including the involvement of altered BM stiffness in development and pathology, particularly cancer metastasis, which can be facilitated by BM destabilization. Such BM weakening has been assumed to occur primarily through enzymatic degradation by matrix metalloproteinases. However, emerging evidence indicates that non-enzymatic mechanisms may also contribute. In brittlestars (Echinodermata, Ophiuroidea), the tendons linking the musculature to the endoskeleton consist of extensions of muscle cell BMs. During the process of brittlestar autotomy, in which arms are detached for the purpose of self-defense, muscles break away from the endoskeleton as a consequence of the rapid destabilization and rupture of their BM-derived tendons. This contribution provides a broad overview of current knowledge of the structural organization and biomechanics of non-echinoderm BMs, compares this with the equivalent information on brittlestar tendons, and discusses the possible relationship between the weakening phenomena exhibited by BMs and brittlestar tendons, and the potential translational value of the latter as a model system of BM destabilization.
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Affiliation(s)
- Iain C Wilkie
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow G12 8QQ, UK
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4
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Ghaderi H, Ní Dhubhghaill S, Tassignon MJ, Van Os L, Koppen C, Rozema JJ. The potential influence of the ligament of Wieger on the crystalline lens shape. Sci Rep 2024; 14:4004. [PMID: 38369631 PMCID: PMC10874931 DOI: 10.1038/s41598-024-54674-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 02/15/2024] [Indexed: 02/20/2024] Open
Abstract
This research uses mathematical modelling to evaluate the influence of the ligament of Wieger on the crystalline lens shape at rest, and during accommodation. An axisymmetric model of the anterior segment, including the ligament of Wieger, was created using the finite element method. Different conditions including variations of stiffness and positions of the ligament, with and without the ligament, were tested to see how they affected lens curvature and optical power. Adding the ligament of Wieger to the simulation had a noticeable impact on the optical power of the lens, particularly on the posterior surface power and total power. Ligament stiffness and width significant influenced the accommodative range of the eye by - 0.95D and - 2.39D for ligaments with the same and 3× the stiffness of the capsular bag, respectively. Ligament width and inner diameter had negligible effects on lens thickness but did have significant effects on posterior surface power and accommodation. In this simulation, we found that the ligament of Wieger can significantly affect the lens shape, both at rest and during accommodation, and may need to be considered in lens models.
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Affiliation(s)
- Hosna Ghaderi
- Visual Optics Lab Antwerp (VOLANTIS), Faculty of Medicine and Health Sciences, University of Antwerp, Wilrijk, Belgium
| | - Sorcha Ní Dhubhghaill
- Visual Optics Lab Antwerp (VOLANTIS), Faculty of Medicine and Health Sciences, University of Antwerp, Wilrijk, Belgium
- Department of Ophthalmology, Brussels University Hospital, Brussels, Belgium
| | | | - Luc Van Os
- Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium
| | - Carina Koppen
- Visual Optics Lab Antwerp (VOLANTIS), Faculty of Medicine and Health Sciences, University of Antwerp, Wilrijk, Belgium
- Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium
| | - Jos J Rozema
- Visual Optics Lab Antwerp (VOLANTIS), Faculty of Medicine and Health Sciences, University of Antwerp, Wilrijk, Belgium.
- Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium.
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5
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Knaus KR, Hipsley A, Blemker SS. A new look at an old problem: 3D modeling of accommodation reveals how age-related biomechanical changes contribute to dysfunction in presbyopia. Biomech Model Mechanobiol 2024; 23:193-205. [PMID: 37733144 DOI: 10.1007/s10237-023-01767-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 08/17/2023] [Indexed: 09/22/2023]
Abstract
Presbyopia is an age-related ocular disorder where accommodative ability declines so that an individual's focusing range is insufficient to provide visual clarity for near and distance vision tasks without corrective measures. With age, the eye exhibits changes in biomechanical properties of many components involved in accommodation, including the lens, sclera, and ciliary muscle. Changes occur at different rates, affecting accommodative biomechanics differently, but individual contributions to presbyopia are unknown. We used a finite element model (FEM) of the accommodative mechanism to simulate age-related changes in lens stiffness, scleral stiffness, and ciliary contraction to predict differences in accommodative function. The FEM predicts how ciliary muscle action leads to lens displacement by initializing a tensioned unaccommodated lens (Phase 0) then simulating ciliary muscle contraction in accommodation (Phase 1). Model inputs were calibrated to replicate experimentally measured lens and ciliary muscle in 30-year-old eyes. Predictions of accommodative lens deformation were verified with additional imaging studies. Model variations were created with altered lens component stiffnesses, scleral stiffness, or ciliary muscle section activations, representing fifteen-year incremental age-related changes. Model variations predict significant changes in accommodative function with age-related biomechanical property changes. Lens changes only significantly altered lens thickening with advanced age (46% decrease at 75 years old) while sclera changes produced progressive dysfunction with increasing age (23%, 36%, 49% decrease at 45, 60, and 75 years old). Ciliary muscle changes effected lens position modulation. Model predictions identified potential mechanisms of presbyopia that likely work in combination to reduce accommodative function and could indicate effectiveness of treatment strategies and their dependency on patient age or relative ocular mechanical properties.
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Affiliation(s)
- Katherine R Knaus
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | | | - Silvia S Blemker
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA.
- Department of Ophthalmology, University of Virginia, 415 Lane Road, MR5 Room 2133, Box 800759, Charlottesville, VA, USA.
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Holland E, Karpecki P, Fingeret M, Schaeffer J, Gupta P, Fram N, Smits G, Ignacio T, Lindstrom R. Efficacy and Safety of CSF-1 (0.4% Pilocarpine Hydrochloride) in Presbyopia: Pooled Results of the NEAR Phase 3 Randomized, Clinical Trials. Clin Ther 2024; 46:104-113. [PMID: 38216351 DOI: 10.1016/j.clinthera.2023.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 01/14/2024]
Abstract
PURPOSE This study was undertaken to evaluate the safety and efficacy of CSF-1 (0.4% pilocarpine hydrochloride ophthalmic solution) for use in individuals with presbyopia. METHODS Two Phase 3 multicenter, randomized, double-masked, vehicle-controlled, parallel-group clinical trials were conducted in 35 private ophthalmology clinics in the United States from October 2020 to February 2022. Key inclusion criteria were the following: (1) age 45-64 years, (2) distance-corrected near visual acuity (DCNVA) at 40 cm ≥0.40 and ≤0.90 logarithm of the minimum angle of resolution (logMAR, approximately 20/50-20/160 Snellen) in at least 1 eye, (3) manifest refraction (MR) between -4.50 and +2.00 diopter (D) sphere in each eye with ≤2.00D difference between eyes, (4) <2.00D of cylinder MR in each eye, (5) ≤0.04 logMAR (20/20-2 or better) corrected distance visual acuity (CDVA) at 4 m in each eye. Key exclusion criteria were the following: (1) >0.14 logMAR (7 letters) improvement in post-vehicle treatment in monocular DCNVA in either eye at visit 1, (2) introcular pressure (IOP) <9 or >22 mm Hg, (3) average dark-adapted pupillometry <3.5 mm in either eye, (4) prior refractive surgery or intraocular lens (IOL) implantation. Participants applied CSF-1 or vehicle twice per day for 2 weeks. Efficacy and safety assessments were performed at several times on days 1, 8, and 15. Response was defined as ≥3-line gain in DCNVA without loss of ≥1-line in CDVA in the study eye under mesopic room lighting conditions. The primary efficacy endpoint was measured 1 hour post-dose 1 on day 8. Key secondary endpoints were 2 hours post-dose 1, and 1 and 2 hours post-dose 2, also on day 8. Safety endpoints were ocular and non-ocular treatment-related adverse events (TRAE), conjunctival redness, drop comfort, slit-lamp biomicroscopy, intraocular pressure, indirect fundoscopy, and CDVA at 4 m. FINDINGS Six hundred thirteen participants were randomized to CSF-1 (n = 309) or vehicle (n = 304). Participants were predominantly White (80.8%) and female (62.0%), with mean age (standard deviation) of 54.7 (4.8). CSF-1 met the primary and key secondary endpoints. At the primary endpoint, 40.1% of the CSF-1 group achieved response versus 19.1% of the vehicle group (P < 0.0001). The percentage of responders was significantly greater in CSF-1 compared with vehicle at all tested times. Changes from baseline in all safety endpoints were comparable between groups. Most adverse events (AEs) were mild and transient. Neither serious nor severe AEs were reported with CSF-1. IMPLICATIONS CSF-1, a low-dose pilocarpine ophthalmic solution, demonstrated superiority to vehicle in improving near vision in individuals with presbyopia without compromising distance vision. CSF-1 demonstrated a favorable safety profile. CLINICALTRIALS gov identifier: NCT04599933 (NEAR-1), NCT04599972 (NEAR-2).
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Affiliation(s)
| | - Paul Karpecki
- The Kentucky College of Optometry, University of Pikeville, KY
| | - Murray Fingeret
- Department of Veterans Administration New York Harbor Health Care System, New York, NY
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7
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Rodriguez J, Tan Q, Šikić H, Taber LA, Bassnett S. The effect of fibre cell remodelling on the power and optical quality of the lens. J R Soc Interface 2023; 20:20230316. [PMID: 37727073 PMCID: PMC10509584 DOI: 10.1098/rsif.2023.0316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 08/22/2023] [Indexed: 09/21/2023] Open
Abstract
Vertebrate eye lenses are uniquely adapted to form a refractive index gradient (GRIN) for improved acuity, and to grow slowly in size despite constant cell proliferation. The mechanisms behind these adaptations remain poorly understood. We hypothesize that cell compaction contributes to both. To test this notion, we examined the relationship between lens size and shape, refractive characteristics and the cross-sectional areas of constituent fibre cells in mice of different ages. We developed a block-face imaging method to visualize cellular cross sections and found that the cross-sectional areas of fibre cells rose and then decreased over time, with the most significant reduction occurring in denucleating cells in the adult lens cortex, followed by cells in the embryonic nucleus. These findings help reconcile differences between the predictions of lens growth models and empirical data. Biomechanical simulations suggested that compressive forces generated from continuous deposition of fibre cells could contribute to cellular compaction. However, optical measurements revealed that the GRIN did not mirror the pattern of cellular compaction, implying that compaction alone cannot account for GRIN formation and that additional mechanisms are likely to be involved.
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Affiliation(s)
- J. Rodriguez
- Department of Basic Sciences, University of Health Sciences and Pharmacy in St. Louis, 1 Pharmacy Place, St. Louis, MO 63110, USA
| | - Q. Tan
- Department of Ophthalmology & Visual Sciences, Washington University School of Medicine, 660 South Euclid Ave, Campus Box 8096, St. Louis, MO 63110, USA
| | - H. Šikić
- Department of Mathematics, Faculty of Science, University of Zagreb, Zagreb, Croatia
| | - L. A. Taber
- Department of Biomedical Engineering, Washington University, St. Louis, MO 63130, USA
| | - S. Bassnett
- Department of Ophthalmology & Visual Sciences, Washington University School of Medicine, 660 South Euclid Ave, Campus Box 8096, St. Louis, MO 63110, USA
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8
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Fernandez-Bueno I, Olcina LI, Andrés-Iglesias C, Puertas-Neyra K, Fernández-Martínez I, Usategui-Martín R, Maldonado-López MJ. Safety, biocompatibility, and potential functionality of a new accommodative intraocular lens: An experimental study in rabbits. Heliyon 2023; 9:e19604. [PMID: 37810139 PMCID: PMC10558835 DOI: 10.1016/j.heliyon.2023.e19604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 08/21/2023] [Accepted: 08/28/2023] [Indexed: 10/10/2023] Open
Abstract
This study aims to evaluate the safety, biocompatibility, and functionality of a new accommodative intraocular lens (IOL) (LUZ, patent PCT/ES2016/070,813) after implantation in rabbit eyes. LUZ (Study) and EyeCee® plus a capsular ring (Control) were implanted in rabbits (n = 8 each) after phacoemulsification. Intraoperative follow-up, long-term clinical follow-up, and functional IOL studies were carried out periodically for up to 180 days. A macroscopic examination of the eyeballs to reveal abnormalities and determine the implant centering and a microscopic examination to semi-quantify cell and tissue response were performed. Statistical analysis of the collected data was finally achieved. During follow-up, no significant changes in the general condition nor the clinical evaluation were observed between both groups. However, Study IOL remained centered throughout the study and did not present severe complications as observed in the Control group. Functional studies did not reveal significant differences between both materials. Study showed better centering, fewer adhesions, and maintenance of an opening capsular bag compared to the Control. Local biological effects caused by Study implantation are minimal and comparable to the Control. Therefore, LUZ showed no clinical signs or histological response of adverse reaction to the implanted material, according to UNE-EN ISO 11979-5 and 10993-6. Functionality must be confirmed in another animal species with greater lens accommodation capacity than the rabbit. LUZ keeps the capsular bag open, favoring its centering and avoiding fibrosis and adherence to the bag; this allows potential accommodation of this IOL and theoretically enables the patient to focus dynamically.
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Affiliation(s)
- Ivan Fernandez-Bueno
- Instituto Universitario de Oftalmobiología Aplicada (IOBA), Retina Group, Universidad de Valladolid, 47011 Valladolid, Spain
- RICORS Inflamación e inmunopatología de órganos y sistemas (RD21/0002/0017), National Institute of Health Carlos III, Madrid, Spain
| | | | - Cristina Andrés-Iglesias
- Instituto Universitario de Oftalmobiología Aplicada (IOBA), Retina Group, Universidad de Valladolid, 47011 Valladolid, Spain
| | - Kevin Puertas-Neyra
- Instituto Universitario de Oftalmobiología Aplicada (IOBA), Retina Group, Universidad de Valladolid, 47011 Valladolid, Spain
| | - Itziar Fernández-Martínez
- Instituto Universitario de Oftalmobiología Aplicada (IOBA), Retina Group, Universidad de Valladolid, 47011 Valladolid, Spain
- CIBER BBN, National Institute of Health Carlos III, Madrid, Spain
| | - Ricardo Usategui-Martín
- Instituto Universitario de Oftalmobiología Aplicada (IOBA), Retina Group, Universidad de Valladolid, 47011 Valladolid, Spain
- RICORS Inflamación e inmunopatología de órganos y sistemas (RD21/0002/0017), National Institute of Health Carlos III, Madrid, Spain
- Departamento de Biología Celular, Histología y Farmacología, Universidad de Valladolid, 47005 Valladolid, Spain
| | - Miguel José Maldonado-López
- Instituto Universitario de Oftalmobiología Aplicada (IOBA), Retina Group, Universidad de Valladolid, 47011 Valladolid, Spain
- RICORS Inflamación e inmunopatología de órganos y sistemas (RD21/0002/0017), National Institute of Health Carlos III, Madrid, Spain
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9
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Wang K, Xia Y, Wang X, Pu Y, Zhao Y, Chang P, Pierscionek BK, Fan Y. Influence of design parameters and capsulorhexis on intraocular lens stabilities: A 3D finite element analysis. Comput Biol Med 2023; 160:106972. [PMID: 37120989 DOI: 10.1016/j.compbiomed.2023.106972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/17/2023] [Accepted: 04/22/2023] [Indexed: 05/02/2023]
Abstract
BACKGROUND Current treatment of cataract widely used in clinics is by removal of the opacified content from the lens capsule which is followed by insertion of an artificial intraocular lens (IOL). The IOL needs to remain stabilized in the capsular bag for the eye to achieve desired optical quality. The present study aims to investigate how different design parameters of the IOL can influence the axial and rotational stabilities of IOLs using Finite Element Analysis. METHODS Eight designs of IOL with variations in types of optics surface, types of haptics and haptic angulation were constructed using parameters obtained from an online IOL databank (IOLs.eu). Each IOL was subjected to compressional simulations both by two clamps and by a collapsed natural lens capsule with an anterior rhexis. Comparisons were made between the two scenarios on axial displacement, rotation, and distribution of stresses. RESULTS The clamps compression method set out by ISO does not always produce the same outcome as the in-the-bag analysis. The open-loop IOLs show better axial stability while the closed-loop IOLs show better rotational stability when compressed by two clamps. Simulations of IOL in the capsular bag only demonstrate better rotational stability for closed-loop designs. CONCLUSIONS The rotational stability of an IOL is largely dependent on its haptic design whilst the axial stability is affected by the appearance of the rhexis to the anterior capsule which has a major influence on designs with a haptic angulation.
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Affiliation(s)
- Kehao Wang
- Key Laboratory for Biomechanics and Mechanobiology of Ministry for Education, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, China; School of Engineering Medicine, Beihang University, Beijing, China
| | - Yunxin Xia
- Key Laboratory for Biomechanics and Mechanobiology of Ministry for Education, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, China; School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Xiaofei Wang
- Key Laboratory for Biomechanics and Mechanobiology of Ministry for Education, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, China; School of Biological Science and Medical Engineering, Beihang University, Beijing, China.
| | - Yutian Pu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry for Education, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, China; School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Yune Zhao
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Pingjun Chang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Barbara K Pierscionek
- Faculty of Health, Education, Medicine and Social Care, Medical Technology Research Centre, Anglia Ruskin University, Bishops Hall Lane, Chelmsford, United Kingdom
| | - Yubo Fan
- Key Laboratory for Biomechanics and Mechanobiology of Ministry for Education, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, China; School of Engineering Medicine, Beihang University, Beijing, China; School of Biological Science and Medical Engineering, Beihang University, Beijing, China.
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10
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Abstract
Purpose: Presbyopia-the progressive loss of near focus with age-is primarily a result of changes in lens biomechanics. In particular, the shape of the ocular lens in the absence of zonular tension changes significantly throughout adulthood. Contributors to this change in shape are changes in lens biomechanical properties, continuous volumetric growth lens, and possibly remodeling of the lens capsule. Knowledge in this area is growing rapidly, so the purpose of this mini-review was to summarize and synthesize these gains.Methods: We review the recent literature in this field.Results: The mechanisms governing age-related changes in biomechanical properties remains unknown. We have recently shown that lens growth may be driven by zonular tension. The same mechanobiological mechanism driving lens growth may also lead to remodeling of the capsule, though this remains to be demonstrated.Conclusions: This mini-review focuses on identifying mechanisms which cause these age-related changes, suggesting future work which may elucidate these mechanisms, and briefly discusses ongoing efforts to develop a non-surgical approach for therapeutic management of presbyopia. We also propose a simple model linking lens growth and biomechanical properties.
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Affiliation(s)
- Wade Rich
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
| | - Matthew A Reilly
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA.,Department of Ophthalmology & Visual Sciences, The Ohio State University, Columbus, OH, USA
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11
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Design of an Automatically Controlled Multi-Axis Stretching Device for Mechanical Evaluations of the Anterior Eye Segment. Bioengineering (Basel) 2023; 10:bioengineering10020142. [PMID: 36829636 PMCID: PMC9952546 DOI: 10.3390/bioengineering10020142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/14/2023] [Accepted: 01/18/2023] [Indexed: 01/22/2023] Open
Abstract
The young eye has an accommodative ability involving lens shape changes to focus over different distances. This function gradually decreases with age, resulting in presbyopia. Greater insights into the mechanical properties of anterior eye structures can improve understanding of the causes of presbyopia. The present study aims to develop a multi-axis stretching device for evaluating the mechanical properties of the intact eye lens. A stretching device integrating the mechanical stretcher, motor, torque sensor and data transmission mechanism was designed and developed by 3D printing. The mechanical stretcher can convert rotation into radial movement, both at constant speeds, according to the spiral of Archimedes. The loading unit equipped with eight jaws can hold the eye sample tightly. The developed device was validated with a spring of known constant and was further tested with anterior porcine eye segments. The validation experiment using the spring resulted in stiffness values close to the theoretical spring constant. Findings from measurements with porcine eye samples indicated that the measured forces are within the ranges reported in the literature. The developed multi-axis stretching device has good repeatability during experiments with similar settings and can be reliably used for mechanical evaluations of the intact eye lens.
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12
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Xu J, Jiang Y, Gao L. Synthetic strain-stiffening hydrogels towards mechanical adaptability. J Mater Chem B 2023; 11:221-243. [PMID: 36507877 DOI: 10.1039/d2tb01743a] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Living organisms are made of wet, soft tissues. However, there is only one candidate to simultaneously replicate the mechanical and composition features of load-bearing tissues, that is, strain-stiffening hydrogels. The conventional mechanical match design principle is mostly limited to stiffness matching. However, this strategy cannot sufficiently and necessarily lead to mechanical matching over the whole physiologic deformation period for tissues and damages the tissues over time. In this review, we aim to provide a comprehensive summary of the reported synthetic strain-stiffening hydrogels and particularly focus on the relationship between their structure and performance. Initially, we present a brief introduction on the significance of strain-stiffening hydrogels in mimicking the mechanics of tissues, and then we discuss the qualitative evaluation of the strain-stiffening behaviors to guide the design of materials towards mimicking soft tissue. After distinguishing the mechanical testing methods, we focus on the methods for the preparation of typical strain-stiffening hydrogels based on categories, such as network without strand entanglement, semiflexible network, and anisotropic networks. Subsequently, we discuss the structural evolution of strain-stiffening hydrogels. We hope that this review will serve as an updated introduction and reference for researchers who are interested in exploring strain-stiffening hydrogels as tissue-mimics for addressing the societal needs at various frontiers.
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Affiliation(s)
- Jingyu Xu
- School of Light Industry and Chemical Engineering, Guangdong University of Technology, Guangzhou 510006, China.
| | - Yin Jiang
- School of Light Industry and Chemical Engineering, Guangdong University of Technology, Guangzhou 510006, China.
| | - Liang Gao
- School of Light Industry and Chemical Engineering, Guangdong University of Technology, Guangzhou 510006, China. .,Jieyang Branch of Chemistry and Chemical Engineering Guangdong Laboratory (Rongjiang Laboratory), Jieyang 515200, China
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13
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Redaelli E, Grasa J, Calvo B, Rodriguez Matas JF, Luraghi G. A detailed methodology to model the Non Contact Tonometry: a Fluid Structure Interaction study. Front Bioeng Biotechnol 2022; 10:981665. [PMID: 36267451 PMCID: PMC9576856 DOI: 10.3389/fbioe.2022.981665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 09/13/2022] [Indexed: 11/21/2022] Open
Abstract
Understanding the corneal mechanical properties has great importance in the study of corneal pathologies and the prediction of refractive surgery outcomes. Non-Contact Tonometry (NCT) is a non-invasive diagnostic tool intended to characterize the corneal tissue response in vivo by applying a defined air-pulse. The biomarkers inferred from this test can only be considered as indicators of the global biomechanical behaviour rather than the intrinsic biomechanical properties of the corneal tissue. A possibility to isolate the mechanical response of the corneal tissue is the use of an inverse finite element method, which is based on accurate and reliable modelling. Since a detailed methodology is still missing in the literature, this paper aims to construct a high-fidelity finite-element model of an idealized 3D eye for in silico NCT. A fluid-structure interaction (FSI) simulation is developed to virtually apply a defined air-pulse to a 3D idealized eye model comprising cornea, limbus, sclera, lens and humors. Then, a sensitivity analysis is performed to examine the influence of the intraocular pressure (IOP) and the structural material parameters on three biomarkers associated with corneal deformation. The analysis reveals the requirements for the in silico study linked to the correct reproduction of three main aspects: the air pressure over the cornea, the biomechanical properties of the tissues, and the IOP. The adoption of an FSI simulation is crucial to capture the correct air pressure profile over the cornea as a consequence of the air-jet. Regarding the parts of the eye, an anisotropic material should be used for the cornea. An important component is the sclera: the stiffer the sclera, the lower the corneal deformation due to the air-puff. Finally, the fluid-like behavior of the humors should be considered in order to account for the correct variation of the IOP during the test which will, otherwise, remain constant. The development of a strong FSI tool amenable to model coupled structures and fluids provides the basis to find the biomechanical properties of the corneal tissue in vivo.
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Affiliation(s)
- Elena Redaelli
- Aragón Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain
- *Correspondence: Elena Redaelli,
| | - Jorge Grasa
- Aragón Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain
- Centro de Investigación Biomecánica en Red en Bioingenieria, Biomateriales y Nanomedicina (CIBER-BBN), Zaragoza, Spain
| | - Begoña Calvo
- Aragón Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain
- Centro de Investigación Biomecánica en Red en Bioingenieria, Biomateriales y Nanomedicina (CIBER-BBN), Zaragoza, Spain
| | - Jose Felix Rodriguez Matas
- LaBS, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milan, Italy
| | - Giulia Luraghi
- LaBS, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milan, Italy
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14
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Croft MA, Nork TM, Heatley G, Mcdonald JP, Katz A, Kaufman PL. Intraocular accommodative movements in monkeys; relationship to presbyopia. Exp Eye Res 2022; 222:109029. [PMID: 35283107 PMCID: PMC9749451 DOI: 10.1016/j.exer.2022.109029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 01/21/2022] [Accepted: 03/06/2022] [Indexed: 12/16/2022]
Abstract
Our goal was to quantify the age-related changes in the dynamic accommodative movements of the vitreous and aqueous humor in iridic, aniridic, phakic and aphakic primate eyes. Six bilaterally iridic and four bilaterally iridectomized rhesus monkeys, ranging in age from 6 to 25 years, received a stimulating electrode in the midbrain Edinger-Westphal nucleus to induce accommodation, measured by a Hartinger coincidence refractometer. One of the four iridectomized monkeys underwent unilateral extracapsular and another monkey underwent intracapsular lens extraction. Eyes were imaged utilizing specialized techniques and contrast agents to resolve intraocular structures. During accommodation the anterior hyaloid membrane and the posterior lens capsule bowed backward. Central vitreous fluid and structures/strands moved posteriorly toward the optic nerve region as peripheral vitreous, attached to the vitreous zonule, was pulled forward by ciliary muscle contraction. Triamcinolone particles injected intravitreally were also observed in the anterior chamber and moved from the anterior chamber toward the cleft of the anterior hyaloid membrane and then further posteriorly into the vitreous-filled cleft between the vitreous zonule and the ciliary body pars plana. These accommodative movements occurred in all eyes, and declined with age. There are statistically significant accommodative movements of various intravitreal structures. The posterior/anterior fluid flow between the anterior chamber and the vitreous compartments during accommodation/disaccommodation represents fluid displacement to allow/facilitate lens thickening. The posterior accommodative movement of central vitreous fluid may result from centripetal compression of the anterior tips of the cistern-like structure attached to the vitreous zonule, and posterior displacement of the central trunk of the cistern during ciliary muscle contraction and centripetal muscle movement. The findings may have implications for presbyopia.
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Affiliation(s)
- Mary Ann Croft
- Department of Ophthalmology and Visual Sciences, Madison, WI, 53792, USA.
| | - T Michael Nork
- Department of Ophthalmology and Visual Sciences, Madison, WI, 53792, USA
| | - Gregg Heatley
- Department of Ophthalmology and Visual Sciences, Madison, WI, 53792, USA
| | - Jared P Mcdonald
- Department of Ophthalmology and Visual Sciences, Madison, WI, 53792, USA
| | - Alexander Katz
- Department of Ophthalmology and Visual Sciences, Madison, WI, 53792, USA
| | - Paul L Kaufman
- Department of Ophthalmology and Visual Sciences, Madison, WI, 53792, USA; Wisconsin National Primate Research Center, Madison, WI, 53792, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, 53792, USA
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15
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Chu H, Zheng H, Miao A, Deng C, Sun N. Probing region-resolved heterogeneity of phosphoproteome in human lens by hybrid metal organic frameworks. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2022.07.059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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16
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Hirata A, Mine K, Hayashi K. Age-related appearance of lamellar structures in lens capsule of cataractous eyes and its pathological significance. J Cataract Refract Surg 2022; 48:844-849. [PMID: 35537866 DOI: 10.1097/j.jcrs.0000000000000967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Accepted: 05/05/2022] [Indexed: 11/26/2022]
Abstract
PURPOSE To determine morphological changes in the lens capsule with aging. SETTING Hayashi Eye Hospital, Fukuoka, Japan. DESIGN Cross-sectional study. METHODS 25 eyes from the older patient group (aged 80 years or older) and 25 eyes from the younger patient group (aged 65 years or younger) who were diagnosed with cataract and indicated for surgery were included in the study. After continuous curvilinear capsulorhexis, the anterior lens capsule was collected, immediately fixed, and processed for electron microscopy analysis. Backscattered electron images of the cross-section of the anterior lens capsule were observed under a scanning electron microscope. The ultrastructure of the anterior lens capsule was observed and compared between the groups. Factors associated with the occurrence of the lamellar structure were also identified, with the presence or absence of a lamellar structure as an objective variable and preoperative clinical characteristics as the explanatory variables. RESULTS 50 eyes of 50 patients were included. In the younger patient group, 20 eyes (80%) had a homogeneous lens capsule, whereas 5 eyes had lamellar structures. By contrast, in the older patient group, 5 eyes had homogeneous structures, while the remaining 20 eyes (80%) had lamellar structures. 1 eye showed capsular delamination. The only significant factor for the occurrence of lamellar structures was age group ( P < .01, nominal logistic regression analysis). CONCLUSIONS Lamellar structures appear in the anterior capsule during aging. The appearance of lamellar structures indicates fragility of the lens capsule, which may, in turn, lead to capsular delamination or lens dislocation in some cases.
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Affiliation(s)
- Akira Hirata
- From the Hayashi Eye Hospital, Fukuoka, Japan (Hirata, Mine, Hayashi); Department of Anatomy, Kurume University School of Medicine, Kurume, Japan (Hirata)
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17
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Glazier AN. Proposed Role for Internal Lens Pressure as an Initiator of Age-Related Lens Protein Aggregation Diseases. Clin Ophthalmol 2022; 16:2329-2340. [PMID: 35924184 PMCID: PMC9342656 DOI: 10.2147/opth.s369676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 07/13/2022] [Indexed: 11/23/2022] Open
Abstract
The process that initiates lens stiffness evident in age-related lens protein aggregation diseases is thought to be mainly the result of oxidation. While oxidation is a major contributor, the exposure of lens proteins to physical stress over time increases susceptibility of lens proteins to oxidative damage, and this is believed to play a significant role in initiating these diseases. Accordingly, an overview of key physical stressors and molecular factors known to be implicated in the development of age-related lens protein aggregation diseases is presented, paying particular attention to the consequence of persistent increase in internal lens pressure.
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Affiliation(s)
- Alan N Glazier
- Optometry, KeplrVision, Rockville, MD, USA
- Correspondence: Alan N Glazier, Email
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18
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Cabeza-Gil I, Calvo B. Predicting the biomechanical stability of IOLs inside the postcataract capsular bag with a finite element model. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 221:106868. [PMID: 35594579 DOI: 10.1016/j.cmpb.2022.106868] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 04/25/2022] [Accepted: 05/07/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND AND OBJECTIVES Although cataract surgery is a safe operation in developed countries, there is still room for improvement in terms of patient satisfaction. One of the key issues is assessing the biomechanical stability of the IOL within the capsular bag to avoid refractive errors that lead to a second surgery. For that purpose, a numerical model was developed to predict IOL position inside the capsular bag in the short- and long-term. METHODS A finite element model containing the implanted IOL, the postcataract capsular bag, the zonules, and a portion of the ciliary body was designed. The C-loop hydrophobic LUCIA IOL was used to validate the numerical model and two more worldwide IOL designs were tested: the double C-loop hydrophobic POD FT IOL and the plate hydrophilic AT LISA IOL. To analyze the biomechanical stability in the long-term, the effect of the fusion footprint, which occurs days following cataract surgery, was simulated. Moreover, several scenarios were analyzed: the size and location of the capsulorexhis, the capsular bag diameter, the initial geometry of the capsular bag, and the material properties of the bag. RESULTS The biomechanical stability of the LUCIA IOL was simulated and successfully compared with the in vitro results. The plate AT LISA design deformed the capsular bag diameter up to 11.0 mm against 10.5 mm for the other designs. This design presented higher axial displacement and lower rotation, 0.19 mm and 0.2∘, than the C-loop design, 0.09 mm and 0.9∘. CONCLUSIONS All optomechanical biomarkers were optimal, assuring good optical performance of the three IOLs under investigation. Our findings showed that the capsulorexhis size influences the stiffness of the capsular bag; however, the shape in the anterior and posterior curvature surfaces of the bag barely affect. The results also suggested that the IOL is prone to mechanical perturbations with the fusion footprint, but they were not high enough to produce a significant refractive error. The proposed model could be a breakthrough in the selection of haptic design according to patient criteria.
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Affiliation(s)
- I Cabeza-Gil
- Aragón Institute of Engineering Research (i3A), University of Zaragoza, Spain.
| | - B Calvo
- Aragón Institute of Engineering Research (i3A), University of Zaragoza, Spain; Centro de Investigación Biomédica en Red en Bioingenieria, Biomateriales y Nanomedicina (CIBER-BBN), Spain
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19
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Osorno LL, Mosley RJ, Poley PL, Bowers J, Gorski G, Gerhart J, Getts R, George-Weinstein M, Byrne ME. Sustained Release of Antibody-Conjugated DNA Nanocarriers from a Novel Injectable Hydrogel for Targeted Cell Depletion to Treat Cataract Posterior Capsule Opacification. J Ocul Pharmacol Ther 2022; 38:404-411. [PMID: 35377237 DOI: 10.1089/jop.2021.0111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Purpose: To compare a novel, sustained release formulation and a bolus injection of a targeted nanocarrier for the ability to specifically deplete cells responsible for the development of posterior capsule opacification (PCO) in week-long, dynamic cell cultures. Methods: A novel, injectable, thermosensitive poly(D,L-lactic-co-glycolic acid)-b-poly(ethylene glycol)-b-poly(D,L-lactic-co-glycolic acid) (PLGA-PEG-PLGA) triblock copolymer hydrogel was engineered for the sustained release of targeted, nucleic acid nanocarriers loaded with cytotoxic doxorubicin (G8:3DNA:Dox). Human rhabdomyosarcoma (RD) cells were used due to their expression of brain-specific angiogenesis inhibitor 1 (BAI1), a specific marker for the myofibroblasts responsible for PCO. Under constant media flow, nanocarriers were injected into cell cultures as either a bolus or within the hydrogel. Cells were fixed and stained every other day for 7 days to compare targeted depletion of BAI1+ cells. Results: The formulation transitions to a gel at physiological temperatures, is optically clear, noncytotoxic, and can release G8:3DNA:Dox nanocarriers for up to 4 weeks. In RD cell cultures, G8:3DNA:Dox nanocarriers specifically eliminated BAI1+ cells. The bolus nanocarrier dose showed significantly reduced cell depletion overtime, while the sustained release of nanocarriers showed increased cell depletion over time. By day 7, <2% of BAI1+ cells were depleted by the bolus injection and 74.2% BAI1+ cells were targeted by the sustained release of nanocarriers. Conclusions: The sustained release of nanocarriers from the hydrogel allows for improved therapeutic delivery in a dynamic system. This method can offer a more effective and efficient method of prophylactically treating PCO after cataract surgery.
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Affiliation(s)
- Laura L Osorno
- Biomimetic and Biohybrid Materials, Biomedical Devices, and Drug Delivery Laboratories, Department of Biomedical Engineering, Rowan University, Glassboro, New Jersey, USA
| | - Robert J Mosley
- Biomimetic and Biohybrid Materials, Biomedical Devices, and Drug Delivery Laboratories, Department of Biomedical Engineering, Rowan University, Glassboro, New Jersey, USA
| | - Patricia L Poley
- Biomimetic and Biohybrid Materials, Biomedical Devices, and Drug Delivery Laboratories, Department of Biomedical Engineering, Rowan University, Glassboro, New Jersey, USA
| | | | - Grzegorz Gorski
- Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania, USA
| | - Jacquelyn Gerhart
- Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania, USA
| | | | | | - Mark E Byrne
- Biomimetic and Biohybrid Materials, Biomedical Devices, and Drug Delivery Laboratories, Department of Biomedical Engineering, Rowan University, Glassboro, New Jersey, USA.,Department of Chemical Engineering, Rowan University, Glassboro, New Jersey, USA.,OcuMedic, Inc., Mullica Hill, New Jersey, USA
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20
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Waring GO, Price FW, Wirta D, McCabe C, Moshirfar M, Guo Q, Gore A, Liu H, Safyan E, Robinson MR. Safety and Efficacy of AGN-190584 in Individuals With Presbyopia: The GEMINI 1 Phase 3 Randomized Clinical Trial. JAMA Ophthalmol 2022; 140:363-371. [PMID: 35238902 PMCID: PMC8895317 DOI: 10.1001/jamaophthalmol.2022.0059] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
IMPORTANCE AGN-190584 (Allergan, an AbbVie company) is an optimized topical formulation of pilocarpine hydrochloride, 1.25%, designed for managing presbyopia and enhanced with a proprietary vehicle. OBJECTIVE To evaluate the efficacy and safety of pilocarpine hydrochloride, 1.25%, in individuals with presbyopia. DESIGN, SETTING, AND PARTICIPANTS This vehicle-controlled, participant- and investigator-masked, randomized, phase 3 clinical study, GEMINI 1, enrolled individuals with presbyopia, aged 40 to 55 years, at 36 sites in the United States from December 21, 2018, to October 31, 2019. Analysis took place between February 2020 and December 2021. INTERVENTIONS AGN-190584 or the AGN-190584 formulation vehicle was administered bilaterally, once daily for 30 days. MAIN OUTCOMES AND MEASURES The proportion of participants with improvement of 3 or more lines in mesopic, high-contrast, binocular distance-corrected near visual acuity (DCNVA) at hours 3 and 6 on day 30 were the primary and key secondary efficacy end points, respectively. Safety measures included adverse events. RESULTS Of 323 participants who were randomized, 235 (72.8%) were female and 292 (90.4%) were White. The mean (SD) age was 49.6 (3.5) years, and the baseline mean (SD) mesopic DCNVA was 29.2 (6.3) letters. A total of 163 individuals were randomized to AGN-190584 and 160 were randomized to vehicle. GEMINI 1 met its primary and key secondary efficacy end points. On day 30, hour 3, the percentage of participants with improvement of 3 or more lines in mesopic DCNVA was 30.7% (50 of 163) in the AGN-190584 group and 8.1% (13 of 160) in the vehicle group (difference, 22.5% [95% CI, 14.3%-30.8%]; adjusted P < .001). At hour 6, those percentages were 18.4% (30 of 163) and 8.8% (14 of 160), respectively (difference, 9.7% [95% CI, 2.3%-17.0%]; adjusted P = .01). At hour 8, the between-group difference in 3 or more lines of mesopic DCNVA gains was not statistically significant, but clinically relevant prespecified outcome measures demonstrated AGN-190584 superiority to vehicle in least-squares mean (SE) mesopic DCNVA change from baseline at hour 8 (5.4 [0.51] vs 3.6 [0.52] letters; P = .009) and photopic distance-corrected intermediate visual acuity at hour 8 (3.9 [0.44] vs 2.4 [0.45] letters; P = .01) and hour 10 (3.5 [0.46] vs 1.7 [0.47] letters; P = .004). No participants with mesopic DCNVA improvement of 3 or more lines at hour 3 had losses of more than 5 letters in mesopic, high-contrast, binocular-corrected distance visual acuity. The onset of effect was at 15 minutes. AGN-190584 demonstrated an acceptable safety and tolerability profile. CONCLUSIONS AND RELEVANCE AGN-190584 demonstrated superiority over vehicle in mesopic DCNVA on day 30, hours 3 and 6, with an acceptable safety profile. AGN-190584 is a safe and efficacious topical therapy for presbyopia through 30 days. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT03804268.
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Affiliation(s)
| | | | - David Wirta
- Eye Research Foundation, Newport Beach, California
| | | | - Majid Moshirfar
- Hoopes Vision Research Center, Draper, Utah,John A. Moran Eye Center, University of Utah, Salt Lake City
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21
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Bailey MHJ, Wilson M. Simulation of defects, flexibility and rupture in biopolymer networks. RSC Adv 2022; 12:2171-2180. [PMID: 35425240 PMCID: PMC8979039 DOI: 10.1039/d1ra07262e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 12/14/2021] [Indexed: 11/30/2022] Open
Abstract
Networks of biopolymers occur often in nature, and are vulnerable to damage over time. In this work, a coarse grained model of collagen IV molecules is applied in a 2D hexagonal network and the mechanisms by which these networks can rupture are explored. The networks are stretched linearly in order to study their structural limits and mechanism of rupture over timescale of up to 100 μs. Metrics are developed to track the damage networks suffer over time, and qualitatively analyse ruptures that occur. Further simulations repeatedly stretch the networks sinusoidally to mimic the in vivo strains. Defects of increasing levels of complexity are introduced into an ordered network, and their effect on the rupturing behaviour of the biopolymer networks studied. The effect of introducing holes of varying size in the network, as well as strips of finite width to mimic surgical damage are studied. These demonstrate the importance of the flexibility of the networks to preventing damage. We use a coarse grained polymer model and a simple graph representation to introduce defects into a biopolymer network, then cause them to rupture.![]()
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Affiliation(s)
- Matthew H J Bailey
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford South Parks Road Oxford OX1 3QZ UK
| | - Mark Wilson
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford South Parks Road Oxford OX1 3QZ UK
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22
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Avetisov SE, Shitikova AV, Avetisov KS. [Anatomical, morphological and biomechanical aspects of accommodation]. Vestn Oftalmol 2022; 138:117-125. [PMID: 36004600 DOI: 10.17116/oftalma2022138041117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The article reviews the findings on the anatomy, morphological and biomechanical features of the accommodation apparatus. Modern methods of imaging and biometry confirm the validity of the Helmholtz lenticular theory of accommodation, according to which its mechanism involves three main components: the ciliary body, the zonular fibres and the lens capsule, the lens itself. Based on this, there is certain interest in studying the degree of participation of each of these components in the development of age-related changes in accommodation (presbyopia).
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Affiliation(s)
- S E Avetisov
- Research Institute of Eye Disease, Moscow, Russia
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
| | | | - K S Avetisov
- Research Institute of Eye Disease, Moscow, Russia
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23
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Characterisation and Modelling of an Artificial Lens Capsule Mimicking Accommodation of Human Eyes. Polymers (Basel) 2021; 13:polym13223916. [PMID: 34833214 PMCID: PMC8619262 DOI: 10.3390/polym13223916] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/29/2021] [Accepted: 11/03/2021] [Indexed: 11/17/2022] Open
Abstract
A synthetic material of silicone rubber was used to construct an artificial lens capsule (ALC) in order to replicate the biomechanical behaviour of human lens capsule. The silicone rubber was characterised by monotonic and cyclic mechanical tests to reveal its hyper-elastic behaviour under uniaxial tension and simple shear as well as the rate independence. A hyper-elastic constitutive model was calibrated by the testing data and incorporated into finite element analysis (FEA). An experimental setup to simulate eye focusing (accommodation) of ALC was performed to validate the FEA model by evaluating the shape change and reaction force. The characterisation and modelling approach provided an insight into the intrinsic behaviour of materials, addressing the inflating pressure and effective stretch of ALC under the focusing process. The proposed methodology offers a virtual testing environment mimicking human capsules for the variability of dimension and stiffness, which will facilitate the verification of new ophthalmic prototype such as accommodating intraocular lenses (AIOLs).
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24
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Wei H, Wolffsohn JS, Gomes de Oliveira O, Davies LN. An Artificial Lens Capsule with a Lens Radial Stretching System Mimicking Dynamic Eye Focusing. Polymers (Basel) 2021; 13:polym13203552. [PMID: 34685312 PMCID: PMC8540979 DOI: 10.3390/polym13203552] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/08/2021] [Accepted: 10/09/2021] [Indexed: 11/17/2022] Open
Abstract
Presbyopia is a common eye disorder among aged people which is attributed to the loss of accommodation of the crystalline lens due to the increasing stiffness. One of the potential techniques to correct presbyopia involves removing the lens substance inside the capsule and replacing it with an artificial lens. The development of such devices, e.g., accommodating intraocular lenses (AIOLs), relies on the understanding of the biomechanical behaviour of the lens capsule and the essential design verification ex vivo. To mimic the eye’s dynamic focusing ability (accommodation), an artificial lens capsule (ALC), from silicone rubber accompanied by a lens radial stretching system (LRSS) was developed. The ALC was manufactured to offer a dimension and deforming behaviour replicating the human lens capsule. The LRSS was calibrated to provide a radial stretch simulating the change of diameter of capsules during accommodating process. The biomechanical function of the ALC was addressed by studying its evolution behaviour and reaction force under multiaxial stretch from the LRSS. The study highlighted the convenience of this application by performing preliminary tests on prototypes of ophthalmic devices (e.g., AIOLs) to restore accommodation.
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Affiliation(s)
- Huidong Wei
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK;
- Rayner Intraocular Lenses Limited, Worthing BN14 8AQ, UK;
- Correspondence: (H.W.); (J.S.W.); Tel.: +44-(0)121-204-4140 (J.S.W.)
| | - James S. Wolffsohn
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK;
- Correspondence: (H.W.); (J.S.W.); Tel.: +44-(0)121-204-4140 (J.S.W.)
| | | | - Leon N. Davies
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK;
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25
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Cabeza-Gil I, Grasa J, Calvo B. A validated finite element model to reproduce Helmholtz's theory of accommodation: a powerful tool to investigate presbyopia. Ophthalmic Physiol Opt 2021; 41:1241-1253. [PMID: 34463367 DOI: 10.1111/opo.12876] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 07/15/2021] [Accepted: 07/16/2021] [Indexed: 12/20/2022]
Abstract
PURPOSE To reproduce human in vivo accommodation numerically. For that purpose, a finite element model specific for a 29-year-old subject was designed. Once the proposed numerical model was validated, the decrease in accommodative amplitude with age was simulated according to data available in the literature. METHODS In contrast with previous studies, the non-accommodated eye condition was the reference configuration. Consequently, two aspects were specifically highlighted: contraction of the ciliary muscle, which was simulated by a continuum electro-mechanical model and incorporation of initial lens capsule stresses, which allowed the lens to become accommodated after releasing the resting zonular tension. RESULTS The morphological changes and contraction of the ciliary muscle were calibrated accurately according to the experimental data from the literature. All dynamic optical and biometric lens measurements validated the model. With the proposed numerical model, presbyopia was successfully simulated. CONCLUSIONS The most widespread theory of accommodation, proposed by Helmholtz, was simulated accurately. Assuming the same initial stresses in the lens capsule over time, stiffening of the lens nucleus is the main cause of presbyopia.
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Affiliation(s)
- Iulen Cabeza-Gil
- Aragόn Institute of Engineering Research (i3A), University of Zaragoza, Zaragoza, Spain
| | - Jorge Grasa
- Aragόn Institute of Engineering Research (i3A), University of Zaragoza, Zaragoza, Spain.,Bioengineering, Biomaterials and Nanomedicine Networking Biomedical Research Centre (CIBER-BBN), Zaragoza, Spain
| | - Begoña Calvo
- Aragόn Institute of Engineering Research (i3A), University of Zaragoza, Zaragoza, Spain.,Bioengineering, Biomaterials and Nanomedicine Networking Biomedical Research Centre (CIBER-BBN), Zaragoza, Spain
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A numerical investigation of changes in lens shape during accommodation. Sci Rep 2021; 11:9639. [PMID: 33953252 PMCID: PMC8100116 DOI: 10.1038/s41598-021-89145-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/22/2021] [Indexed: 12/25/2022] Open
Abstract
The purpose of this study was to investigate how the mechanical properties and geometry of the lens influence the changes in lens shape during accommodation. To do so, ex vivo stretching tests of the isolated lens were simulated via finite element analysis. In these tests, the lens is stretched from the accommodated state to the non-accommodated state. Several key characteristics of the lens were studied: the stiffness gradient of the lens material, the distribution of the capsule thickness, the mechanical properties of the capsule and the material comprising the lens, nucleus and cortex, and the influence of two different age-related lens geometries (17 and 29 y/o subjects). To determine the effects on the changes in lens shape during accommodation, changes in the anterior and posterior radius, the lens and nucleus thicknesses and the equatorial lens diameter were analysed. The results suggest that multiple factors exert statistically significant influences on how the lens changes its shape, but two factors predominate over the rest: the stiffness ratio between the nucleus and cortex and the stiffness of the capsule, specifically the posterior surface.
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Huang D, Xu C, Guo R, Ji J, Liu W. Anterior lens capsule: biomechanical properties and biomedical engineering perspectives. Acta Ophthalmol 2021; 99:e302-e309. [PMID: 32914585 DOI: 10.1111/aos.14600] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 07/19/2020] [Accepted: 08/01/2020] [Indexed: 12/13/2022]
Abstract
Anterior lens capsule, as the thickest basement membrane in the body, has its unique physiology characteristics. In ophthalmology, many attempts have been made to culture different kinds of cells including iris pigment epithelial cells, retinal pigment epithelial cells, corneal epithelium and endothelium cells, trabecular meshwork cells etc and anterior lens capsule has been confirmed to be served as an excellent scaffold for the growth and expansion of different ocular cells. Furthermore, anterior lens capsule also has unique potential in gestation evaluation and the treatment of various ocular diseases, including corneal ulcer, glaucoma, age-related macular degeneration and macular hole, etc. Here, we provide an overview of the biomechanical properties and biomedical engineering perspectives of anterior lens capsule.
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Affiliation(s)
- Dandan Huang
- Department of Ophthalmology Taihe Hospital Hubei University of Medicine Shiyan China
| | - Chenjia Xu
- Tianjin Key Laboratory of Retinal Functions and Diseases Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science Eye Institute and School of Optometry Tianjin Medical University Eye Hospital Tianjin China
| | - Ruru Guo
- Tianjin Key Laboratory of Retinal Functions and Diseases Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science Eye Institute and School of Optometry Tianjin Medical University Eye Hospital Tianjin China
| | - Jian Ji
- Tianjin Key Laboratory of Retinal Functions and Diseases Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science Eye Institute and School of Optometry Tianjin Medical University Eye Hospital Tianjin China
| | - Wei Liu
- Tianjin Key Laboratory of Retinal Functions and Diseases Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science Eye Institute and School of Optometry Tianjin Medical University Eye Hospital Tianjin China
- Department of Ophthalmology University Medical Center Groningen University of Groningen Groningen The Netherlands
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28
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Ramos-Martínez I, Vivanco-Rojas O, Juárez-Domínguez B, Hernández-Zimbrón L, Ochoa-de la Paz L, Quiroz-Mercado H, Ramírez-Hernández E, Gulias-Cañizo R, Zenteno E. Abnormal N-Glycosylation of Human Lens Epithelial Cells in Type-2 Diabetes May Contribute to Cataract Progression. Clin Ophthalmol 2021; 15:1365-1373. [PMID: 33833495 PMCID: PMC8020457 DOI: 10.2147/opth.s300242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Accepted: 03/04/2021] [Indexed: 12/17/2022] Open
Abstract
Purpose In order to better understand cataract development, we analyzed the glycosylation profile of human lens epithelial cells (HLECs) from anterior lens capsules of type 2 diabetes mellitus (T2DM) and non-diabetic (ND) patients undergoing routine cataract surgery. Setting Research Department of the Asociación para Evitar la Ceguera, Hospital "Dr. Luis Sánchez Bulnes", Mexico. Design Experimental study. Methods Evaluation of anterior lens capsules from T2DM and ND patients undergoing phacoemulsification and free from other ocular diseases. Results Hematoxylin-eosin staining revealed HLECs alterations in T2DM samples. From lectins with different sugar specificities used, concanavalin A showed significant differences, labeling homogeneously both in the cytoplasm and in cell membranes in ND capsules, while in T2DM capsules, in addition to membrane and cytoplasm labeling, there were perinuclear vesicles with high concanavalin A labeling. Two-dimensional gel electrophoresis showed that T2DM patients have a ~65-kDa spot with an isoelectric point of 5.5 with a higher density compared to ND capsules, and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis showed 62% homology with type-1 cytokeratin. Immunohistochemistry using anti-pan cytokeratin antibody revealed co-localization with concanavalin A, and a lectin blot revealed with concanavalin A showed a band of ~65 kDa, a molecular weight that corresponds to human type 1 cytokeratin. Conclusion These results suggest that over-expression of N-glycosidically linked human type 1 cytokeratin may induce capsule disruption and affect selective permeability, allowing the entry of different molecules to the lens that facilitate cataract progression.
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Affiliation(s)
- Ivan Ramos-Martínez
- Departamento de Bioquímica, Facultad de Medicina UNAM, Ciudad de Mexico, 04510, Mexico.,Departamento de Investigación, Asociación para Evitar la Ceguera en Mexico I.A.P. Hospital Dr. Luis Sánchez Bulnes, Mexico City, Mexico.,Glycobiology, Cell Growth and Tissue Repair Research Unit (Gly-CRRET), Université Paris Est Créteil (UPEC), Créteil, France
| | - Oscar Vivanco-Rojas
- Departamento de Investigación, Asociación para Evitar la Ceguera en Mexico I.A.P. Hospital Dr. Luis Sánchez Bulnes, Mexico City, Mexico
| | - Brenda Juárez-Domínguez
- Departamento de Investigación, Asociación para Evitar la Ceguera en Mexico I.A.P. Hospital Dr. Luis Sánchez Bulnes, Mexico City, Mexico
| | - Luis Hernández-Zimbrón
- Departamento de Bioquímica, Facultad de Medicina UNAM, Ciudad de Mexico, 04510, Mexico.,Departamento de Investigación, Asociación para Evitar la Ceguera en Mexico I.A.P. Hospital Dr. Luis Sánchez Bulnes, Mexico City, Mexico
| | - Lenin Ochoa-de la Paz
- Departamento de Bioquímica, Facultad de Medicina UNAM, Ciudad de Mexico, 04510, Mexico.,Departamento de Investigación, Asociación para Evitar la Ceguera en Mexico I.A.P. Hospital Dr. Luis Sánchez Bulnes, Mexico City, Mexico
| | - Hugo Quiroz-Mercado
- Departamento de Investigación, Asociación para Evitar la Ceguera en Mexico I.A.P. Hospital Dr. Luis Sánchez Bulnes, Mexico City, Mexico
| | | | - Rosario Gulias-Cañizo
- Centro de Investigación en Ciencias de la Salud (CICSA), Universidad Anáhuac Mexico, Huixquilucan, Estado de Mexico, Mexico
| | - Edgar Zenteno
- Departamento de Bioquímica, Facultad de Medicina UNAM, Ciudad de Mexico, 04510, Mexico.,Departamento de Investigación, Asociación para Evitar la Ceguera en Mexico I.A.P. Hospital Dr. Luis Sánchez Bulnes, Mexico City, Mexico
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29
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Knaus KR, Hipsley A, Blemker SS. The action of ciliary muscle contraction on accommodation of the lens explored with a 3D model. Biomech Model Mechanobiol 2021; 20:879-894. [PMID: 33491156 DOI: 10.1007/s10237-021-01417-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 01/04/2021] [Indexed: 11/24/2022]
Abstract
The eye's accommodative mechanism changes optical power for near vision. In accommodation, ciliary muscle excursion relieves lens tension, allowing it to return to its more convex shape. Lens deformation alters its refractive properties, but the mechanics of ciliary muscle actions are difficult to intuit due to the complex architecture of the tissues involved. The muscle itself comprises three sections of dissimilarly oriented cells. These cells contract, transmitting forces through the zonule fibers and extralenticular structures. This study aims to create a finite element model (FEM) to predict how the action of the ciliary muscle sections leads to lens displacement. The FEM incorporates initialization of the disaccommodated lens state and ciliary muscle contraction, with three muscle sections capable of independent activation, to drive accommodative movement. Model inputs were calibrated to replicate experimentally measured disaccommodated lens and accommodated ciliary muscle shape changes. Additional imaging studies were used to validate model predictions of accommodative lens deformation. Models were analyzed to quantify mechanical actions of ciliary muscle sections in lens deformation and position modulation. Analyses revealed that ciliary muscle sections act synergistically: the circular section contributes most to increasing lens thickness, while longitudinal and radial sections can oppose this action. Conversely, longitudinal and radial sections act to translate the lens anteriorly with opposition from the circular section. This FEM demonstrates the complex interplay of the three sections of ciliary muscle in deforming and translating the lens during accommodation, providing a useful framework for future investigations of accommodative dysfunction that occurs with age in presbyopia.
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Affiliation(s)
- Katherine R Knaus
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | | | - Silvia S Blemker
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA. .,Department of Mechanical Engineering, University of Virginia, Charlottesville, VA, USA. .,Department of Orthopedic Surgery, University of Virginia, Charlottesville, VA, USA. .,Department of Ophthalmology, University of Virginia, 415 Lane Road, Box 800759, Charlottesville, VA, 22903, USA.
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30
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Karayilan M, Clamen L, Becker ML. Polymeric Materials for Eye Surface and Intraocular Applications. Biomacromolecules 2021; 22:223-261. [PMID: 33405900 DOI: 10.1021/acs.biomac.0c01525] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ocular applications of polymeric materials have been widely investigated for medical diagnostics, treatment, and vision improvement. The human eye is a vital organ that connects us to the outside world so when the eye is injured, infected, or impaired, it needs immediate medical treatment to maintain clear vision and quality of life. Moreover, several essential parts of the eye lose their functions upon aging, causing diminished vision. Modern polymer science and polymeric materials offer various alternatives, such as corneal and scleral implants, artificial ocular lenses, and vitreous substitutes, to replace the damaged parts of the eye. In addition to the use of polymers for medical treatment, polymeric contact lenses can provide not only vision correction, but they can also be used as wearable electronics. In this Review, we highlight the evolution of polymeric materials for specific ocular applications such as intraocular lenses and current state-of-the-art polymeric systems with unique properties for contact lens, corneal, scleral, and vitreous body applications. We organize this Review paper by following the path of light as it travels through the eye. Starting from the outside of the eye (contact lenses), we move onto the eye's surface (cornea and sclera) and conclude with intraocular applications (intraocular lens and vitreous body) of mostly synthetic polymers and several biopolymers. Initially, we briefly describe the anatomy and physiology of the eye as a reminder of the eye parts and their functions. The rest of the Review provides an overview of recent advancements in next-generation contact lenses and contact lens sensors, corneal and scleral implants, solid and injectable intraocular lenses, and artificial vitreous body. Current limitations for future improvements are also briefly discussed.
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Affiliation(s)
- Metin Karayilan
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Liane Clamen
- Adaptilens, LLC, Boston, Massachusetts 02467, United States
| | - Matthew L Becker
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States.,Mechanical Engineering and Materials Science, Orthopaedic Surgery, and Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
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31
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Berggren CC, Ameku KA, Pedrigi RM. Altered stress field of the human lens capsule after cataract surgery. J Biomech 2020; 115:110127. [PMID: 33223144 DOI: 10.1016/j.jbiomech.2020.110127] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 10/16/2020] [Accepted: 11/04/2020] [Indexed: 10/23/2022]
Abstract
The lens capsule of the eye is important in focusing light onto the retina during the process of accommodation and, in later life, housing a prosthetic lens implanted during cataract surgery. Though considerable modeling work has characterized the mechanics of accommodation, little has been done to understand the mechanics of the lens capsule after cataract surgery. As such, we present the first 3-D finite element model of the post-surgical human lens capsule with an implanted tension ring and, separately, an intraocular lens to characterize the altered stress field compared to that in a model of the native lens capsule. All finite element models employed a Holzapfel hyperelastic constitutive model with regional variations in anisotropy. The post-surgical lens capsule demonstrated a dramatic perturbation to the stress field with mostly large reductions in stresses (except at the equator where the implant contacts the capsule) compared to native, wherein maximal changes in Cauchy stress were -100% and -145% for the tension ring and intraocular lens, respectively. However, implantation of the tension ring produced a more uniform stress field compared to the IOL. The magnitudes and distribution of the perturbed stress field may be an important driver of the fibrotic response of inhabiting lens epithelial cells and associated lens capsule remodeling after cataract surgery. Thus, the mechanical effects of an implant on the lens capsule could be an essential consideration in the design of intraocular lenses, particularly those with an accommodative feature.
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Affiliation(s)
- Caleb C Berggren
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, United States
| | - Kurt A Ameku
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, United States
| | - Ryan M Pedrigi
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, United States.
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32
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Efremov YM, Bakhchieva NA, Shavkuta BS, Frolova AA, Kotova SL, Novikov IA, Akovantseva AA, Avetisov KS, Avetisov SE, Timashev PS. Mechanical properties of anterior lens capsule assessed with AFM and nanoindenter in relation to human aging, pseudoexfoliation syndrome, and trypan blue staining. J Mech Behav Biomed Mater 2020; 112:104081. [PMID: 32961392 DOI: 10.1016/j.jmbbm.2020.104081] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 08/05/2020] [Accepted: 09/05/2020] [Indexed: 01/05/2023]
Abstract
The purpose of this study is the mechanical characterization of the mid-to- old-age human anterior lens capsules (ALCs) obtained by capsulorhexis using Atomic Force Microscopy (AFM) and a nanoindenter at different spatial scales. The dependencies on the human age, presence or absence of pseudoexfoliation syndrome (PEX), and application of trypan blue staining during the surgery were analyzed. The measurements on both the anterior (AS) and epithelial (ES) sides of the ALC were conducted and the effect of cells present on the epithelial side was carefully accounted for. The ES of the ALC had a homogenous distribution of the Young's modulus over the surface as shown by the macroscale mapping with the nanoindenter and local AFM indentations, while the AS was more heterogeneous. Age-related changes were assessed in groups ranging from the mid-age (from 48 years) to old-age (up to 93 years). We found that the ES was always stiffer than the AS, and this difference decreased with age due to a gradual decrease in the Young's modulus of the ES and an increase in the modulus of the AS. No significant changes were found in the mechanical properties of ALCs of PEX patients versus the PEX-free group, as well as in the properties of the ALC with and without trypan blue staining.
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Affiliation(s)
- Yuri M Efremov
- Institute for Regenerative Medicine, Sechenov University, 8 Trubetskaya St., Moscow, 119991, Russia.
| | | | - Boris S Shavkuta
- Institute for Regenerative Medicine, Sechenov University, 8 Trubetskaya St., Moscow, 119991, Russia; Institute of Photon Technologies of Federal Scientific Research Centre "Crystallography and Photonics" of Russian Academy of Sciences, Pionerskaya 2, Troitsk, Moscow, 108840, Russia
| | - Anastasia A Frolova
- Institute for Regenerative Medicine, Sechenov University, 8 Trubetskaya St., Moscow, 119991, Russia
| | - Svetlana L Kotova
- Institute for Regenerative Medicine, Sechenov University, 8 Trubetskaya St., Moscow, 119991, Russia; N.N. Semenov Institute of Chemical Physics, 4 Kosygin St., Moscow, 119991, Russia
| | - Ivan A Novikov
- Research Institute of Eye Diseases, 11 Rossolimo St., Moscow, 119021, Russia
| | - Anastasia A Akovantseva
- Institute for Regenerative Medicine, Sechenov University, 8 Trubetskaya St., Moscow, 119991, Russia
| | | | - Sergei E Avetisov
- Research Institute of Eye Diseases, 11 Rossolimo St., Moscow, 119021, Russia; Sechenov University, 2 Bol'shaya Pirogovskaya St., Bldg.4, Moscow, 119991, Russia
| | - Peter S Timashev
- Institute for Regenerative Medicine, Sechenov University, 8 Trubetskaya St., Moscow, 119991, Russia; Institute of Photon Technologies of Federal Scientific Research Centre "Crystallography and Photonics" of Russian Academy of Sciences, Pionerskaya 2, Troitsk, Moscow, 108840, Russia; N.N. Semenov Institute of Chemical Physics, 4 Kosygin St., Moscow, 119991, Russia; Chemistry Department, Lomonosov Moscow State University, Leninskiye Gory 1-3, Moscow, 119991, Russia
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33
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Advances in the Study of Lens Refilling. J Ophthalmol 2020; 2020:8956275. [PMID: 32908687 PMCID: PMC7471792 DOI: 10.1155/2020/8956275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 07/22/2020] [Accepted: 07/29/2020] [Indexed: 12/03/2022] Open
Abstract
The ultimate goal of cataract surgery is to restore the accommodation while restoring distance visual acuity. Different kinds of accommodative intraocular lens (IOLs) and surgical techniques have been suggested to apply during the surgery, but they showed poor postoperative accommodation. It is possible to achieve this goal by refilling the lens with an injectable polymer. We present a summary of the existing materials, methods, results, and some obstacles in clinical application that remain of lens refilling for restoration of accommodation. Two main problems have restricted the clinical application of this technique. One was the formation of postoperative secondary capsule opacification and the other was the different accommodative power after surgery.
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34
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Avetisov K, Bakhchieva N, Avetisov S, Novikov I, Frolova A, Akovantseva A, Efremov Y, Kotova S, Timashev P. Biomechanical properties of the lens capsule: A review. J Mech Behav Biomed Mater 2020; 103:103600. [DOI: 10.1016/j.jmbbm.2019.103600] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 11/26/2019] [Accepted: 12/13/2019] [Indexed: 10/25/2022]
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35
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Tekin K, Ozdamar Erol Y, Inanc M, Sargon MF, Cakar Ozdal P, Berker N. Ultrastructural Analysis of the Anterior Lens Epithelium in Cataracts Associated with Uveitis. Ophthalmic Res 2019; 63:213-221. [PMID: 31838467 DOI: 10.1159/000504497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 10/31/2019] [Indexed: 12/14/2022]
Abstract
PURPOSE To investigate the transmission electron microscopic findings of lens epithelial cells (LECs) in patients with different subtypes of uveitis and to compare the findings with those in age-matched controls. METHODS In this prospective case-control study, the anterior lens capsules were taken from 47 eyes of 47 patients with uveitis of different subtypes (17 with Fuchs uveitis syndrome [FUS], 13 with -Behçet's uveitis, 10 with idiopathic uveitis, and 7 with herpetic keratouveitis) and from 15 eyes of 15 control patients. RESULTS In the FUS group, the LECs had homogeneous thickening and irregularity, with some small vacuoles and widespread, oval-shaped pigment clusters in some areas. In the Behçet uveitis group, there was evident thinning in the lens epithelium. The subepithelial tissue under the epithelium was thickened, and edematous areas were detected. In the idiopathic uveitis group, the LECs were thinner with small vacuoles, and the cubic structure of the LECs was transformed into a squamous one. Moreover, the LECs included some small vacuoles, similar to those in the FUS group. In the herpetic keratouveitis group, two prominent cell types were observed: (1) completely normal LECs and (2) degenerated-type LECs with pyknotic nuclei, condensation of chromatin, swelling in the cytoplasm, membrane ruptures, and intra-cytoplasmic inclusion bodies. In the control group, the LECs and all of their elements occurred in normal ultrastructural patterns, with the exception of a few small intraepithelial vacuoles, which were fewer in number and smaller than those in the FUS and idiopathic uveitis groups. CONCLUSION The electron microscopic analysis of LECs of patients with different subtypes of uveitis revealed significant ultrastructural alterations, which may be related to the summation of oxidative stress and intraocular inflammation.
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Affiliation(s)
- Kemal Tekin
- Ophthalmology Department, Ercis State Hospital, Van, Turkey,
| | - Yasemin Ozdamar Erol
- Ophthalmology Department, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
| | - Merve Inanc
- Ophthalmology Department, Ercis State Hospital, Van, Turkey
| | | | - Pinar Cakar Ozdal
- Ophthalmology Department, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
| | - Nilufer Berker
- Ophthalmology Department, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
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36
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Sheiko SS, Dobrynin AV. Architectural Code for Rubber Elasticity: From Supersoft to Superfirm Materials. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b01127] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Sergei S. Sheiko
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Andrey V. Dobrynin
- Department of Polymer Science, University of Akron, Akron, Ohio 44325-3909, United States
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37
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Wang K, Pierscionek BK. Biomechanics of the human lens and accommodative system: Functional relevance to physiological states. Prog Retin Eye Res 2019; 71:114-131. [DOI: 10.1016/j.preteyeres.2018.11.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 09/24/2018] [Accepted: 11/07/2018] [Indexed: 12/28/2022]
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38
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Wang K, Hoshino M, Uesugi K, Yagi N, Pierscionek BK. Contributions of shape and stiffness to accommodative loss in the ageing human lens: a finite element model assessment. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2019; 36:B116-B122. [PMID: 31044989 DOI: 10.1364/josaa.36.00b116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 03/06/2019] [Indexed: 06/09/2023]
Abstract
Ageing changes to the various components of the accommodative system of the eye lens contribute to the loss of focusing power. The relative contributions of each ageing component, however, are not well defined. This study investigates the contribution of geometric parameters and material properties on accommodation, simulated using models based on human lenses aged 16, 35, and 48 years. Each model was tested using two different sets of material properties and a range of zonular fiber angles and was compared to results from in vivo measurements. The geometries and material parameters of older and younger lens models were interchanged to investigate the role of shape and material on accommodative capacity. Results indicate that geometry has the greater role in accommodation.
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39
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Vatankhah-Varnosfaderani M, Keith AN, Cong Y, Liang H, Rosenthal M, Sztucki M, Clair C, Magonov S, Ivanov DA, Dobrynin AV, Sheiko SS. Chameleon-like elastomers with molecularly encoded strain-adaptive stiffening and coloration. Science 2018; 359:1509-1513. [PMID: 29599240 DOI: 10.1126/science.aar5308] [Citation(s) in RCA: 224] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Accepted: 01/30/2018] [Indexed: 12/19/2022]
Abstract
Active camouflage is widely recognized as a soft-tissue feature, and yet the ability to integrate adaptive coloration and tissuelike mechanical properties into synthetic materials remains elusive. We provide a solution to this problem by uniting these functions in moldable elastomers through the self-assembly of linear-bottlebrush-linear triblock copolymers. Microphase separation of the architecturally distinct blocks results in physically cross-linked networks that display vibrant color, extreme softness, and intense strain stiffening on par with that of skin tissue. Each of these functional properties is regulated by the structure of one macromolecule, without the need for chemical cross-linking or additives. These materials remain stable under conditions characteristic of internal bodily environments and under ambient conditions, neither swelling in bodily fluids nor drying when exposed to air.
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Affiliation(s)
| | - Andrew N Keith
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Yidan Cong
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Heyi Liang
- Department of Polymer Science, University of Akron, Akron, OH, 44325-3909, USA
| | - Martin Rosenthal
- European Synchrotron Radiation Facility, F-38043 Grenoble, France
| | - Michael Sztucki
- European Synchrotron Radiation Facility, F-38043 Grenoble, France
| | - Charles Clair
- Université de Haute Alsace, Laboratoire de Physique et Mécanique Textiles, F-68093 Mulhouse Cedex, France
| | - Sergei Magonov
- Scanning Probe Microscopy (SPM) Labs, Tempe, AZ 85283, USA
| | - Dimitri A Ivanov
- Institut de Sciences des Matériaux de Mulhouse-IS2M, CNRS UMR 7361, F-68057 Mulhouse, France.,Lomonosov Moscow State University, Faculty of Fundamental Physical and Chemical Engineering, Leninskie Gory 1/51, 119991 Moscow, Russian Federation
| | - Andrey V Dobrynin
- Department of Polymer Science, University of Akron, Akron, OH, 44325-3909, USA.
| | - Sergei S Sheiko
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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40
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Matrix-bound AGEs enhance TGFβ2-mediated mesenchymal transition of lens epithelial cells via the noncanonical pathway: implications for secondary cataract formation. Biochem J 2018; 475:1427-1440. [PMID: 29588342 DOI: 10.1042/bcj20170856] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 03/19/2018] [Accepted: 03/27/2018] [Indexed: 12/28/2022]
Abstract
Advanced glycation end products (AGEs) are post-translational modifications formed from the reaction of reactive carbonyl compounds with amino groups in proteins. Our laboratory has previously shown that AGEs in extracellular matrix (ECM) proteins promote TGFβ2 (transforming growth factor-beta 2)-mediated epithelial-to-mesenchymal transition (EMT) of lens epithelial cells (LECs), which could play a role in fibrosis associated with posterior capsule opacification. We have also shown that αB-crystallin plays an important role in TGFβ2-mediated EMT of LECs. Here, we investigated the signaling mechanisms by which ECM-AGEs enhance TGFβ2-mediated EMT in LECs. We found that in LECs cultured on AGE-modified basement protein extract (AGE-BME), TGFβ2 treatment up-regulated the mesenchymal markers α-SMA (α-smooth muscle actin) and αB-crystallin and down-regulated the epithelial marker E-cadherin more than LECs cultured on unmodified BME and treated with TGFβ2. Using a Multiplex Assay, we found that AGE-BME significantly up-regulated the noncanonical pathway by promoting phosphorylation of ERK (extracellular signal-regulated kinases), AKT, and p38 MAPK (mitogen-activated protein kinases) during TGFβ2-mediated EMT. This EMT response was strongly suppressed by inhibition of AKT and p38 MAPK phosphorylation. The AKT inhibitor LY294002 also suppressed TGFβ2-induced up-regulation of nuclear Snail and reduced phosphorylation of GSK3β. Inhibition of Snail expression suppressed TGFβ2-mediated α-SMA expression. αB-Crystallin was up-regulated in an AKT-dependent manner during AGE-BME/TGFβ2-mediated EMT in LECs. The absence of αB-crystallin in LECs suppressed TGFβ2-induced GSK3β phosphorylation, resulting in lower Snail levels. Taken together, these results show that ECM-AGEs enhance the TGFβ2-mediated EMT response through activation of the AKT/Snail pathway, in which αB-crystallin plays an important role as a linker between the TGFβ2 and AGE-mediated signaling pathways.
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Tekin K, Erol YO, Sargon MF, Inanc M, Ozdal PC, Berker N. Effects of Fuchs uveitis syndrome on the ultrastructure of the anterior lens epithelium: A transmission electron microscopic study. Indian J Ophthalmol 2017; 65:1459-1464. [PMID: 29208835 PMCID: PMC5742983 DOI: 10.4103/ijo.ijo_691_17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
PURPOSE The purpose of the study was to investigate the electron microscopic findings of the lens epithelial cells (LECs) in patients with Fuchs uveitis syndrome (FUS) who suffered from cataracts and to compare those with age-matched controls. METHODS This study was a prospective, comparative case series. The anterior lens capsules (ALC: basement membrane and associated LECs) were taken from 12 eyes of 12 cases of FUS and ten eyes of ten control patients. The ALCs were obtained from cataract surgery and prepared for transmission electron microscopy (TEM). RESULTS There were no statistically significant differences regarding the age or gender between the FUS group and the control group (P > 0.05). In the TEM examinations of the ALCs, all of the FUS cases revealed similar significant ultrastructural changes when compared to the control patients. In the FUS group, the LECs showed homogeneous thickening and irregularity which included some small vacuoles in different areas of the epithelial tissue. Moreover, in some areas of the LECs, widespread, oval-shaped, pigment clusters were detected. Conversely, in the control group, the LECs and all of their elements were in normal ultrastructural patterns, with the exception of some small intraepithelial vacuoles which were fewer and smaller than those in the FUS group. CONCLUSION Ultrastructural analysis of the ALC of the patients with FUS disclosed some significant alterations which may be related to the summation of oxidative stress, intraocular inflammation, and iris atrophy.
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Affiliation(s)
- Kemal Tekin
- Department of Ophthalmology, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
| | - Yasemin Ozdamar Erol
- Department of Ophthalmology, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
| | | | - Merve Inanc
- Department of Ophthalmology, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
| | - Pinar Cakar Ozdal
- Department of Ophthalmology, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
| | - Nilufer Berker
- Department of Ophthalmology, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
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Anterior lens capsule strains during simulated accommodation in porcine eyes. Exp Eye Res 2017; 168:19-27. [PMID: 29288023 DOI: 10.1016/j.exer.2017.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 12/02/2017] [Accepted: 12/22/2017] [Indexed: 11/20/2022]
Abstract
Experimental protocols have been developed to measure the spatial variation of the mechanical strains induced in the lens capsule during ex vivo lens stretching. The paper describes the application of these protocols to porcine lenses. The deformations and mechanical strains developed in the anterior capsule during each experiment were determined using full field digital image correlation techniques, by means of a speckle pattern applied to the lens surface. Several speckling techniques and illumination methods were assessed before a suitable combination was found. Additional data on the cross section shape of the anterior lens surface were obtained by Scheimpflug photography, to provide a means of correcting for lens curvature effects in the determination of the strains developed in the plane of the capsule. The capsule strains in porcine lenses exhibit non-linear behaviour, and hysteresis during loading and unloading. Peripheral regions experience higher magnitude strains than regions near the lens pole. The paper demonstrates the successful application of a procedure to make direct measurements of capsule strains simultaneously with ex vivo radial lens stretching. This experimental technique is applicable to future investigations on the mechanical characteristics of human lenses.
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Kirby MA, Pelivanov I, Song S, Ambrozinski Ł, Yoon SJ, Gao L, Li D, Shen TT, Wang RK, O’Donnell M. Optical coherence elastography in ophthalmology. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-28. [PMID: 29275544 PMCID: PMC5745712 DOI: 10.1117/1.jbo.22.12.121720] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 12/14/2017] [Indexed: 05/03/2023]
Abstract
Optical coherence elastography (OCE) can provide clinically valuable information based on local measurements of tissue stiffness. Improved light sources and scanning methods in optical coherence tomography (OCT) have led to rapid growth in systems for high-resolution, quantitative elastography using imaged displacements and strains within soft tissue to infer local mechanical properties. We describe in some detail the physical processes underlying tissue mechanical response based on static and dynamic displacement methods. Namely, the assumptions commonly used to interpret displacement and strain measurements in terms of tissue elasticity for static OCE and propagating wave modes in dynamic OCE are discussed with the ultimate focus on OCT system design for ophthalmic applications. Practical OCT motion-tracking methods used to map tissue elasticity are also presented to fully describe technical developments in OCE, particularly noting those focused on the anterior segment of the eye. Clinical issues and future directions are discussed in the hope that OCE techniques will rapidly move forward to translational studies and clinical applications.
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Affiliation(s)
- Mitchell A. Kirby
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - Ivan Pelivanov
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - Shaozhen Song
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - Łukasz Ambrozinski
- Akademia Górniczo-Hutnicza University of Science and Technology, Krakow, Poland
| | - Soon Joon Yoon
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - Liang Gao
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - David Li
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
- University of Washington, Department of Chemical Engineering, Seattle, Washington, United States
| | - Tueng T. Shen
- University of Washington, Department of Ophthalmology, Seattle, Washington, United States
| | - Ruikang K. Wang
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
- University of Washington, Department of Ophthalmology, Seattle, Washington, United States
| | - Matthew O’Donnell
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
- Address all correspondence to: Matthew O’Donnell, E-mail:
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Tekin K, Erol YO, Inanc M, Sargon MF, Can CU, Polat S, Yilmazbas P. Electron microscopic evaluation of anterior lens epithelium in patients with idiopathic congenital cataract. Int Ophthalmol 2017; 38:2127-2132. [PMID: 28942547 DOI: 10.1007/s10792-017-0713-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 09/16/2017] [Indexed: 12/14/2022]
Abstract
PURPOSE To investigate the ultrastructure of the lens epithelial cells (LECs) in patients with idiopathic congenital cataract. METHODS This is a prospective interventional study. The anterior lens capsules (aLC: basement membrane and associated LECs) were taken from 16 eyes of 12 consecutive patients who were diagnosed as having idiopathic congenital cataracts. The aLCs were obtained from cataract surgery and prepared for transmission electron microscopy (TEM). RESULTS Some significant ultrastructural changes were observed in all aLCs of the participants. The anterior LECs showed alterations in different areas which were partly cuboidal and partly squamous in shape. The LECs had euchromatic nucleus and included some vacuoles in the cytoplasms as a remarkable alteration. The sizes of these intraepithelial cell vacuoles were changeable. CONCLUSIONS We identified remarkable changes in LECs of the eyes with idiopathic congenital cataract by TEM. It can be assumed that oxidative damage may be associated with these ultrastructural changes in LECs of the eyes with idiopathic congenital cataracts.
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Affiliation(s)
- Kemal Tekin
- Ankara Ulucanlar Eye Training and Research Hospital, 06240, Ankara, Turkey.
| | | | - Merve Inanc
- Ankara Ulucanlar Eye Training and Research Hospital, 06240, Ankara, Turkey
| | | | - Cigdem Ulku Can
- Ankara Ulucanlar Eye Training and Research Hospital, 06240, Ankara, Turkey
| | - Sibel Polat
- Ankara Ulucanlar Eye Training and Research Hospital, 06240, Ankara, Turkey
| | - Pelin Yilmazbas
- Ankara Ulucanlar Eye Training and Research Hospital, 06240, Ankara, Turkey
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Burd HJ, Montenegro GA, Panilla Cortés L, Barraquer RI, Michael R. Equatorial wrinkles in the human lens capsule. Exp Eye Res 2017; 159:77-86. [PMID: 28202286 DOI: 10.1016/j.exer.2017.02.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 11/29/2016] [Accepted: 02/09/2017] [Indexed: 11/26/2022]
Abstract
Equatorial wrinkles, or crenations, have been previously observed around the equator in coronal images of the human ocular lens. However, wrinkles are typically not apparent when the lens is viewed from saggital directions. In the current paper, the existence and geometry of these wrinkles is shown to be consistent with a mechanical model of the isolated lens, in which the capsule is held in a state of residual tension by a spatially uniform internal pressure. The occurrence of equatorial wrinkles is therefore seen to be a mechanical consequence of the spheroidal shape of the lens capsule and an excess intralenticular pressure. New observations are made, on post mortem lenses, on the geometric arrangement of these equatorial wrinkles. These observations indicate a well-defined pattern in which wrinkles exists along meridional lines in the equatorial regions of the lens. A preliminary 'puncture test' is used to demonstrate that the residual stresses within the capsule in the equatorial region of the lens are broadly consistent with the proposed mechanical model of the lens capsule. It is suggested that the presence of equatorial wrinkles may have an influence on the mechanical performance of the capsule during the accommodation process.
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Affiliation(s)
- H J Burd
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK.
| | - G A Montenegro
- Institut Universitari Barraquer, Universitat Autonoma de Barcelona, Barcelona, Spain
| | - L Panilla Cortés
- Institut Universitari Barraquer, Universitat Autonoma de Barcelona, Barcelona, Spain
| | - R I Barraquer
- Institut Universitari Barraquer, Universitat Autonoma de Barcelona, Barcelona, Spain; Centro de Oftalmología Barraquer, Universitat Internacional de Catalunya, Barcelona, Spain
| | - R Michael
- Institut Universitari Barraquer, Universitat Autonoma de Barcelona, Barcelona, Spain
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Stafiej J, Hałas-Wiśniewska M, Izdebska M, Gagat M, Grzanka D, Grzanka A, Malukiewicz G. Immunohistochemical analysis of microsomal glutathione S-transferase 1 and clusterin expression in lens epithelial cells of patients with pseudoexfoliation syndrome. Exp Ther Med 2017; 13:1057-1063. [PMID: 28450942 DOI: 10.3892/etm.2017.4085] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 11/24/2016] [Indexed: 12/15/2022] Open
Abstract
Pseudoexfoliation syndrome (PEX) is an age-associated, sight disorder affecting elastic fibers in the eye and visceral organs but its exact etiology remains unknown. The purpose of the current study was to determine the morphology and ultrastructure of lens epithelial cells (LECs), and to use immunohistochemistry to examine localization of microsomal glutathione S-transferase 1 (MGST1) and clusterin. Anterior lens capsules were obtained from 24 patients (13 PEX and 11 controls) who underwent phacoemulsification. Immunohistochemistry was performed, using antibodies against MGST1 and clusterin, to determine their expression. The morphology and ultrastructure of LECs were evaluated by light and transmission electron microscopy, respectively. The PEX LECs were characterized by significantly lower MGST1 (P=0.0001) and clusterin expression (P=0.0005) compared with the control group patients. PEX LECs were also observed to have significantly increased thickness compared with the control group patients (P=0.0002). The current findings suggest that low MGST1 and clusterin expression levels may be an early clinical indicator of PEX, and that oxidative stress may serve an important role, but that the specific etiology of this disease has yet to be revealed.
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Affiliation(s)
- Joanna Stafiej
- Department of Ophthalmology, Faculty of Medicine, Nicolaus Copernicus University Collegium Medicum in Bydgoszcz, 85-094 Bydgoszcz, Poland
| | - Marta Hałas-Wiśniewska
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University Collegium Medicum in Bydgoszcz, 85-092 Bydgoszcz, Poland
| | - Magdalena Izdebska
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University Collegium Medicum in Bydgoszcz, 85-092 Bydgoszcz, Poland
| | - Maciej Gagat
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University Collegium Medicum in Bydgoszcz, 85-092 Bydgoszcz, Poland
| | - Dariusz Grzanka
- Department of Dermatology, Sexually Transmitted Diseases and Immunodermatology, Faculty of Medicine, Nicolaus Copernicus University Collegium Medicum in Bydgoszcz, 85-094 Bydgoszcz, Poland
| | - Alina Grzanka
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University Collegium Medicum in Bydgoszcz, 85-092 Bydgoszcz, Poland
| | - Grażyna Malukiewicz
- Department of Ophthalmology, Faculty of Medicine, Nicolaus Copernicus University Collegium Medicum in Bydgoszcz, 85-094 Bydgoszcz, Poland
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Donaldson PJ, Grey AC, Maceo Heilman B, Lim JC, Vaghefi E. The physiological optics of the lens. Prog Retin Eye Res 2017; 56:e1-e24. [DOI: 10.1016/j.preteyeres.2016.09.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 09/09/2016] [Accepted: 09/13/2016] [Indexed: 11/17/2022]
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Schwarz C, Aldrich BT, Burckart KA, Schmidt GA, Zimmerman MB, Reed CR, Greiner MA, Sander EA. Descemet membrane adhesion strength is greater in diabetics with advanced disease compared to healthy donor corneas. Exp Eye Res 2016; 153:152-158. [PMID: 27777123 DOI: 10.1016/j.exer.2016.10.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 10/19/2016] [Accepted: 10/20/2016] [Indexed: 11/27/2022]
Abstract
Descemet membrane endothelial keratoplasty (DMEK) is an increasingly popular surgical procedure for treating ocular diseases that require a corneal transplant. Previous studies have found that tissue tearing during surgical preparation is more likely elevated in eyes from donors with a history of diabetes mellitus. To quantify these potential differences, we established an experimental technique for quantifying the force required to separate the endothelium-Descemet membrane complex (EDM) from stroma in human donor corneal tissue, and we assessed differences in adhesion strength between diabetic and non-diabetic donor corneas. Transplant suitable corneas were obtained from 23 donors 50-75 years old with an average preservation to assay time of 11.5 days. Corneas were classified from a medical records review as non-diabetic (ND, n = 9), diabetic without evidence of advanced disease (NAD, n = 8), or diabetic with evidence of advanced disease (AD, n = 10). Corneas were sectioned into 3 mm wide strips and the EDM peeled from the stroma. Using the force-extension data obtained from mechanical peel testing, EDM elastic peel tension (TE), elastic stiffness (SE), average delamination tension (TD), and maximum tension (TMAX) were calculated. Mean TE, SE, TD, and TMAX values for ND corneas were 0.78 ± 0.07 mN/mm, 0.37 ± 0.05 mN/mm/mm, 0.78 ± 0.08 mN/mm, and 0.94 ± 0.17 mN/mm, respectively. NAD values did not differ significantly. However, AD values for TE (1.01 ± 0.18 mN/mm), TD (1.09 ± 0.21 mN/mm), and TMAX (1.37 ± 0.24 mN/mm) were greater than ND and NAD corneas (P < 0.05). SE did not differ significantly between groups. These findings provide proof of the concept that chronic hyperglycemia from diabetes mellitus results in a phenotypically more adhesive interface between Descemet membrane and the posterior stroma in donor corneal tissue. Results of this study provide a foundation for further investigations into the impact of diabetes on the posterior cornea, eye banking, and keratoplasty.
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Affiliation(s)
- Chaid Schwarz
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
| | - Benjamin T Aldrich
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, IA, USA; Iowa Lions Eye Bank, Coralville, IA, USA
| | | | | | - M Bridget Zimmerman
- College of Public Health, Department of Biostatistics, University of Iowa, Iowa City, IA, USA
| | | | - Mark A Greiner
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, IA, USA; Iowa Lions Eye Bank, Coralville, IA, USA; Cornea Research Center, Stephen A. Wynn Institute for Vision Research, Iowa City, IA, USA.
| | - Edward A Sander
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA.
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David G, Pedrigi RM, Humphrey JD. Accommodation of the human lens capsule using a finite element model based on nonlinear regionally anisotropic biomembranes. Comput Methods Biomech Biomed Engin 2016; 20:302-307. [PMID: 27609339 DOI: 10.1080/10255842.2016.1228907] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Accommodation of the eyes, the mechanism that allows humans to focus their vision on near objects, naturally diminishes with age via presbyopia. People who have undergone cataract surgery, using current surgical methods and artificial lens implants, are also left without the ability to accommodate. The process of accommodation is generally well known; however the specific mechanical details have not been adequately explained due to difficulties and consequences of performing in vivo studies. Most studies have modeled the mechanics of accommodation under assumptions of a linearly elastic, isotropic, homogenous lens and lens capsule. Recent experimental and numerical studies showed that the lens capsule exhibits nonlinear elasticity and regional anisotropy. In this paper we present a numerical model of human accommodation using a membrane theory based finite element approach, incorporating recent findings on capsular properties. This study seeks to provide a novel perspective of the mechanics of accommodation. Such findings may prove significant in seeking biomedical solutions to restoring loss of visual power.
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Affiliation(s)
- G David
- a Institute of Mathematics , University of the Philippines , Quezon City , Philippines
| | - R M Pedrigi
- b Department of Bioengineering , Imperial College London , London , UK
| | - J D Humphrey
- c Department of Biomedical Engineering , Yale University , New Haven , CT , USA
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Ullrich F, Lussi J, Felekis D, Michels S, Petruska AJ, Nelson BJ. Perforation forces of the intact porcine anterior lens capsule. J Mech Behav Biomed Mater 2016; 62:347-354. [DOI: 10.1016/j.jmbbm.2016.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 04/28/2016] [Accepted: 05/04/2016] [Indexed: 11/24/2022]
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