scholarly journals Biomechanical Changes After Repeated Collagen Cross-Linking on Human Corneas Assessed In Vitro Using Scanning Acoustic Microscopy

2014 ◽  
Vol 55 (3) ◽  
pp. 1549 ◽  
Author(s):  
Ithar M. Beshtawi ◽  
Riaz Akhtar ◽  
M. Chantal Hillarby ◽  
Clare O'Donnell ◽  
Xuegen Zhao ◽  
...  
Keyword(s):  
Acoustic Microscopy ◽  
Cross Linking ◽  
Scanning Acoustic Microscopy ◽  
Biomechanical Changes ◽  
Collagen Cross Linking

Biomechanical Changes of Collagen Cross-Linking on Human Keratoconic Corneas Using Scanning Acoustic Microscopy

2015 ◽  
pp. 1-7 ◽  
Author(s):  
Ithar M. Beshtawi ◽  
Riaz Akhtar ◽  
M. Chantal Hillarby ◽  
Clare O’Donnell ◽  
Xuegen Zhao ◽  
...  
Keyword(s):  
Acoustic Microscopy ◽  
Cross Linking ◽  
Scanning Acoustic Microscopy ◽  
Biomechanical Changes ◽  
Collagen Cross Linking

scholarly journals Reevaluating the Effectiveness of Corneal Collagen Cross-linking and Its True Biomechanical Effect in Human Eyes

2017 ◽  
Vol 6 (1) ◽  
pp. 34-41
Author(s):  
Damien Gatinel
Keyword(s):  
Diagnostic Tools ◽  
Cross Linking ◽  
Corneal Rigidity ◽  
Biomechanical Changes ◽  
Biomechanical Effect ◽  
Human Eyes ◽  
Collagen Cross Linking ◽  
Corneal Collagen

ABSTRACT The induction of cross-links in corneal tissue appears to be a promising technique to increase its stiffness and this has been the basis of treatment of keratoconus (KC) and corneal ectatic disease. However, there exists a striking discrepancy between the reported biomechanical effects of corneal collagen cross-linking (CXL) in vitro compared to in vivo, and this has not received much attention in the literature. Despite the documentation of an increase in corneal stiffness in vitro by many investigators, reports that provide evidence of measurable and consistent biomechanical changes in corneal rigidity in vivo after CXL are lacking. Indeed, the absence of documented in vivo biomechanical improvement in CXL-treated corneas is a conundrum, which needs to be further explored. To explain this discrepancy, it has been postulated that biomechanical changes induced by CXL are too subtle to be measured by currently available diagnostic tools or have characteristics not discernible by these technologies. However, the dynamic bidirectional applanation device (Ocular Response Analyzer) and dynamic Scheimpflug analyzer instruments (Corvis ST) have demonstrated the ability to quantify even subtle biomechanical differences in untreated KC corneas of different ectatic degree, and document the reduction in corneal hysteresis (CH) and corneal resistance factor (CRF) in situations where the corneal stiffness is reduced, such as after laser in situ keratomileusis and surface ablation procedures. It has also been possible to demonstrate an altered CH and CRF in patients with diabetes, smoking habit, glaucoma, Fuchs’ dystrophy, and corneal edema. It is puzzling that these diagnostic tools could document subtle biomechanical changes in these situations, yet fail to measure the purported changes induced by CXL on corneas with progressive KC. This failure to document significant and consistent biomechanical changes in corneal rigidity could suggest that CXL does not induce a simple reversal of the particular biomechanical deficits that characterize KC, or make the cornea significantly more resistant to bending forces as has been widely postulated. The absence of measurable biomechanical change in living KC corneas after CXL could be a consequence of biomechanical strengthening which is insignificant compared to the marked weakening caused by preexisting alteration of the collagen structure, disorganization of collagen fiber intertwining, and compromised structural–mechanical homogeneity that are hallmarks of keratoconic disease, especially in corneas with progressive KC. The changes in the cornea induced by CXL that have been described in vivo may instead be driven by a wound healing process in response to the removal of the corneal epithelial layer and subsequent exposure to riboflavin and ultraviolet-A (UVA). This paper will present evidence that sustains this hypothesis. How to cite this article Gatinel D. Reevaluating the Effect­iveness of Corneal Collagen Cross-linking and Its True Biomechanical Effect in Human Eyes. Int J Kerat Ect Cor Dis 2017;6(1):34-41.

Structural and Biomechanical Effects of Photooxidative Collagen Cross-Linking with Photosensitizer Riboflavin and 370 nm UVA Light on Human Corneoscleral Tissues

2013 ◽  
Vol 19 (5) ◽  
pp. 1334-1340 ◽  
Author(s):  
Samjin Choi ◽  
Jae-Ho Shin ◽  
Youjin Cheong ◽  
Kyung-Hyun Jin ◽  
Hun-Kuk Park
Keyword(s):  
Adhesion Force ◽  
Cross Linking ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Uva Light ◽  
Stromal Edema ◽  
Biomechanical Changes ◽  
Collagen Cross Linking

AbstractThis study quantitatively investigated the immediate effects of a photooxidative collagen cross-linking treatment with photosensitizer riboflavin (RF) and 370 nm UVA light in in vitro human corneoscleral collagen fibrils using histology, thickness, scanning electron microscopy, and atomic force microscopy analyses. Twenty 8 × 2 mm corneoscleral strips were dissected sagittally from donor tissue using a scalpel. Four parameters were investigated, including the density, thickness, adhesion force, and stiffness of corneoscleral tissues before and after the collagen cross-linking treatment. The RFUVA-catalyzed collagen cross-linking treatment led to an increase in the density of both corneal (8%) and scleral (23%) stromal collagens. However, there was no difference in corneoscleral thickness. Furthermore, RFUVA-catalyzed collagen cross-linking treatment led to an increased biomechanical response of corneosclera: 25 and 8% increases in corneoscleral stiffness, and 24 and 22% increases in corneoscleral adhesion force. The collagen cross-linking treatment through RF-sensitized photoreaction may cause structural and biomechanical changes in the collagen fibril network of the cornea and the sclera. This is due to narrowing of the interfibrillar spacing and the stromal edema.

Corneal biomechanical outcome of collagen cross-linking in keratoconic patients evaluated by Corvis ST

2020 ◽  
pp. 112067212094479
Author(s):  
Mahmoud Jabbarvand ◽  
Zahra Moravvej ◽  
Kianoush Shahraki ◽  
Hessam Hashemian ◽  
Hamed Ghasemi ◽  
...  
Keyword(s):  
Amplitude Ratio ◽  
Corneal Thickness ◽  
Case Series ◽  
Cross Linking ◽  
Corvis St ◽  
Significant Difference ◽  
Biomechanical Changes ◽  
The Mean ◽  
Prospective Case Series ◽  
Collagen Cross Linking

Purpose: A 6-month evaluation of the topographic and biomechanical changes induced by corneal collagen cross-linking (CXL) in keratoconic eyes using Pentacam and Corvis ST. Design: Longitudinal prospective case series. Methods: In this study, 67 eyes of 67 patients with progressive keratoconus (KCN) treated with “Epithelium-off” CXL were evaluated. Patients with stages 1 or 2 of KCN and a corneal thickness of at least 400 μm at the thinnest point were included. Standard ophthalmologic examinations were carried out for all patients. The topographic and biomechanical measurements of the cornea were obtained by Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany) and Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) preoperatively and 6-month postoperatively. Results: The mean age of the participants was 21.68 ± 4.23 years. There was significant difference in mean spherical equivalent (SE) before and 6 months after CXL. Uncorrected and best corrected visual acuity improved postoperatively, although not statistically significant. The mean and maximum keratometry showed a significant decrease 6 months after CXL (0.93 ± 0.38 D and 1.43 ± 0.62 D, respectively p < 0.001). Among Corvis ST parameters, first applanation length and velocity (AL1 and AV1) showed statistically significant changes. The radius at highest concavity changed significantly (0.13 ± 0.37 mm mean increase after CXL; p < 0.001). A significant increase was observed in stiffness parameter A1 (SP-A1; p < 0.001) and significant decreases were noted in integrated radius (IR) and deformation amplitude ratio (DAR; p < 0.001). Conclusion: Analyzing biomechanical changes after corneal cross-linking can provide basis for efficient KCN treatment. Corvis ST parameters demonstrated changes in corneal biomechanical characteristics indicative of stiffing after CXL.

Clinical and Corneal Biomechanical Changes After Collagen Cross-Linking With Riboflavin and UV Irradiation in Patients With Progressive Keratoconus

Cornea ◽  
2012 ◽  
Vol 31 (6) ◽  
pp. 609-614 ◽  
Author(s):  
Yakov Goldich ◽  
Arie L. Marcovich ◽  
Yaniv Barkana ◽  
Yossi Mandel ◽  
Ami Hirsh ◽  
...  
Keyword(s):  
Uv Irradiation ◽  
Cross Linking ◽  
Biomechanical Changes ◽  
Collagen Cross Linking

Collagen cross-linking: Lysyl oxidase dependent synthesis of pyridinoline in vitro: Confirmation that pyridinoline is derived from collagen

1982 ◽  
Vol 108 (4) ◽  
pp. 1546-1550 ◽  
Author(s):  
Robert C. Siegel ◽  
Joseph C.C. Fu ◽  
Norihiko Uto ◽  
Kentaro Horiuchi ◽  
Daisaburo Fujimoto
Keyword(s):  
Lysyl Oxidase ◽  
Cross Linking ◽  
Collagen Cross Linking
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