Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis

Abstract The implementation of intracorneal ring segments (ICRS) is one of the successfully applied refractive operations for the treatment of keratoconus (kc) progression. The different selection of ICRS types along with the surgical implementation techniques can significantly affect surgical outco...

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Autores principales:	Niksa Mohammadi Bagheri, Mahmoud Kadkhodaei, Shiva Pirhadi, Peiman Mosaddegh
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/3dd7196a99a843cbbda7076da0358d95
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spelling	oai:doaj.org-article:3dd7196a99a843cbbda7076da0358d952021-12-02T18:30:58ZEffects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis10.1038/s41598-021-93821-52045-2322https://doaj.org/article/3dd7196a99a843cbbda7076da0358d952021-07-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-93821-5https://doaj.org/toc/2045-2322Abstract The implementation of intracorneal ring segments (ICRS) is one of the successfully applied refractive operations for the treatment of keratoconus (kc) progression. The different selection of ICRS types along with the surgical implementation techniques can significantly affect surgical outcomes. Thus, this study aimed to investigate the influence of ICRS implementation techniques and design on the postoperative biomechanical state and keratometry results. The clinical data of three patients with different stages and patterns of keratoconus were assessed to develop a three-dimensional (3D) patient-specific finite-element model (FEM) of the keratoconic cornea. For each patient, the exact surgery procedure definitions were interpreted in the step-by-step FEM. Then, seven surgical scenarios, including different ICRS designs (complete and incomplete segment), with two surgical implementation methods (tunnel incision and lamellar pocket cut), were simulated. The pre- and postoperative predicted results of FEM were validated with the corresponding clinical data. For the pre- and postoperative results, the average error of 0.4% and 3.7% for the mean keratometry value ( $$\text {K}_{\text{mean}}$$ K mean ) were predicted. Furthermore, the difference in induced flattening effects was negligible for three ICRS types (KeraRing segment with arc-length of 355, 320, and two separate 160) of equal thickness. In contrast, the single and double progressive thickness of KeraRing 160 caused a significantly lower flattening effect compared to the same type with constant thickness. The observations indicated that the greater the segment thickness and arc-length, the lower the induced mean keratometry values. While the application of the tunnel incision method resulted in a lower $$\text {K}_{\text{mean}}$$ K mean value for moderate and advanced KC, the induced maximum Von Mises stress on the postoperative cornea exceeded the induced maximum stress on the cornea more than two to five times compared to the pocket incision and the preoperative state of the cornea. In particular, an asymmetric regional Von Mises stress on the corneal surface was generated with a progressive ICRS thickness. These findings could be an early biomechanical sign for a later corneal instability and ICRS migration. The developed methodology provided a platform to personalize ICRS refractive surgery with regard to the patient’s keratoconus stage in order to facilitate the efficiency and biomechanical stability of the surgery.Niksa Mohammadi BagheriMahmoud KadkhodaeiShiva PirhadiPeiman MosaddeghNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-24 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Niksa Mohammadi Bagheri Mahmoud Kadkhodaei Shiva Pirhadi Peiman Mosaddegh Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis
description	Abstract The implementation of intracorneal ring segments (ICRS) is one of the successfully applied refractive operations for the treatment of keratoconus (kc) progression. The different selection of ICRS types along with the surgical implementation techniques can significantly affect surgical outcomes. Thus, this study aimed to investigate the influence of ICRS implementation techniques and design on the postoperative biomechanical state and keratometry results. The clinical data of three patients with different stages and patterns of keratoconus were assessed to develop a three-dimensional (3D) patient-specific finite-element model (FEM) of the keratoconic cornea. For each patient, the exact surgery procedure definitions were interpreted in the step-by-step FEM. Then, seven surgical scenarios, including different ICRS designs (complete and incomplete segment), with two surgical implementation methods (tunnel incision and lamellar pocket cut), were simulated. The pre- and postoperative predicted results of FEM were validated with the corresponding clinical data. For the pre- and postoperative results, the average error of 0.4% and 3.7% for the mean keratometry value ( $$\text {K}_{\text{mean}}$$ K mean ) were predicted. Furthermore, the difference in induced flattening effects was negligible for three ICRS types (KeraRing segment with arc-length of 355, 320, and two separate 160) of equal thickness. In contrast, the single and double progressive thickness of KeraRing 160 caused a significantly lower flattening effect compared to the same type with constant thickness. The observations indicated that the greater the segment thickness and arc-length, the lower the induced mean keratometry values. While the application of the tunnel incision method resulted in a lower $$\text {K}_{\text{mean}}$$ K mean value for moderate and advanced KC, the induced maximum Von Mises stress on the postoperative cornea exceeded the induced maximum stress on the cornea more than two to five times compared to the pocket incision and the preoperative state of the cornea. In particular, an asymmetric regional Von Mises stress on the corneal surface was generated with a progressive ICRS thickness. These findings could be an early biomechanical sign for a later corneal instability and ICRS migration. The developed methodology provided a platform to personalize ICRS refractive surgery with regard to the patient’s keratoconus stage in order to facilitate the efficiency and biomechanical stability of the surgery.
format	article
author	Niksa Mohammadi Bagheri Mahmoud Kadkhodaei Shiva Pirhadi Peiman Mosaddegh
author_facet	Niksa Mohammadi Bagheri Mahmoud Kadkhodaei Shiva Pirhadi Peiman Mosaddegh
author_sort	Niksa Mohammadi Bagheri
title	Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis
title_short	Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis
title_full	Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis
title_fullStr	Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis
title_full_unstemmed	Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis
title_sort	effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/3dd7196a99a843cbbda7076da0358d95
work_keys_str_mv	AT niksamohammadibagheri effectsofintracornealringsegmentsimplementationtechniqueanddesignoncornealbiomechanicsandkeratometryinapersonalizedcomputationalanalysis AT mahmoudkadkhodaei effectsofintracornealringsegmentsimplementationtechniqueanddesignoncornealbiomechanicsandkeratometryinapersonalizedcomputationalanalysis AT shivapirhadi effectsofintracornealringsegmentsimplementationtechniqueanddesignoncornealbiomechanicsandkeratometryinapersonalizedcomputationalanalysis AT peimanmosaddegh effectsofintracornealringsegmentsimplementationtechniqueanddesignoncornealbiomechanicsandkeratometryinapersonalizedcomputationalanalysis
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Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis

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