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Emu ME, Hatami-Marbini H. Planar biaxial testing of CXL strengthening effects. Exp Eye Res 2024; 246:110005. [PMID: 39032624 DOI: 10.1016/j.exer.2024.110005] [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: 04/17/2024] [Revised: 06/07/2024] [Accepted: 07/12/2024] [Indexed: 07/23/2024]
Abstract
The stiffening effect of corneal crosslinking (CXL) treatment, a therapeutic approach for managing the progression of keratoconus, has been primarily investigated using uniaxial tensile experiments. However, this testing technique has several drawbacks and is unable to measure the mechanical response of cornea under a multiaxial loading state. In this work, we used biaxial mechanical testing method to characterize biomechanical properties of porcine cornea before and after CXL treatment. We also investigated the influence of preconditioning on measured properties and used TEM images to determine microstructural characteristics of the extracellular matrix. The conventional method of CXL treatment was used for crosslinking the porcine cornea. The biaxial experiments were done by an ElectroForce TestBench system at a stretch ratio of 1:1 and a displacement rate of 2 mm/min with and without preconditioning. The experimental measurements showed no significant difference in the mechanical properties of porcine cornea along the nasal temporal (NT) and superior inferior (SI) direction. Furthermore, the CXL therapy significantly enhanced the mechanical properties along both directions without creating anisotropic response. The samples tested with preconditioning showed significantly stiffer response than those tested without preconditioning. The TEM images showed that the CXL therapy did not increase the diameter of collagen fibers but significantly decreased their interfibrillar spacing, consistent with the mechanical property improvement of CXL treated samples.
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Affiliation(s)
- Md Esharuzzaman Emu
- Mechanical and Industrial Engineering Department, University of Illinois Chicago, Chicago, IL, USA
| | - Hamed Hatami-Marbini
- Mechanical and Industrial Engineering Department, University of Illinois Chicago, Chicago, IL, USA.
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Shu N, He Y, Zhang Y. Research progress on measurement methods and clinical applications of corneal elastic modulus. Exp Eye Res 2024; 245:109974. [PMID: 38897271 DOI: 10.1016/j.exer.2024.109974] [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: 03/19/2024] [Revised: 06/07/2024] [Accepted: 06/16/2024] [Indexed: 06/21/2024]
Abstract
Various corneal diseases are strongly associated with corneal biomechanical characteristics, and early measurement of patients' corneal biomechanics can be utilized in their diagnosis and treatment. Measurement methods for corneal biomechanical characteristics are classified into ex vivo and in vivo. Some of these methods can directly measure certain corneal biomechanical parameters, while others require indirect calculation through alternative methods. However, due to diversities in measurement techniques and environmental conditions, significant differences may exist in the corneal mechanical properties measured by these two methods. Therefore, comprehensive research on current measurement methods and the exploration of novel measurement techniques may have great clinical significance. The corneal elastic modulus, a critical indicator in corneal biomechanics, reflects the cornea's ability to return to its initial shape after undergoing stress. This review aims to provide a comprehensive summary of the corneal elastic modulus, which is a critical biomechanical parameter, and discuss its direct, indirect, and potential measurement methods and clinical applications.
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Affiliation(s)
- Nanqi Shu
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130041, Jilin Province, China
| | - Yuxi He
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130041, Jilin Province, China
| | - Yan Zhang
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130041, Jilin Province, China; Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, China.
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Zhang X, Jiang J, Kong K, Li F, Chen S, Wang P, Song Y, Lin F, Lin TPH, Zangwill LM, Ohno-Matsui K, Jonas JB, Weinreb RN, Lam DSC. Optic neuropathy in high myopia: Glaucoma or high myopia or both? Prog Retin Eye Res 2024; 99:101246. [PMID: 38262557 DOI: 10.1016/j.preteyeres.2024.101246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 01/17/2024] [Accepted: 01/19/2024] [Indexed: 01/25/2024]
Abstract
Due to the increasing prevalence of high myopia around the world, structural and functional damages to the optic nerve in high myopia has recently attracted much attention. Evidence has shown that high myopia is related to the development of glaucomatous or glaucoma-like optic neuropathy, and that both have many common features. These similarities often pose a diagnostic challenge that will affect the future management of glaucoma suspects in high myopia. In this review, we summarize similarities and differences in optic neuropathy arising from non-pathologic high myopia and glaucoma by considering their respective structural and functional characteristics on fundus photography, optical coherence tomography scanning, and visual field tests. These features may also help to distinguish the underlying mechanisms of the optic neuropathies and to determine management strategies for patients with high myopia and glaucoma.
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Affiliation(s)
- Xiulan Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, 510060, China.
| | - Jingwen Jiang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, 510060, China.
| | - Kangjie Kong
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, 510060, China.
| | - Fei Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, 510060, China.
| | - Shida Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, 510060, China.
| | - Peiyuan Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, 510060, China.
| | - Yunhe Song
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, 510060, China.
| | - Fengbin Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, 510060, China.
| | - Timothy P H Lin
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.
| | - Linda M Zangwill
- Hamilton Glaucoma Center, Viterbi Family Department of Ophthalmology and Shiley Eye Institute, University of California San Diego, La Jolla, CA, USA.
| | - Kyoko Ohno-Matsui
- Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, Tokyo, Japan.
| | - Jost B Jonas
- Department of Ophthalmology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland.
| | - Robert N Weinreb
- Hamilton Glaucoma Center, Viterbi Family Department of Ophthalmology and Shiley Eye Institute, University of California San Diego, La Jolla, CA, USA.
| | - Dennis S C Lam
- The International Eye Research Institute of the Chinese University of Hong Kong (Shenzhen), Shenzhen, China; The C-MER Dennis Lam & Partners Eye Center, C-MER International Eye Care Group, Hong Kong, China.
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