Safety evaluation after LASIK surgery based on the linear creep property: a finite element analysis

AIM: To investigate the effect of the percent tissue altered (PTA) on the safety after laser-assisted in situ keratomileusis (LASIK) based on linear creep characteristics. METHODS: The linear creep characteristics of the cornea were characterized by the generalized Kelvin-Voigt constitutive relation...

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Main Authors: Ji-Xi Guo, Xue-Feng Li, Xin-Chao Wang, Xin-Heng Zhao, Yan Wang, Li-Hua Fang
Format: Article
Language:English
Published: Press of International Journal of Ophthalmology (IJO PRESS) 2025-05-01
Series:International Journal of Ophthalmology
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Online Access:http://ies.ijo.cn/en_publish/2025/5/20250515.pdf
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author Ji-Xi Guo
Xue-Feng Li
Xin-Chao Wang
Xin-Heng Zhao
Yan Wang
Li-Hua Fang
author_facet Ji-Xi Guo
Xue-Feng Li
Xin-Chao Wang
Xin-Heng Zhao
Yan Wang
Li-Hua Fang
author_sort Ji-Xi Guo
collection DOAJ
description AIM: To investigate the effect of the percent tissue altered (PTA) on the safety after laser-assisted in situ keratomileusis (LASIK) based on linear creep characteristics. METHODS: The linear creep characteristics of the cornea were characterized by the generalized Kelvin-Voigt constitutive relationship with five parameters. Then, the displacement and stress distribution on the anterior and posterior surfaces of the cornea were analyzed by constructing the eye model with different PTA. RESULTS: When PTA was above 39%, the vertex displacements under physiological intraocular pressure (IOP, 15 mm Hg) exceeded that of the preoperative glaucoma under average IOP. That is, an excessively high displacement value was found. In addition, with the increase of PTA, the central cornea was stretched thinner and more obviously due to IOP. When PTA was above 39%, the stress at the center of the anterior surface of the residual stroma was more than 20% larger than that of the normal human eye. The residual stroma was forced to stretch more severely due to excessive stress on the anterior surface. This resulted in deformation of the stroma and induced corneal ectasia. Meanwhile, the postoperative vertex displacement increased with the decrease in viscosity ratio. CONCLUSION: PTA less than 39% is the safe range for LASIK surgery. This study may provide a reliable numerical basis for postoperative corneal dilatation and the outcomes after refractive surgery.
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publishDate 2025-05-01
publisher Press of International Journal of Ophthalmology (IJO PRESS)
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spelling doaj-art-4d2deac3104046d592fd54af840df4bf2025-08-20T03:14:58ZengPress of International Journal of Ophthalmology (IJO PRESS)International Journal of Ophthalmology2222-39592227-48982025-05-0118588989610.18240/ijo.2025.05.1520250515Safety evaluation after LASIK surgery based on the linear creep property: a finite element analysisJi-Xi Guo0Xue-Feng Li1Xin-Chao Wang2Xin-Heng Zhao3Yan Wang4Li-Hua Fang5Li-Hua Fang. Key Laboratory for Optoelectronic Information Perception and Instrumentation of Jiangxi Province, Nanchang Hangkong University, Nanchang 330063, Jiangxi Province, China. fanglh71@126.comKey Laboratory for Optoelectronic Information Perception and Instrumentation of Jiangxi Province, Nanchang Hangkong University, Nanchang 330063, Jiangxi Province, ChinaKey Laboratory for Optoelectronic Information Perception and Instrumentation of Jiangxi Province, Nanchang Hangkong University, Nanchang 330063, Jiangxi Province, ChinaTianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Tianjin Eye HospitalTianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Tianjin Eye HospitalKey Laboratory for Optoelectronic Information Perception and Instrumentation of Jiangxi Province, Nanchang Hangkong University, Nanchang 330063, Jiangxi Province, ChinaAIM: To investigate the effect of the percent tissue altered (PTA) on the safety after laser-assisted in situ keratomileusis (LASIK) based on linear creep characteristics. METHODS: The linear creep characteristics of the cornea were characterized by the generalized Kelvin-Voigt constitutive relationship with five parameters. Then, the displacement and stress distribution on the anterior and posterior surfaces of the cornea were analyzed by constructing the eye model with different PTA. RESULTS: When PTA was above 39%, the vertex displacements under physiological intraocular pressure (IOP, 15 mm Hg) exceeded that of the preoperative glaucoma under average IOP. That is, an excessively high displacement value was found. In addition, with the increase of PTA, the central cornea was stretched thinner and more obviously due to IOP. When PTA was above 39%, the stress at the center of the anterior surface of the residual stroma was more than 20% larger than that of the normal human eye. The residual stroma was forced to stretch more severely due to excessive stress on the anterior surface. This resulted in deformation of the stroma and induced corneal ectasia. Meanwhile, the postoperative vertex displacement increased with the decrease in viscosity ratio. CONCLUSION: PTA less than 39% is the safe range for LASIK surgery. This study may provide a reliable numerical basis for postoperative corneal dilatation and the outcomes after refractive surgery.http://ies.ijo.cn/en_publish/2025/5/20250515.pdflaser-assisted in situ keratomileusisfinite elementpercent tissue alteredvertex displacement
spellingShingle Ji-Xi Guo
Xue-Feng Li
Xin-Chao Wang
Xin-Heng Zhao
Yan Wang
Li-Hua Fang
Safety evaluation after LASIK surgery based on the linear creep property: a finite element analysis
International Journal of Ophthalmology
laser-assisted in situ keratomileusis
finite element
percent tissue altered
vertex displacement
title Safety evaluation after LASIK surgery based on the linear creep property: a finite element analysis
title_full Safety evaluation after LASIK surgery based on the linear creep property: a finite element analysis
title_fullStr Safety evaluation after LASIK surgery based on the linear creep property: a finite element analysis
title_full_unstemmed Safety evaluation after LASIK surgery based on the linear creep property: a finite element analysis
title_short Safety evaluation after LASIK surgery based on the linear creep property: a finite element analysis
title_sort safety evaluation after lasik surgery based on the linear creep property a finite element analysis
topic laser-assisted in situ keratomileusis
finite element
percent tissue altered
vertex displacement
url http://ies.ijo.cn/en_publish/2025/5/20250515.pdf
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