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

Dr. Ithar Beshtawi's picture
Journal Title, Volume, Page: 
Invest. Ophthalmol. Vis. Sci. March 13, 2014 vol. 55 no. 3 1549-1554
Year of Publication: 
2014
Authors: 
Ithar M. Beshtawi
Optometry Department, Faculty of Medicine and Health Sciences, An-Najah National University, Nablus, Palestine
Current Affiliation: 
Faculty of Medicine and Health Sciences, An-Najah National University, Nablus. Palestine
Riaz Akhtar
Centre for Materials and Structures, School of Engineering, University of Liverpool, Liverpool, United Kingdom
M. Chantal Hillarby
Centre for Regenerative Medicine, Institute of Inflammation and Repair, The University of Manchester, Manchester, United Kingdom
Clare O'Donnell
Optegra Eye Sciences, Optegra Manchester, United Kingdom
Xuegen Zhao
Manchester Materials Science Centre, School of Materials, The University of Manchester, Manchester, United Kingdom
Arun Brahma
Manchester Royal Eye Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester
Fiona Carley
Manchester Royal Eye Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester
Brian Derby
Manchester Materials Science Centre, School of Materials, The University of Manchester, Manchester, United Kingdom
Hema Radhakrishnan
Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
Preferred Abstract (Original): 

Purpose. To explore the biomechanical changes induced by repeated cross-linking using scanning acoustic microscopy (SAM).
Methods. Thirty human corneas were divided into three groups. In group A, five corneas were cross-linked once. In group B, five corneas were cross-linked twice, 24 hours apart. In group C, five corneas were cross-linked three times, 24 hours apart. The contralateral controls in all groups had similar treatment but without UV-A. The speed of sound, which is directly proportional to the square root of the tissue's elastic modulus, was assessed using SAM.
Results. In group A, the speed of sound of the treated corneas was 1677.38 ± 10.70 ms−1 anteriorly and 1603.90 ± 9.82 ms−1 posteriorly, while it was 1595.23 ± 9.66 ms−1 anteriorly and 1577.13 ± 8.16 ms−1 posteriorly in the controls. In group B, the speed of sound of the treated corneas was 1746.33 ± 23.37 ms−1 anteriorly and 1631.60 ± 18.92 ms−1 posteriorly, while it was 1637.57 ± 22.15 ms−1 anteriorly and 1612.30 ± 22.23 ms−1 posteriorly in the controls. In group C, the speed of sound of the treated corneas was 1717.97 ± 18.92 ms−1 anteriorly and 1616.62 ± 17.58 ms−1 posteriorly, while it was 1628.69 ± 9.37 ms−1 anteriorly and 1597.68 ± 11.97 ms−1 posteriorly in the controls. The speed of sound in the anterior (200 × 200 μm) region between the cross-linked and control corneas in groups A, B, and C was increased by a factor of 1.051 (P = 0.005), 1.066 (P = 0.010), and 1.055 (P = 0.005) respectively. However, there was no significant difference among the cross-linked corneas in all groups (P = 0.067).
Conclusions. A significant increase in speed of sound was found in all treated groups compared with the control group; however, the difference among the treated groups is not significant, suggesting no further cross-links are induced when collagen cross-linking treatment is repeated.