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Paul Flavahan, Karen McDaid, Sanjay Mantry; A Novel Use for Collagen Cross-Linking: Corneal Graft Host/Donor-Bonding. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1598.
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© ARVO (1962-2015); The Authors (2016-present)
Corneal graft wounds take a very long time to heal. Faster healing could provide better surgical outcomes and shorter recovery periods.<br /> <br /> Collagen cross-linking (CXL) is used to treat keratoconus by forming bonds between adjacent stromal collagen fibres, thereby strengthening the cornea.<br /> <br /> We tested the hypothesis that CXL could be used during corneal graft surgery to form early bonds between host and donor collagen, with an experimental model centred around mock grafts constructed from donated human corneal tissue.
Donated human corneal tissue was treated with 20% ethanol for 40 seconds and the epithelium removed by scraping with a scalpel blade. The tissue was then cut into sections measuring 4mmx3mm. Sections were paired together, and sutured with two 10-0 vicryl sutures to hold their 4mm edges in alignment, acting as mock corneal grafts. In order to facilitate tension measurement across a graft, a looped 6-0 silk suture was placed at each end. Control mock grafts from 3 donated corneas was placed into Eagle's MEM culture medium and incubated for 2 days (N=3). All remaining mock grafts (N=7) underwent CXL using the Dresden protocol (Wollensak G et al, AJO, 2003) with an Avedro CXL machine. The CXL-treated mock grafts were then also placed in Eagle's MEM and incubated for 2 days.<br /> <br /> Following incubation, all mock grafts had their 10-0 sutures cut. All mock grafts that held together were mounted on force transducers. These mock grafts were put under increasing tension until eventually the sections were pulled apart. Labchart software was used to capture the strain data.
2 control mock grafts fell apart immediately upon cutting the 10-0 suture and tolerated no strain. It appears that no bond was formed at the graft interface. One mock graft formed a bond and tolerated up to 400mg of strain. All CXL-treated mock grafts stayed bonded together. The strain tolerated was between 390mg and 900mg with a mean tolerance of 580mg.
The results of our study are consistent with our hypothesis that CXL treatment can be used to form early bonds between separate sections of corneal tissue. These were stronger than those formed in the absence of CXL treatment when, in the majority of cases, no bond was formed at all. This has positive implications for corneal graft surgery but further study is required.
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