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Ithar Beshtawi, Riaz Akhtar, Chantal Hillarby, Clare O'Donnell, Xuegen Zhao, Arun Brahma, Fiona Carley, Brian Derby, Hema Radhakrishnan, Eye and Vision Sciences Research; Biomechanical changes in Human Corneas after Low and High Intensity Collagen Cross-Linking Treatment measured using Scanning Acoustic Microscopy. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3115. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To assess and compare the biomechanical properties of postmortem human corneas after low and high intensity collagen cross-linking using scanning acoustic microscopy (SAM).
Two groups of five human corneal pairs were included in the study. In group (A), five corneas were treated with low intensity cross-linking (epithelium removed, 0.1% riboflavin applied for 30 minutes following which UV-A irradiation (365 nm, 3mW/cm2) was applied for 30 minutes alongside the riboflavin solution) The contralateral cornea was exposed to riboflavin only, and served as a control. In group (B), five corneas were treated with high-intensity collagen cross-linking (epithelium removed, riboflavin 0.1% solution application for 30 minutes prior to UV-A irradiation (365 nm, 9mW/cm2) for 10 minutes, while the riboflavin was re-applied. The contralateral cornea was exposed to riboflavin only, and served as a control. The biomechanical properties of all corneas were tested using SAM.
In the low intensity cross-linked corneas (group A), the speed of sound of the treated corneas was 1674.51 ± 21.38 ms-1 anteriorly and 1598.24 ± 27.83 ms-1 posteriorly, while it was 1593.96 ± 22.51 ms-1 anteriorly and posteriorly 1578.64 ± 18.83 ms-1 in the untreated corneas. In the high-intensity cross-linked corneas (group B), the speed of sound of the treated corneas was 1663.55 ± 20.16 ms-1 anteriorly and 1593.17 ± 20.30 ms-1 posteriorly, while it was 1582.38 ± 15.30 ms-1 anteriorly and 1564.12 ± 18.46 ms-1 posteriorly in the untreated corneas. The speed of sound is directly proportional to the stiffness of the tissue. Therefore the results indicate that corneal stiffness changes are similar in the low and high intensity cross-linking groups.
Scanning acoustic microscopy is a novel tool for examining the biomechanical properties of human corneal tissue. It was used successfully to assess corneal stiffness after applying collagen cross-linking. Similar results were observed in corneas treated with low and high intensity cross-linking protocols.
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