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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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Huang J, Nie K, Lv X, Liu Y, Yang G, Fu J, Liu L, Lv H. Abnormal lens thickening in a child with Weill-Marchesani syndrome 4: A 3-year follow-up case report. Front Med (Lausanne) 2023; 9:1021489. [PMID: 36698805 PMCID: PMC9868407 DOI: 10.3389/fmed.2022.1021489] [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: 08/17/2022] [Accepted: 12/19/2022] [Indexed: 01/10/2023] Open
Abstract
Background Weill-Marchesani syndrome 4 (WMS4) is caused by ADAMTS17 gene variant and clinical abnormalities including lenticular myopia, ectopia lentis, glaucoma, microspherophakia, brachydactyly, and short stature. Due to free of heart defects and joint stiffness compared with other WMS forms, WMS4 has an insidious onset and is often misdiagnosed as high myopia. We combined multiple imaging biometry and whole-exome sequencing to diagnose a case of WMS4 with a 3-year follow-up. Case presentation An 8-year-old boy presented to our ophthalmology department with progressive myopia for 1 year. He had high myopia in both eyes with normal funds, intraocular pressure, and axial length. Ocular examination revealed thicker lenses (right 4.38 mm, left 4.31 mm) with a smaller equatorial diameter (right 7.33 mm and left 7.17 mm) compared to normal children of the same age. Finger length measurement indicates brachydactyly. Whole-exome sequencing identified compound heterozygous missense variants c.2984G > A (p.Arg995Gln) and c.2254A > G (p.Ile752Val) in the ADAMTS17 gene. During the 3 years of follow-up, the thickness of lenses increased significantly (right 4.49 mm, left 4.48 mm), but the equatorial diameter of the lenses had no significant change (right 7.32 mm, left 7.21 mm). As the equivalent lens power increased, the patient's myopia spherical refractive error rose accordingly. Although the anterior chamber angle remained open during follow-up, the intraocular pressure increased to right 20.4 mmHg and left 19.6 mmHg, Iridodonesis and short stature were present. Conclusion This case report highlights the abnormal thickening of the lens in WMS4 compared to the physiological thinning process during childhood. Comprehensive clinical examinations and genetic testing may improve diagnosis, which allows early therapeutic interventions for complications and better visual outcomes for the patient.
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Affiliation(s)
- Junting Huang
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Kailai Nie
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China,Research Laboratory of Ophthalmology and Vision Sciences, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Xinpin Lv
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Yuting Liu
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Guiqi Yang
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Junjiang Fu
- Key Laboratory of Epigenetics and Oncology, The Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, China
| | - Longqian Liu
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China,*Correspondence: Longqian Liu,
| | - Hongbin Lv
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, China,Hongbin Lv,
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Mohamed A, Nandyala S, Ho A, Manns F, Parel JMA, Augusteyn RC. Relationship of the cornea and globe dimensions to the changes in adult human crystalline lens diameter, thickness and power with age. Exp Eye Res 2021; 209:108653. [PMID: 34097905 DOI: 10.1016/j.exer.2021.108653] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 04/30/2021] [Accepted: 05/31/2021] [Indexed: 10/21/2022]
Abstract
It is well known that human crystalline lens shape, dimensions and optical properties change throughout life and influence whole eye refraction. However, it is not clear if lens properties are associated with other ocular parameters. The purpose of the present study was to investigate the relationship of corneal and external globe dimensions with adult lens diameter (LD), lens thickness (LT) and lens power (LP) in order to determine if external factors influence lens properties. Postmortem human eyes (n = 66, age = 20-78 years) were obtained from the Ramayamma International Eye Bank, Hyderabad, India. Globe antero-posterior length (GAPL) and mean (average of horizontal and vertical) diameters of cornea (MCD) and globe (MGD) were measured using digital calipers. Eyes were dissected to produce ocular structures that contain the lens maintained in its accommodating framework, including intact zonules, ciliary body and sections of sclera. Specimens were mounted in a mechanical lens stretching system. LD, LT and LP were measured using high magnification retro-illumination photography, slit illumination photography and Scheiner principle-based optical system respectively in the unstretched (accommodated) state. Relationships between external globe and corneal dimensions and LD, LT or LP were assessed by multiple regression analysis. Age (0.012 ± 0.003 mm/year; p<0.001) and GAPL (0.185 ± 0.045 mm/mm; p<0.001) were significant (p<0.0001) predictors of LD. After adjusting for age-related increases, LD appears to be positively correlated with GAPL. Age (0.010 ± 0.004 mm/year; p = 0.009) and GAPL (-0.143 ± 0.060 mm/mm; p = 0.02) were significant (p = 0.001) predictors of LT. After adjusting for the age-related increase, LT appears to be negatively correlated with GAPL. Only age was a significant predictor of LP (-0.26 ± 0.04 D/year; p<0.001). The results suggest that, apart from aging, lens diameter and thickness are dependent on the anteroposterior length of the eye globe. Lens power is not influenced by globe dimensions.
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Affiliation(s)
- Ashik Mohamed
- Ophthalmic Biophysics, L V Prasad Eye Institute, Hyderabad, India; Brien Holden Vision Institute Limited, Sydney, Australia; School of Optometry and Vision Science, The University of New South Wales, Sydney, NSW, Australia.
| | - Sushma Nandyala
- Ophthalmic Biophysics, L V Prasad Eye Institute, Hyderabad, India
| | - Arthur Ho
- Brien Holden Vision Institute Limited, Sydney, Australia; School of Optometry and Vision Science, The University of New South Wales, Sydney, NSW, Australia; Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Fabrice Manns
- Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, FL, USA
| | - Jean-Marie A Parel
- Brien Holden Vision Institute Limited, Sydney, Australia; Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, FL, USA; Anne Bates Leach Eye Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Robert C Augusteyn
- Brien Holden Vision Institute Limited, Sydney, Australia; School of Optometry and Vision Science, The University of New South Wales, Sydney, NSW, Australia; Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
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4
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Affiliation(s)
- Robert C Augusteyn
- Institute for Eye Research and the Vision Cooperative Research Centre, University of New South Wales, Sydney, Australia, and Biochemistry Department, LaTrobe University, Bundoora, Australia
E‐mail:
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Morphometric analysis of the lens in human aniridia and mouse Small eye. Exp Eye Res 2020; 203:108371. [PMID: 33248069 DOI: 10.1016/j.exer.2020.108371] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/17/2020] [Accepted: 11/22/2020] [Indexed: 12/16/2022]
Abstract
Congenital aniridia is caused by heterozygous mutations in the PAX6 gene. In this disease, congenital iris and foveal hypoplasia is associated with juvenile onset cataract, glaucoma, and corneal keratopathy. In rodents, Pax6 mutations result in a congenital reduction in ocular size that is not typically described in human aniridia. Here, the ocular morphometry of aniridia patients is compared with the lens phenotype of Pax6+/tm1/Pgr mice to reveal whether there are species differences in Pax6 regulation of lens development and homeostasis. Ultrasound biometry (UBM) revealed that eleven percent of aniridia patients exhibited mild microphthalmia while the anterior chamber depth of aniridic eyes was significantly reduced from 6 months of age onward. Although aniridic lens thickness was normal from birth, it was significantly decreased in aniridic lenses older than 30. Notably, 86% of aniridic lenses exhibited cataractous changes in this cohort. In addition, a significant proportion of aniridia patients develop lens subluxation as they age associated with reduced lens diameter as measured by anterior segment optical coherence tomography (AS-OCT). Analysis of young adult Pax6+/tm1/Pgr mouse lenses by micro-computed tomography (microCT), bright field and dark field imaging revealed that they are reduced in size but did not exhibit overt cataracts at this age. Overall, this study reveals that congenital microphthalmia as assessed by axial length, or microphakia, as assessed by lens thickness, are not typical in human aniridia, although these are primary manifestations of Pax6 mutations in mice, suggesting that PAX6 regulates some aspects of lens development differently between these species.
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Mohamed A, Durkee HA, Williams S, Manns F, Ho A, Parel JMA, Augusteyn RC. Morphometric analysis of in vitro human crystalline lenses using digital shadow photogrammetry. Exp Eye Res 2020; 202:108334. [PMID: 33121973 DOI: 10.1016/j.exer.2020.108334] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/17/2020] [Accepted: 10/22/2020] [Indexed: 10/23/2022]
Abstract
There is a great need for accurate biometric data on human lenses. To meet this, a compact tabletop optical comparator, the minishadowgraph, was built for measuring isolated eye lens shape and dimensions while the lens was fully immersed in supporting medium. The instrument was based around a specially designed cell and an illumination system which permitted image recording in both sagittal and equatorial (coronal) directions. Data were acquired with a digital camera and analyzed using a specially written MATLAB program as well as by manual measurements in image analysis software. The possible effect of lens orientation and gravity on the dimensions was examined by measuring dimensions with anterior or posterior surfaces up and by measuring lenses with calipers after removal from the minishadowgraph cell. Dimensions, curvatures and shape factors were obtained for 134 fully accommodated lenses ranging in age from birth to 88 years postnatal. Of these, 41 were from donors aged under 20 years, ages which are generally of limited availability. Thickness and diameter showed the same age-related trends described in previous studies but, for the lenses measured in air, age-dependent differences were observed in thickness (-5 to 0%) and diameter (+5 to 0%), consistent with gravitational sag. Anterior and posterior radii of curvature of the central 3 or 6 mm, depending on lens diameter, increase with age, with the anterior increase greater than the posterior. The anterior surface shape of the neonatal lens is that of a prolate ellipse and the posterior, an oblate ellipse. Both surfaces become hyperbolic after age 20. The data presented here on dimensions, shape and sagging will be of great value in assessing age-related changes in the optical and mechanical performance of the lens. In particular, the comprehensive data set from donors aged under 20 years provides a unique and valuable insight to the changes in size and shape during the early dynamic growth period of the lens.
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Affiliation(s)
- Ashik Mohamed
- Ophthalmic Biophysics, L V Prasad Eye Institute, Hyderabad, India; Brien Holden Vision Institute Limited, Sydney, Australia; School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
| | - Heather A Durkee
- Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, FL, USA
| | - Siobhan Williams
- Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, FL, USA
| | - Fabrice Manns
- Brien Holden Vision Institute Limited, Sydney, Australia; Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, FL, USA
| | - Arthur Ho
- Brien Holden Vision Institute Limited, Sydney, Australia; School of Optometry and Vision Science, University of New South Wales, Sydney, Australia; Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jean-Marie A Parel
- Brien Holden Vision Institute Limited, Sydney, Australia; Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, FL, USA
| | - Robert C Augusteyn
- Brien Holden Vision Institute Limited, Sydney, Australia; School of Optometry and Vision Science, University of New South Wales, Sydney, Australia; Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA.
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Jaimes-Nájera A, Gómez-Correa JE, Coello V, Pierscionek BK, Chávez-Cerda S. Single function crystalline lens capable of mimicking ciliary body accommodation. BIOMEDICAL OPTICS EXPRESS 2020; 11:3699-3716. [PMID: 33014561 PMCID: PMC7510927 DOI: 10.1364/boe.386459] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 05/08/2020] [Accepted: 05/08/2020] [Indexed: 06/11/2023]
Abstract
The lens is a complex optical component of the human eye because of its physiological structure: the surface is aspherical and the structural entities create a gradient refractive index (GRIN). Most existent models of the lens deal with its external shape independently of the refractive index and, subsequently, through optimization processes, adjust the imaging properties. In this paper, we propose a physiologically realistic GRIN model of the lens based on a single function for the whole lens that accurately describes different accommodative states simultaneously providing the corresponding refractive index distribution and the external shape of the lens by changing a single parameter that we associate with the function of the ciliary body. This simple, but highly accurate model, is incorporated into a schematic eye constructed with reported experimental biometric data and accommodation is simulated over a range of 0 to 6 diopters to select the optimum levels of image quality. Changes with accommodation in equatorial and total axial lens thicknesses, as well as aberrations, are found to lie within reported biometric data ranges.
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Affiliation(s)
- A Jaimes-Nájera
- Tecnológico de Monterrey, Escuela de Ingeniería y Ciencias, Monterrey, 64849, Mexico
- Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California, Unidad Monterrey, PIIT Apodaca, NL 66629, Mexico
- Instituto Nacional de Astrofísica, Óptica y Electrónica, Coordinación de Óptica, Tonantzintla Puebla, 72840, Mexico
| | - J E Gómez-Correa
- Cátedras Conacyt - Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California, Unidad Monterrey, PIIT Apodaca, NL 66629, Mexico
| | - V Coello
- Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California, Unidad Monterrey, PIIT Apodaca, NL 66629, Mexico
| | - B K Pierscionek
- School of Life Sciences and Education, Staffordshire University, College Road, Stoke-on-Trent, ST4 2DE, UK
| | - S Chávez-Cerda
- Instituto Nacional de Astrofísica, Óptica y Electrónica, Coordinación de Óptica, Tonantzintla Puebla, 72840, Mexico
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8
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Panoramic Observation of Crystalline Lenses with 25 MHz Ultrasonography. J Ophthalmol 2019; 2019:8319027. [PMID: 31827913 PMCID: PMC6885293 DOI: 10.1155/2019/8319027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 09/24/2019] [Accepted: 10/19/2019] [Indexed: 11/25/2022] Open
Abstract
Purpose To visualize and assess in vivo the age-related changes in crystalline lens size and contour. Methods Seventy-nine healthy volunteers, 39 females and 40 males, with a mean age of 41.53 + 11.32 years (range: 21 to 60 years) were enrolled in this study. The axial lens thickness (ALT), equatorial lens diameter (ELD), and anterior (Ra) and posterior (Rp) lens surface radii of curvatures of the subjects' left eyes were measured with a 25 MHz ultrasound probe. Results The mean ALT and ELD were 4.178 mm + 0.288 mm and 9.209 mm + 0.214 mm, respectively. There was a statistically significant increase in both ALT (slope = 11 μm/year, r = 0.88, p < 0.01) and ELD (slope = 6 μm/year, r = 0.60, p < 0.01) with age. Ra negatively correlated, and Rp did not change with age. Conclusion There were no statistically significant relationships between any studied values and gender. Independent of gender, the lens grows equatorially and axially with age while its central anterior lens surface steepens and its posterior central surface curvature does not change.
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Wenz D, Kuehne A, Huelnhagen T, Nagel AM, Waiczies H, Weinberger O, Oezerdem C, Stachs O, Langner S, Seeliger E, Flemming B, Hodge R, Niendorf T. Millimeter spatial resolution in vivo sodium MRI of the human eye at 7 T using a dedicated radiofrequency transceiver array. Magn Reson Med 2018; 80:672-684. [DOI: 10.1002/mrm.27053] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 10/18/2017] [Accepted: 11/30/2017] [Indexed: 12/23/2022]
Affiliation(s)
- Daniel Wenz
- Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association; Berlin Germany
| | | | - Till Huelnhagen
- Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association; Berlin Germany
| | - Armin M. Nagel
- Institute of Radiology; University Hospital Erlangen; Erlangen Germany
- Division of Medical Physics in Radiology, German Cancer Research Centre (DKFZ); Heidelberg Germany
| | | | - Oliver Weinberger
- Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association; Berlin Germany
| | - Celal Oezerdem
- Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association; Berlin Germany
| | - Oliver Stachs
- Department of Ophthalmology; University of Rostock; Rostock Germany
| | - Soenke Langner
- Institute for Diagnostic Radiology and Neuroradiology; University Medicine Greifswald; Greifswald Germany
| | - Erdmann Seeliger
- Institute of Physiology; Charité University Medicine; Berlin Germany
| | - Bert Flemming
- Institute of Physiology; Charité University Medicine; Berlin Germany
| | - Russell Hodge
- Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association; Berlin Germany
| | - Thoralf Niendorf
- Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association; Berlin Germany
- MRI.TOOLS GmbH; Berlin Germany
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Bassnett S, Šikić H. The lens growth process. Prog Retin Eye Res 2017; 60:181-200. [PMID: 28411123 DOI: 10.1016/j.preteyeres.2017.04.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 04/06/2017] [Accepted: 04/10/2017] [Indexed: 01/17/2023]
Abstract
The factors that regulate the size of organs to ensure that they fit within an organism are not well understood. A simple organ, the ocular lens serves as a useful model with which to tackle this problem. In many systems, considerable variance in the organ growth process is tolerable. This is almost certainly not the case in the lens, which in addition to fitting comfortably within the eyeball, must also be of the correct size and shape to focus light sharply onto the retina. Furthermore, the lens does not perform its optical function in isolation. Its growth, which continues throughout life, must therefore be coordinated with that of other tissues in the optical train. Here, we review the lens growth process in detail, from pioneering clinical investigations in the late nineteenth century to insights gleaned more recently in the course of cell and molecular studies. During embryonic development, the lens forms from an invagination of surface ectoderm. Consequently, the progenitor cell population is located at its surface and differentiated cells are confined to the interior. The interactions that regulate cell fate thus occur within the obligate ellipsoidal geometry of the lens. In this context, mathematical models are particularly appropriate tools with which to examine the growth process. In addition to identifying key growth determinants, such models constitute a framework for integrating cell biological and optical data, helping clarify the relationship between gene expression in the lens and image quality at the retinal plane.
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Affiliation(s)
- Steven Bassnett
- Department of Ophthalmology & Visual Sciences, Washington University School of Medicine, USA.
| | - Hrvoje Šikić
- Department of Mathematics, Faculty of Science, University of Zagreb, Croatia
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11
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Augusteyn RC. On the contribution of the nucleus and cortex to human lens shape and size. Clin Exp Optom 2017; 101:64-68. [PMID: 28370270 DOI: 10.1111/cxo.12539] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 01/19/2017] [Accepted: 01/24/2017] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND The shape of the human lens changes from almost spherical at birth to ellipsoid due to a decrease in sagittal thickness and an increase in equatorial diameter during the first two decades of life. Both dimensions increase thereafter. This study was undertaken to determine the reason for the change. METHODS Published refractive index gradients, from 20 lenses aged from seven to 82 years, were used to calculate the protein contents of concentric shells of fibre cells in human lenses. The boundaries of nuclear cores containing from 2.5 to 45 mg, in 2.5 mg increments, were determined from the isoindicial shells. Cortex thickness was determined from the distance between the 30 mg nuclear boundary and the capsule. RESULTS The sagittal thickness of every nuclear core decreased until age 40 years and remained constant thereafter. Over the same time frame, the equatorial diameter of the cores containing up to 30 mg of protein increased, while those of cores larger than 30 mg decreased. The volumes of the cores decreased and their shapes changed from near spherical to spheroidal. Equatorial and sagittal cortex thickness increased linearly with age at 0.0082 mm per year. The anterior sagittal cortex was 0.23 mm larger than the posterior and the equatorial cortex was 0.62 mm greater. CONCLUSIONS Changes in lens shape observed during the first two decades of life are due to remodelling and compaction of the 30 mg nuclear core. Cortex growth is linear throughout life.
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Affiliation(s)
- Robert C Augusteyn
- Vision Cooperative Research Centre, Brien Holden Vision Institute, Kensington, New South Wales, Australia.,School of Optometry and Vision Science, The University of New South Wales, Kensington, New South Wales, Australia.,Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
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12
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Giovanzana S, Schachar RA, Talu S, Kirby RD, Yan E, Pierscionek BK. Evaluation of equations for describing the human crystalline lens. JOURNAL OF MODERN OPTICS 2013. [DOI: 10.1080/09500340.2013.782432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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13
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Abstract
The successful development of biomaterials is increasingly influenced by biomimesis essentially the use of biological structures as design templates. This approach has been used here in the design of injectable systems for the nucleus of the intervertebral disc, corneal inlays and intraocular lenses (IOLs). The strategy is based on the use of C-linked sulphonates to mimic the O-linked sulphate groups that are the hydration drivers in proteoglycans. The elastic modulus of the materials can be tailored for specific applications.
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14
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Pierscionek BK, Li Y, Schachar RA, Chen W. The effect of high concentration and exposure duration of nanoceria on human lens epithelial cells. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2012; 8:383-90. [DOI: 10.1016/j.nano.2011.06.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 06/04/2011] [Accepted: 06/19/2011] [Indexed: 11/27/2022]
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15
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Giovanzana S, Talu S. Mathematical models for the shape analysis of human crystalline lens. JOURNAL OF MODERN OPTICS 2012. [DOI: 10.1080/09500340.2011.621035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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16
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Gutierrez DB, Garland D, Schey KL. Spatial analysis of human lens aquaporin-0 post-translational modifications by MALDI mass spectrometry tissue profiling. Exp Eye Res 2011; 93:912-20. [PMID: 22036630 DOI: 10.1016/j.exer.2011.10.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 10/17/2011] [Accepted: 10/17/2011] [Indexed: 10/16/2022]
Abstract
Aquaporin-0 (AQP0), the major integral membrane protein in lens fiber cells, becomes highly modified with increasing age. The functional consequences of these modifications are being revealed, and the next step is to determine how these modifications affect the ocular lens, which is directly related to their abundances and spatial distributions. The aim of this study was to utilize matrix-assisted laser desorption ionization (MALDI) direct tissue profiling methods, which produce spatially-resolved protein profiles, to map and quantify AQP0 post-translational modifications (PTMs). Direct tissue profiling was performed using frozen, equatorial human lens sections of various ages prepared by conditions optimized for MALDI mass spectrometry profiling of membrane proteins. Modified forms of AQP0 were identified and further investigated using liquid chromatography tandem mass spectrometry (LC-MS/MS). The distributions of unmodified, truncated, and oleoylated forms of AQP0 were examined with a maximum spatial resolution of 500 μm. Direct tissue profiling of intact human lens sections provided high quality, spatially-resolved, relative quantitative information of AQP0 and its modified forms indicating that 50% of AQP0 is truncated at a fiber cell age of 24 ± 1 year in all lenses examined. Furthermore, direct tissue profiling also revealed previously unidentified AQP0 modifications including N-terminal acetylation and carbamylation. N-terminal acetylation appears to provide a protective effect against N-terminal truncation.
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Affiliation(s)
- Danielle B Gutierrez
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, MD, USA
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Reilly MA, Andley UP. Quantitative biometric phenotype analysis in mouse lenses. Mol Vis 2010; 16:1041-6. [PMID: 20606707 PMCID: PMC2893053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Accepted: 06/01/2010] [Indexed: 12/03/2022] Open
Abstract
The disrupted morphology of lenses in mouse models for cataracts precludes accurate in vitro assessment of lens growth by weight. To overcome this limitation, we developed morphometric methods to assess defects in eye lens growth and shape in mice expressing the alphaA-crystallin R49C (alphaA-R49C) mutation. Our morphometric methods determine quantitative shape and dry weight of the whole lens from histological sections of the lens. This method was then used to quantitatively compare the biometric growth patterns of lenses of different genotypes of mice from birth to 12 months. The wild type dry lens weights determined using the morphometric method were comparable to previously reported weights. Next we applied the method to assessing the lenses of alphaA-R49C knock-in mice, which exhibit decreased alphaA-crystallin protein solubility, resulting in a variety of growth abnormalities including early cataract formation, decreased eye and lens size, failure to form the equatorial bow region, and continued lens cell death, sometimes resulting in the entire loss of the lens and eye. Our morphometric methods reproducibly quantified these defects by combining histology, microscopy, and image analysis. The volume measurement accurately represented the total growth of the lens, whereas the geometric shape of the lens more accurately quantified the differences between the growth of the mutant and wild-type lenses. These methods are robust tools for measuring dry lens weight and quantitatively comparing the growth of small lenses that are difficult to weigh accurately such as those from very young mice and mice with developmental lens defects.
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Affiliation(s)
- Matthew A. Reilly
- Department of Veterans Affairs Medical Center, St. Louis, MO,Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis, MO,Ophthalmology and Visual Sciences, Washington University in St. Louis, St. Louis, MO
| | - Usha P. Andley
- Ophthalmology and Visual Sciences, Washington University in St. Louis, St. Louis, MO
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18
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Abstract
In order to propose a method of intraocular imaging system for the visual prosthesis, an implantable microcamera was developed and evaluated in vivo. The microcamera was specially developed and shaped to fit the rabbit's lens capsule and encapsulated with the biocompatible silicone. To evaluate the feasibility of this novel approach, the custom-built device was implanted following the surgical extraction of rabbit's lens. And clinical examinations were performed 1 day, 3 days, 1 week, 2 week, and 1 month postoperatively, including slit-lamp examination, intraocular pressure, wound status, anterior chamber depth, the presence of the iris fibrosi of neovascularization, and the position of the implant. Real-time imaging was performed in vivo 1 month after the operation, and the acquired images were processed with the software and hardware that were specially developed for generating the stimulating pulses. Short-term results showed the novel approach is promising.
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Affiliation(s)
- Chuanqing Zhou
- Department of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
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19
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Augusteyn RC. On the growth and internal structure of the human lens. Exp Eye Res 2010; 90:643-54. [PMID: 20171212 DOI: 10.1016/j.exer.2010.01.013] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 01/25/2010] [Accepted: 01/29/2010] [Indexed: 11/27/2022]
Abstract
Growth of the human lens and the development of its internal features are examined using in vivo and in vitro observations on dimensions, weights, cell sizes, protein gradients and other properties. In vitro studies have shown that human lens growth is biphasic, asymptotic until just after birth and linear for most of postnatal life. This generates two distinct compartments, the prenatal and the postnatal. The prenatal growth mode leads to the formation of an adult nuclear core of fixed dimensions and the postnatal, to an ever-expanding cortex. The nuclear core and the cortex have different properties and can readily be physically separated. Communication and adhesion between the compartments is poor in older lenses. In vivo slit lamp examination reveals several zones of optical discontinuity in the lens. Different nomenclatures have been used to describe these, with the most common recognizing the embryonic, foetal, juvenile and adult nuclei as well as the cortex and outer cortex. Implicit in this nomenclature is the idea that the nuclear zones were generated at defined periods of development and growth. This review examines the relationship between the two compartments observed in vitro and the internal structures revealed by slit lamp photography. Defining the relationship is not as simple as it might seem because of remodeling and cell compaction which take place, mostly in the first 20 years of postnatal life. In addition, different investigators use different nomenclatures when describing the same regions of the lens. From a consideration of the dimensions, the dry mass contents and the protein distributions in the lens and in the various zones, it can be concluded that the juvenile nucleus and the layers contained within it, as well as most of the adult nucleus, were actually produced during prenatal life and the adult nucleus was completed within 3 months after birth, in the final stages of the prenatal growth mode. Further postnatal growth takes place entirely within the cortex. It can also be demonstrated that the in vitro nuclear core corresponds to the combined slit lamp nuclear zones. In view of the information presented in this review, the use of the terms foetal, juvenile and adult nucleus seems inappropriate and should be abandoned.
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Affiliation(s)
- Robert C Augusteyn
- The Vision Cooperative Research Centre, School of Optometry, University of NSW, Sydney, NSW 2052, Australia.
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20
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Tkatchenko TV, Shen Y, Tkatchenko AV. Analysis of postnatal eye development in the mouse with high-resolution small animal magnetic resonance imaging. Invest Ophthalmol Vis Sci 2009; 51:21-7. [PMID: 19661239 DOI: 10.1167/iovs.08-2767] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Studies of myopia in mice have been complicated by the difficulty in obtaining accurate measurements of small changes observed in the growing mouse eye in vivo and the lack of data on refractive eye development. The purpose of this study was to carry out an in vivo high-resolution analysis of mouse eye growth and refractive development. METHODS High-resolution small animal magnetic resonance imaging and high-resolution infrared photorefraction were used to analyze refractive development in postnatal day (P)21 to P89 C57BL/6J mice. RESULTS The growth of the mouse eye decelerated after P40. The eye maintained a slightly prolate shape during growth. The anterior chamber growth exhibited a similar pattern, whereas the corneal radius of curvature (CRC) increased linearly. The growth rate of the lens remained constant until P89. The lens "overgrew" the eye at P40, resulting in a decline in vitreous chamber depth. Mice showed myopic refractive errors at a younger age (-13.2 +/- 2.0 D; mean +/- SD, P21). The refractive errors stabilized around emmetropic values by P32 and remained emmetropic until P40. Mice became progressively hyperopic with age (+1.2 +/- 1.7 D, P67; +3.6 +/- 2.3 D, P89). CONCLUSIONS Development of ocular components in the mouse is similar to that of the tree shrew but different from that of higher primates and humans. Primary differences can be attributed to the age-related changes of the crystalline lens and CRC. In spite of these differences, mice appear to be able to achieve and maintain emmetropic refractive status at P32 to P40.
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Affiliation(s)
- Tatiana V Tkatchenko
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan 48201, USA
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21
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Augusteyn RC, Vrensen G, Willekens B. The effect of paraformaldehyde fixation and PBS storage on the water content of the human lens. Mol Vis 2008; 14:90-4. [PMID: 18253098 PMCID: PMC2254961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 12/29/2007] [Indexed: 11/27/2022] Open
Abstract
PURPOSE Fixation and phosphate buffered saline (PBS) storage are frequently used before studies of the morphological, biochemical, and optical properties of the human lens begin. It is assumed that this does not alter the properties being examined. The present study was undertaken to determine the effects of fixation and PBS storage on the human lens wet weight. METHODS Human donor lenses were incubated in a buffered paraformaldehyde (PF) solution or in PBS and their wet weights were monitored for up to 44 and 13 days, respectively. RESULTS PF fixation resulted in a large decrease in wet weight, averaging 25%+/-2.3% at 30 days for 14 human donor lenses, aged 49-80 years. The loss was essentially complete by 21 days. Out of the 10 lenses, aged 52-71 years, which were incubated in PBS alone, six of them increased in weight by an average of 38% over 13 days and four ruptured within four days. Comparison of literature data for a fixed eight-year-old lens with those for an unfixed seven-year-old lens indicated that the decrease in wet weight was due mainly to a loss of water from the cortex, which resulted in virtual disappearance of the water/protein gradient and the formation of a plateau containing 58% water in over 90% of the lens. CONCLUSIONS Fixation substantially alters the amount and distribution of water in the human lens. Caution should be exercised when interpreting data on water and protein distributions as well as cell dimensions obtained with lenses which have been fixed. In addition, prolonged storage of a lens in PBS will result in substantial water uptake, which may affect measurements of their dimensions and optical properties.
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Affiliation(s)
- Robert C Augusteyn
- Vision Cooperative Research Centre, Sydney, Australia and Department of Biochemistry and Molecular Biology, La Trobe University, Bundoora Australia.
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22
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Equatorial Lens Growth Predicts the Age-related Decline in Accommodative Amplitude That Results in Presbyopia and the Increase in Intraocular Pressure That Occurs With Age. Clin Ophthalmol 2008; 48:1-8. [DOI: 10.1097/iio.0b013e31815eb836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Schachar RA, Fygenson DK. Topographical changes of biconvex objects during equatorial traction: an analogy for accommodation of the human lens. Br J Ophthalmol 2007; 91:1698-703. [PMID: 16837546 PMCID: PMC2095551 DOI: 10.1136/bjo.2006.094888] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2006] [Indexed: 11/03/2022]
Abstract
AIM To assess and compare the changes in shape of encapsulated biconvex structures undergoing equatorial traction with those changes reported in the human lens during accommodation. METHODS Equatorial traction was applied to several different biconvex structures: air, water, and gel filled mylar and rubber balloons and spherical vesicles. In the vesicles, traction was applied externally, using optical tweezers, or from within, by the assembly of encapsulated microtubules. The shape changes were recorded photographically and the change in central radius of curvature of water filled mylar balloons was quantified. RESULTS Whenever an outward equatorial force was applied to the long axis of long oval biconvex objects, where the minor to major axis ratio was =0.6, the central surfaces steepened and the peripheral surfaces flattened. Similar changes in the shape of the lens have been reported during human in vivo accommodation. CONCLUSIONS All biconvex structures that have been studied demonstrate similar shape changes in response to equatorial traction. This effect is independent of capsular thickness. The consistent observation of this physical change in the configuration of biconvex structures in response to outward equatorial force suggests that this may be a universal response of biconvex structures, also applicable to the human lens undergoing accommodation.
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Affiliation(s)
- R A Schachar
- Department of Physics, University of Texas at Arlington, Arlington, Texas, USA.
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24
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Schachar RA. Comment on the publication "Stiffness gradient in the crystalline lens" by H.A. Weeber et al. Graefes Arch Clin Exp Ophthalmol 2007; 245:1405-6; author reply 1047-8. [PMID: 17622549 DOI: 10.1007/s00417-007-0628-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Accepted: 06/11/2007] [Indexed: 10/23/2022] Open
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25
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Abolmaali A, Schachar RA, Le T. Sensitivity study of human crystalline lens accommodation. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2007; 85:77-90. [PMID: 17005291 DOI: 10.1016/j.cmpb.2006.08.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Revised: 08/22/2006] [Accepted: 08/24/2006] [Indexed: 05/12/2023]
Abstract
A nonlinear axisymmetric finite element method (FEM) analysis was employed to determine the critical geometric and material properties that affect human accommodation. In this model, commencing at zero, zonular traction on all lens profiles resulted in central lenticular surface steepening and peripheral surface flattening, with a simultaneous increase in central lens thickness and central optical power. An age-related decline in maximum zonular tension appears to be the most likely etiology for the decrease in accommodative amplitude with age.
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Affiliation(s)
- A Abolmaali
- Department of Civil and Environmental Engineering, University of Texas at Arlington, TX 76019, USA
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26
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Schachar RA. Effect of change in central lens thickness and lens shape on age-related decline in accommodation. J Cataract Refract Surg 2006; 32:1897-8; author reply 1898. [PMID: 17081877 DOI: 10.1016/j.jcrs.2006.05.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Accepted: 05/30/2006] [Indexed: 11/20/2022]
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27
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Affiliation(s)
- Ronald A Schachar
- Department of Physics, University of Texas at Arlington, PO Box 601149, Dallas, TX 75360, USA
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28
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Hu CY. Effect of change in central lens thickness and lens shape on age-related decline in accommodation. J Cataract Refract Surg 2006. [DOI: 10.1016/j.jcrs.2006.06.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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29
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Schachar RA, Abolmaali A, Le T. Insights into the age-related decline in the amplitude of accommodation of the human lens using a non-linear finite-element model. Br J Ophthalmol 2006; 90:1304-9. [PMID: 16854823 PMCID: PMC1857424 DOI: 10.1136/bjo.2006.100347] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2006] [Indexed: 11/04/2022]
Abstract
AIM To understand the effect of the geometric and material properties of the lens on the age-related decline in accommodative amplitude. METHODS Using a non-linear finite-element model, a parametric assessment was carried out to determine the effect of stiffness of the cortex, nucleus, capsule and zonules, and that of thickness of the capsule and lens, on the change in central optical power (COP) associated with zonular traction. Convergence was required for all solutions. RESULTS Increasing either capsular stiffness or capsular thickness was associated with an increase in the change in COP for any specific amount of zonular traction. Weakening the attachment between the capsule and its underlying cortex increased the magnitude of the change in COP. When the hardness of the total lens stroma, cortex or nucleus was increased, there was a reduction in the amount of change in COP associated with a fixed amount of zonular traction. CONCLUSIONS Increasing lens hardness reduces accommodative amplitude; however, as hardness of the lens does not occur until after the fourth decade of life, the age-related decline in accommodative amplitude must be due to another mechanism. One explanation is a progressive decline in the magnitude of the maximum force exerted by the zonules with ageing.
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MESH Headings
- Accommodation, Ocular/physiology
- Adult
- Aging/pathology
- Aging/physiology
- Elasticity
- Finite Element Analysis
- Humans
- Lens Capsule, Crystalline/anatomy & histology
- Lens Capsule, Crystalline/physiology
- Lens Cortex, Crystalline/anatomy & histology
- Lens Cortex, Crystalline/physiology
- Lens Nucleus, Crystalline/anatomy & histology
- Lens Nucleus, Crystalline/physiology
- Lens, Crystalline/anatomy & histology
- Lens, Crystalline/physiology
- Middle Aged
- Models, Biological
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Affiliation(s)
- R A Schachar
- Department of Physics, University of Texas at Arlington, Arlington, TX, USA.
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