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Zhang G, Jiang J, Wei Q, Qu C. Effects of accommodation on geometrical parameters of human lens: A systematic review and meta-analysis. Heliyon 2024; 10:e29298. [PMID: 38681553 PMCID: PMC11053204 DOI: 10.1016/j.heliyon.2024.e29298] [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: 07/02/2023] [Revised: 03/29/2024] [Accepted: 04/04/2024] [Indexed: 05/01/2024] Open
Abstract
Purpose To investigate the effects of accommodation on the geometrical parameters of human lens. Methods Eight databases from inception to November 2023 were used for the literature search: CNKI, CBM, VIP, Wan-Fang, PubMed, Web of Science, EMBASE, and the Cochrane Library. The Methodological Index for Non-randomized Studies was used to assess the risk of bias. The PRISMA were followed and the following outcomes were taken into consideration: lens diameter (LD), lens thickness (LT), anterior curvature radius (ACR), posterior curvature radius (PCR), lens center position (LCP), and total cross-sectional area (TCSA). This systematic review was registered on an international platform for registered systematic reviews and meta-analysis (INPLASY202260085). Results A total of 19 studies were included. LT increased by 0.04 mm/D (18 studies; 95% confidence interval [CI], 0.03-0.06; I2 = 96.6%; P < 0.001). At the same time, LD, ACR, and PCR decreased by 0.06 mm/D (6 studies; 95%CI, -0.07-0.05; I2 = 50.1%; P < 0.001), 0.53 mm/D (8 studies; 95%CI, -0.64-0.41; I2 = 96.5%; P < 0.001), and 0.14 mm/D (9 studies; 95%CI, -0.19-0.09; I2 = 94.7%; P < 0.001) during accommodation, respectively. Moreover, LCP shifted forward by 0.01 mm/D (3 studies; 95%CI, -0.02-0.00; I2 = 0.0%; P < 0.001), and TCSA by 0.58 mm2/D (2 studies; 95%CI, 0.41-1.57; I2 = 97.0%; P = 0.457) during accommodation. Conclusions Changes in LT, LD, ACR, PCR and LCP supported Helmholtz's theory. Different apparatuses or measurement methods influenced the measurement of lens geometrical parameters.
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Affiliation(s)
- Guanghong Zhang
- Department of Ophthalmology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN 611731, China
- School of Medicine, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN 611731, China
- Sichuan Key Laboratory for Disease Gene Study, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, No. 32 of the West 2nd Section of First Ring Road, Chengdu 610072, China
| | - Jun Jiang
- Department of Ophthalmology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN 611731, China
- School of Medicine, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN 611731, China
- Sichuan Key Laboratory for Disease Gene Study, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, No. 32 of the West 2nd Section of First Ring Road, Chengdu 610072, China
| | - Qian Wei
- Southwest Medical University, No. 319, Section 3, Zhongshan Road, Luzhou 646000, China
| | - Chao Qu
- Department of Ophthalmology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN 611731, China
- School of Medicine, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN 611731, China
- Sichuan Key Laboratory for Disease Gene Study, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, No. 32 of the West 2nd Section of First Ring Road, Chengdu 610072, China
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Shen L, Wei C, Yang W, Xiong Y, Li Y, Li D, Wang Z, Chen W, Zhao Q, Li Y, Cui R, Liu Q. Analysis of the relationship between lens morphology and aberrations in patients with myopia: a cross-sectional study. Int Ophthalmol 2023; 43:4911-4919. [PMID: 37828345 DOI: 10.1007/s10792-023-02894-w] [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: 02/24/2023] [Accepted: 09/27/2023] [Indexed: 10/14/2023]
Abstract
PURPOSE To investigate the relationship between lens morphology and aberrations in patients with myopia. METHODS This cross-sectional study included 155 patients with myopia in their right eyes. Spherical power and cylindrical power were achieved by cycloplegic autorefraction. The eyes were divided into three groups for analysis based on their spherical equivalent (SE) values. The 4 mm and 6 mm ocular and internal aberrations were measured using the OPD-scan III. Lens parameters were measured using CASIA2, including lens thickness (LT), radius of anterior/posterior lens surface curvature (RAL/RPL), lens decentration (DEC), and lens tilt (TILT). The differences of lenticular parameters and aberration parameters among the three groups analyzed with ANOVA or Kruskal Wallis test. Pearson correlation or Spearman correlation analysis was performed to evaluate the relationships between the lens parameters and aberrations. A p value < 0.05 indicated statistical significance. RESULTS The difference in LT, RAL, DEC and TITL among the three groups was statistically significant (p < 0.05). And there were differences among differences in internal high-order aberrations, spherical aberration, and coma aberration(p < 0.05).Spherical power was positively correlated with LT and TITL (p < 0.05) and negatively correlated with DEC, RAL, and RPL (p < 0.05). Cylindrical power was positively correlated with LT (p < 0.05) and negatively correlated DEC (p < 0.05); The lenticular parameters (LT, RAL, DEC, and TILT) were mainly correlated with the ocular and internal spherical aberration. LT and DEC were correlated with ocular and internal higher-order aberrations and coma aberration. CONCLUSION DEC and LT were the main factors affecting aberrations in patients with myopia.
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Affiliation(s)
- Lin Shen
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Chuanchuan Wei
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Wenli Yang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China.
| | - Ying Xiong
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Yifan Li
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Dongjun Li
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Ziyang Wang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Wei Chen
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Qi Zhao
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Yifeng Li
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Rui Cui
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Qian Liu
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
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Analysis of the Changes and Possible Reasons in Aberrations before and after Surgery in Patients with Concomitant Exotropia. COMPUTATIONAL INTELLIGENCE AND NEUROSCIENCE 2022; 2022:5207553. [PMID: 36105630 PMCID: PMC9467761 DOI: 10.1155/2022/5207553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 07/21/2022] [Accepted: 08/16/2022] [Indexed: 11/17/2022]
Abstract
Objective. The objective is to observe the changes in aberrations before and after surgery in patients with common horizontal strabismus and to analyze the possible reasons for the changes. Methods. Forty eyes of 40 cases with concomitant exotropia who underwent strabismus correction at the Ophthalmology Department of Nantong University Hospital from October 2020 to July 2021 were included in this study, all of whom underwent unilateral lateral rectus recession combined with a medial rectus resection in the same eye. Aberration parameters were measured 1 day before surgery and 1 week, 1 month, 3 months, and 6 months after surgery. Differences in the indicators at each time period were compared by analysis of variance (ANOVA) of repeated measures data for a single factor, and data were analyzed using SPSS 25.0 statistical application software. Results. 5 mm pupil diameter: the preoperative and postoperative RMS of total aberration showed statistically significant difference (
). Postoperation test (Bonferroni method) and preoperative comparison at each period after surgery showed statistically significant differences between 6 months after surgery (
) and preoperative comparison. The preoperative and postoperative comparison of RMS in LOAs was statistically significant (
); postoperative test (Bonferroni method) and preoperative comparison showed that there were statistically significant differences between 1 week (
) and 6 months (
) after operation. The difference of RMS of defocus before and after operation was statistically significant (
); postoperation test (Bonferroni method) and preoperative comparison showed that there was statistically significant difference between 6 months after operation (
) and preoperative comparison. There was statistically significant difference in preoperative and postoperative RMS of HOAs (
). Postoperative test (Bonferroni method) and preoperative comparison showed that there was statistically significant difference 6 months after surgery (
). The RMS of secondary astigmatism showed a statistically significant difference before and after operation (
), and the postoperation test (Bonferroni method) showed a statistically significant difference 6 months after operation (
). In 5 mm pupil diameter, the preoperative and postoperative RMS of total aberration showed statistically significant difference (
), postoperative test (Bonferroni method) was used to compare each period after surgery with that before surgery, and there were statistically significant differences between 1 week after surgery (
), 3 months after surgery (
), and 6 months after surgery (
). The preoperative and postoperative comparison of RMS in LOAs was statistically significant (
), postoperative test (Bonferroni method) was used to compare each period after surgery with that before surgery, and there were statistically significant differences between 1 week after surgery (
), 3 months after surgery (
), and 6 months after surgery (
). The difference of RMS of defocus before and after surgery was statistically significant (
), and the comparison between postoperation test (Bonferroni method) and preoperation showed that the difference was statistically significant 6 months after surgery (
). The RMS of astigmatism showed statistically significant difference before and after operation (
), and the postoperation test (Bonferroni method) showed statistically significant difference between 6 months after operation (
) and before operation. Conclusion. We found that horizontal rectus surgery had a transient effect on LOAs and almost no effect on HOAs. Long-term follow-up is recommended after strabismus surgery to observe eye position and binocular visual function. Because of the high prevalence of strabismus in adolescents, long-term observation of the eye axis and aberration is recommended.
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Chen X, Li Q, Liu L. Personalized Predictive Modeling of Subfoveal Choroidal Thickness Changes for Myopic Adolescents after Overnight Orthokeratology. J Pers Med 2022; 12:jpm12081316. [PMID: 36013265 PMCID: PMC9410041 DOI: 10.3390/jpm12081316] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/09/2022] [Accepted: 08/13/2022] [Indexed: 11/16/2022] Open
Abstract
The changes in subfoveal choroidal thickness after orthokeratology are crucial in myopia retardation; this study aimed to identify the risk factors that could be incorporated into a predictive model for subfoveal choroidal thickness (SFChT) that would provide further personalized and clinically specific information for myopia control. A one-year prospective study was conducted in the West China Hospital, Sichuan University. Basic information (age, gender, and height) was collected from all subjects. Initial spherical equivalent, axial length, intraocular pressure, central corneal thickness, and subfoveal choroidal thickness were measured, and the ocular environmental factors were also collected. All the measured parameters were recorded in the follow-up period for one year. After the analysis of univariate analysis, statistically significant factors were substituted into the multivariate three-level model. Thirty-three adolescents aged 8−14 years old were enrolled in this study; the results show that the subfoveal choroidal thickness in both eyes changed significantly after 12 months of lens wearing (pR < 0.0001, pL < 0.0001). The axial length was negatively correlated with the change in the SFChT after 12 months of lens wearing (r = −0.511, p = 0.002). After multilevel model analysis, the statistically significant factor was shown to have an important influence on the changes in the subfoveal choroidal thickness, which was the average near-work time. This suggested that the SFChT personal predictions can be made regarding changes in myopic adolescents after orthokeratology using the factor of daily average near-work time. Clinical practitioners will benefit from the results by obtaining a better understanding of the effects of orthokeratology on choroid and myopia progression.
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Affiliation(s)
- Xiaohang Chen
- Department of Optometry and Visual Science, West China Hospital, Sichuan University, Chengdu 610041, China
- The Laboratory of Optometry and Vision Sciences, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Qiushi Li
- Department of Outpatient, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Longqian Liu
- Department of Optometry and Visual Science, West China Hospital, Sichuan University, Chengdu 610041, China
- The Laboratory of Optometry and Vision Sciences, West China Hospital, Sichuan University, Chengdu 610041, China
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu 610041, China
- Correspondence:
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Ding C, Chen Y, Li X, Huang Y, Chen H, Bao J. The associations of accommodation and aberrations in myopia control with orthokeratology. Ophthalmic Physiol Opt 2021; 42:327-334. [PMID: 34866209 PMCID: PMC9300108 DOI: 10.1111/opo.12930] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 10/20/2021] [Accepted: 10/23/2021] [Indexed: 11/29/2022]
Abstract
Purpose This study aimed to investigate the effect of orthokeratology (OK) on accommodative function and aberrations, to explore the correlations between them and determine what role they play in myopia control. Methods In this prospective case‐controlled study, 61 children were divided into an OK (n = 30) and a single‐vision spectacles (SVS) (n = 31) group. Accommodation and ocular wavefront aberrations in the OK group were measured at baseline and after 1, 3, 6, 9 and 12 months of OK wear, and again at 1 month after stopping OK (13th month). The same procedure was performed in the SVS group at baseline and at 3, 6 and 12 months. Axial length (AL), accommodative lag area and aberrations including spherical aberration (SA), coma and total higher‐order aberrations (HOAs) were analysed. Results During OK wear, the accommodative lag area at each visit was lower than the baseline level (all p < 0.01); all aberrations at each visit were higher than pre‐treatment (all p < 0.001). After 1 month of OK treatment, changes in accommodative lag area and SA did not show significant correlation (p = 0.16), but after OK cessation these changes were correlated (p = 0.01). In the OK group, multivariate regression analysis showed changes in accommodative lag area were associated with AL progression in the first 6 months but not in the 1‐year analysis. For the SVS group, there were no significant changes in the accommodative lag area or any aberrations during the study period. Conclusions Increased HOAs and improved accommodative accuracy were observed during OK treatment, but began to regress after the cessation of OK. A significant positive correlation between improved accommodative accuracy and slowed axial elongation was only observed during the first 6 months of treatment.
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Affiliation(s)
- Chenglu Ding
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.,National Clinical Research Center for Ocular Diseases, Wenzhou, China
| | - Yunyun Chen
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.,National Clinical Research Center for Ocular Diseases, Wenzhou, China
| | - Xue Li
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.,National Clinical Research Center for Ocular Diseases, Wenzhou, China
| | - Yingying Huang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.,National Clinical Research Center for Ocular Diseases, Wenzhou, China
| | - Hao Chen
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.,National Clinical Research Center for Ocular Diseases, Wenzhou, China
| | - Jinhua Bao
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.,National Clinical Research Center for Ocular Diseases, Wenzhou, China
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Li X, Hu Q, Wang QR, Feng ZQ, Yang F, Du CY. Analysis of ocular structural parameters and higher-order aberrations in Chinese children with myopia. World J Clin Cases 2021; 9:8035-8043. [PMID: 34621860 PMCID: PMC8462189 DOI: 10.12998/wjcc.v9.i27.8035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/03/2021] [Accepted: 07/26/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Myopia and high myopia are global public health concerns. Patients with high myopia account for 0.5%-5.0% of the global population.
AIM To examine diopters, axial length (AL), higher-order aberrations, and other ocular parameters in Chinese children with myopia, to analyze the influence of structural parameters associated with myopia on visual quality, and to provide a theoretical basis for the prevention and treatment of childhood myopia and high myopia.
METHODS This study included 195 children aged 6–17 years with myopia. The AL was measured with an ultrasonic ophthalmic diagnostic instrument, and the aberrations, corneal curvature (minimum K1, maximum K2, and average Km), central corneal thickness, anterior chamber depth, and anterior chamber angle were measured using a Sirius three-dimensional anterior segment analyzer. Using a standard formula, the corneal radius of curvature R (337.3/Km) and AL/R values were obtained.
RESULTS The diopter of high myopia compared with low-middle myopia was correlated with age and AL (r = -0.336, -0.405, P < 0.001), and AL of high myopia was negatively correlated with K1, K2, and Km (r = -0.673, -0.661, and -0.680, respectively; P < 0.001), and positively correlated with age and the anterior chamber depth (r = 0.214 and 0.275, respectively; P < 0.05). AL/R was more closely related to diopter than AL in children with myopia, and 94.4% of children with myopia had an AL/R of > 3.00.
CONCLUSION The ocular structural parameters of children change because of different diopters. AL/R is more specific and sensitive than AL in evaluating the refractive status of myopia in children. An AL/R of > 3.00 may be used as a specific index of myopia in children. There are differences in AL/R between high myopia and low-middle myopia, which can be used for the classification of ametropia. The degree of myopia has a certain influence on higher-order aberrations.
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Affiliation(s)
- Xue Li
- Department of Ophthalmology, The Center of Optometry of The First Affiliated Hospital of Harbin Medical University, Harbin 150000, Heilongjiang Province, China
| | - Qi Hu
- Department of Ophthalmology, The Second Hospital of Shanxi Medical University, Taiyuan 030000, Shanxi Province, China
| | - Qian-Ru Wang
- Department of Ophthalmology, Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou 510000, Guangdong Province, China
| | - Zi-Qing Feng
- Department of Ophthalmology, Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou 510000, Guangdong Province, China
| | - Fan Yang
- Department of Ophthalmology, The Center of Optometry of The First Affiliated Hospital of Harbin Medical University, Harbin 150000, Heilongjiang Province, China
| | - Chun-Yu Du
- Department of Ophthalmology, The Center of Optometry of The First Affiliated Hospital of Harbin Medical University, Harbin 150000, Heilongjiang Province, China
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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: 10] [Impact Index Per Article: 3.3] [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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Ruan X, Liu Z, Luo L, Liu Y. The Structure of the Lens and Its Associations with the Visual Quality. BMJ Open Ophthalmol 2020; 5:e000459. [PMID: 33024825 PMCID: PMC7511618 DOI: 10.1136/bmjophth-2020-000459] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 08/22/2020] [Accepted: 08/24/2020] [Indexed: 12/30/2022] Open
Abstract
In humans, the lens is the organ with the ability to change morphology and refractive power, designated as accommodation, to focus light from various distances and obtain clear retinal image. The accommodative ability of the lens depends on its structure and biological parameters. The lens grows throughout the life, forming specific lens sutures and a unique gradient refractive index, and possesses regenerative ability under certain circumstances. Minimally invasive lens surgery that preserves endogenous lens epithelial stem/progenitor cells (LECs) can achieve functional lens regeneration in humans. The lens is the main source of intraocular aberration, especially intraocular higher-order aberrations (IHOAs) which is found to be binocularly symmetrical in phakic eyes. There is a compensation mechanism between corneal aberrations and lens aberrations. Therefore, the structure and the biological parameters of the lens, the binocular relationship of the lens and the correlation between the lens and cornea affect visual quality. This paper summarises the above findings and their current and potential applications in refractive surgeries, providing a comprehensive understanding of the lens as a strong determinant of visual quality in the optical system.
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Affiliation(s)
- Xiaoting Ruan
- State Key Laboratory of Ophthalmology, Sun Yat-Sen University Zhongshan Ophthalmic Center, Guangzhou, China
| | - Zhenzhen Liu
- State Key Laboratory of Ophthalmology, Sun Yat-Sen University Zhongshan Ophthalmic Center, Guangzhou, China
| | - Lixia Luo
- State Key Laboratory of Ophthalmology, Sun Yat-Sen University Zhongshan Ophthalmic Center, Guangzhou, China
| | - Yizhi Liu
- State Key Laboratory of Ophthalmology, Sun Yat-Sen University Zhongshan Ophthalmic Center, Guangzhou, China
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Schachar RA, Schachar IH. Intralenticular Hydrostatic Pressure Increases During Ciliary Muscle Contraction: A Finding Consistent With the Schachar Mechanism of Accommodation. Invest Ophthalmol Vis Sci 2020; 61:34. [PMID: 32543663 PMCID: PMC7415311 DOI: 10.1167/iovs.61.6.34] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 11/18/2019] [Indexed: 12/02/2022] Open
Affiliation(s)
- Ronald A. Schachar
- Department of Physics, University of Texas at Arlington, La Jolla, California, United States
| | - Ira H. Schachar
- Department of Ophthalmology, Horngren Family Vitreoretinal Center, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, California, United States. E-mail:
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Grzybowski A, Schachar RA, Gaca-Wysocka M, Schachar IH, Pierscionek BK. Image registration of the human accommodating eye demonstrates equivalent increases in lens equatorial radius and central thickness. Int J Ophthalmol 2019; 12:1751-1757. [PMID: 31741865 PMCID: PMC6848867 DOI: 10.18240/ijo.2019.11.14] [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: 11/27/2018] [Accepted: 08/03/2019] [Indexed: 11/23/2022] Open
Abstract
AIM To compare the results of in vivo human high resolution image registration studies of the eye during accommodation to the predictions of mathematical and finite element models of accommodation. METHODS Data from published high quality image registration studies of pilocarpine induced accommodative changes of equatorial lens radius (ELR) and central lens thickness (CLT) were statistically analyzed. RESULTS The mean changes in ELR and CLT were 6.76 µm/diopter and 6.51 µm/diopter, respectively. The linear regressions, reflecting the association between ELR and accommodative amplitude (AAELR) was: slope=6.58 µm/diopter, r2 =0.98, P<0.0001 and between CLT and AACLT was: slope=6.75 µm/diopter, r2 =0.83, P<0.001. On the basis of these relationships, the CLT slope and the AAELR were used to predict the measured change in ELR (ELRpredicted). There was no statistical difference between ELRpredicted and the measured ELR as demonstrated by a Student's paired t-test: P=0.96 and linear regression analysis: slope=0.97, r2 =0.98, P<0.00001. CONCLUSION Image registration with invariant positional references demonstrates that ELR and CLT equivalently minimally increase ∼7.0 µm/diopter during accommodation. The small equivalent increases in ELR and CLT are associated with a large accommodative amplitude. These findings are consistent with the predictions of mathematical and finite element models that specified the stiffness of the lens nucleus is the same or greater than the lens cortex and that accommodation involves a small force (<5 g).
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Affiliation(s)
- Andrzej Grzybowski
- Institute for Research in Ophthalmology, Poznan 60-554, Poland
- Department of Ophthalmology, University of Warmia and Mazury, Olsztyn 10-082, Poland
| | - Ronald A Schachar
- Department of Physics, University of Texas in Arlington, Arlington, Texas 76019, USA
| | | | - Ira H Schachar
- Department of Ophthalmology, Horngren Family Vitreoretinal Center, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, California 94304, USA
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Pan X, Lie AL, White TW, Donaldson PJ, Vaghefi E. Development of an in vivo magnetic resonance imaging and computer modelling platform to investigate the physiological optics of the crystalline lens. BIOMEDICAL OPTICS EXPRESS 2019; 10:4462-4478. [PMID: 31565502 PMCID: PMC6757483 DOI: 10.1364/boe.10.004462] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 07/07/2019] [Accepted: 07/12/2019] [Indexed: 05/11/2023]
Abstract
We have developed and validated in vivo magnetic resonance imaging (MRI) protocols to extract parameters (T2 and geometry) of the human lens that, combined with biometric measures of the eye and optical modelling, enable us to investigate the relative contributions made by the gradient of refractive index (GRIN) and the shape of the lens to the refractive properties of each subject tested. Seven young and healthy participants (mean age: 25.6 ± 3.6 years) underwent an ophthalmic examination, and two sessions of MRI scans using a 3 T clinical magnet. Our MRI protocols for studying lens physiological optics and geometrical measurements were repeatable and reliable, using both 1D (95% confidence interval (CI) for mean differences for exponents = [-2.1, 2.6]) and 2D analysis (anterior T2 CI for differences [-6.4, 8.1] ms; posterior T2 CI for differences [-6.4, 8.3] ms). The lens thickness measured from MRI showed good correlation with that measured with clinical 'gold standard' LenStar (mean differences = [-0.18, 0.2] mm). The predicted refractive errors from ZEMAX had reasonable agreements with participants' clinic records (mean differences = [-1.7, 1.2] D). Quantitative measurements of lens geometry and GRIN with our MRI technique showed high inter-day repeatability. Our clinical MRI technique also provides reliable measures of lens geometry that are comparable to optical biometry. Finally, our ZEMAX optical models produced accurate refractive error and lens power estimations.
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Affiliation(s)
- Xingzheng Pan
- School of Optometry and Vision Science, New Zealand National Eye Center, University of Auckland, New Zealand
| | - Alyssa L. Lie
- School of Optometry and Vision Science, New Zealand National Eye Center, University of Auckland, New Zealand
| | - Thomas W. White
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
| | - Paul J. Donaldson
- School of Optometry and Vision Science, New Zealand National Eye Center, University of Auckland, New Zealand
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Center, University of Auckland, New Zealand
| | - Ehsan Vaghefi
- School of Optometry and Vision Science, New Zealand National Eye Center, University of Auckland, New Zealand
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Mechanism of accommodation assessed by change in precisely registered ocular images associated with concurrent change in auto-refraction. Graefes Arch Clin Exp Ophthalmol 2017; 256:395-402. [PMID: 29147767 DOI: 10.1007/s00417-017-3843-2] [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: 05/16/2017] [Revised: 09/27/2017] [Accepted: 11/04/2017] [Indexed: 10/18/2022] Open
Abstract
PURPOSE Our purpose was to determine the changes in anterior chamber depth (ACD) and central lens thickness (CLT) during pharmacologically induced accommodation. METHODS Following pupillary dilation with phenylephrine 10%, baseline auto-refractions and swept-source optical coherence tomographic biometric images (Zeiss IOLMaster 700) were obtained from the right eyes of 25 subjects aged 19 to 24 years. Pilocarpine 4% and phenylephrine 10% were then instilled into these right eyes. One hour later, auto-refractions and biometric imaging were repeated. Only data from eight of 25 subjects met the following stringent criteria to be included in the study analysis: pre and post-pilocarpine biometric foveal images were registerable, the images of the corneal centers were shifted by ≤100 μm, pupils >5 mm and the pharmacologically induced refractive change was ≥ -7 diopters. RESULTS The mean auto-refractive accommodative change for the eight included subjects was -12.45 diopters (± 3.45 diopters). The mean change in CLT was 81 μm (± 54 μm) and the mean change in ACD was -145 μm (± 86 μm). Superimposition of the registered pre and post-pilocarpine biometric images of the sagittal sections of the whole eye from each subject demonstrated that the position of the whole lens did not shift either anteriorly, posteriorly or vertically during pharmacologically induced accommodation. CONCLUSIONS A small increase in lens thickness was associated with a large change in accommodative amplitude and no significant change in lens position as predicted by the Schachar theory.
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