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Mekonnen T, Zevallos-Delgado C, Zhang H, Singh M, Aglyamov SR, Larin KV. The lens capsule significantly affects the viscoelastic properties of the lens as quantified by optical coherence elastography. Front Bioeng Biotechnol 2023; 11:1134086. [PMID: 36970614 PMCID: PMC10034121 DOI: 10.3389/fbioe.2023.1134086] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 02/21/2023] [Indexed: 03/11/2023] Open
Abstract
The crystalline lens is a transparent, biconvex structure that has its curvature and refractive power modulated to focus light onto the retina. This intrinsic morphological adjustment of the lens to fulfill changing visual demands is achieved by the coordinated interaction between the lens and its suspension system, which includes the lens capsule. Thus, characterizing the influence of the lens capsule on the whole lens’s biomechanical properties is important for understanding the physiological process of accommodation and early diagnosis and treatment of lenticular diseases. In this study, we assessed the viscoelastic properties of the lens using phase-sensitive optical coherence elastography (PhS-OCE) coupled with acoustic radiation force (ARF) excitation. The elastic wave propagation induced by ARF excitation, which was focused on the surface of the lens, was tracked with phase-sensitive optical coherence tomography. Experiments were conducted on eight freshly excised porcine lenses before and after the capsular bag was dissected away. Results showed that the group velocity of the surface elastic wave, V, in the lens with the capsule intact (V=2.55±0.23 m/s) was significantly higher (p < 0.001) than after the capsule was removed (V=1.19±0.25 m/s). Similarly, the viscoelastic assessment using a model that utilizes the dispersion of a surface wave showed that both Young’s modulus, E, and shear viscosity coefficient, η, of the encapsulated lens (E=8.14±1.10 kPa,η=0.89±0.093 Pa∙s) were significantly higher than that of the decapsulated lens (E=3.10±0.43 kPa,η=0.28±0.021 Pa∙s). These findings, together with the geometrical change upon removal of the capsule, indicate that the capsule plays a critical role in determining the viscoelastic properties of the crystalline lens.
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Affiliation(s)
- Taye Mekonnen
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
| | | | - Hongqiu Zhang
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
| | - Manmohan Singh
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
| | - Salavat R. Aglyamov
- Department of Mechanical Engineering, University of Houston, Houston, TX, United States
| | - Kirill V. Larin
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
- *Correspondence: Kirill V. Larin,
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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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