Effects on collagen orientation in the cornea after trephine injury.
OBJECTIVE
Structural changes are well known to occur in the cornea after injury. The aim of this study was to investigate collagen orientation changes in the cornea during a short-term wound healing process.


METHODS
Seven bovine corneas were injured using a penetrating 5 mm biopsy punch and were subsequently organ cultured for up to two weeks. Six uninjured corneas acted as controls. The trephine wounded samples were snap frozen in liquid nitrogen either immediately after injury (0 h) or after 1 or 2 weeks in culture. Control/uninjured samples were snap frozen on arrival (0 h) or after 1 or 2 weeks in culture. Wide angle X-ray diffraction data were collected from each cornea at the UK Synchrotron Radiation Source or at the European Synchrotron Radiation Facility. Data analysis revealed information about collagen orientation and distribution in the corneal stroma during wound healing. For histology, two trephine wounded corneas at 0 h and 1 week and one control/uninjured cornea at 0 h were fixed in 10% neutral buffered formalin and processed for wax embedding. Wax sections were subsequently counterstained with haematoxylin and eosin to observe tissue morphology and the time course of complete re-epithelialization.


RESULTS
Immediately after injury, collagen organization was altered in a small area inside the wound but remained similar to the control/uninjured sample in the remainder of the tissue. After one week, the trephine wounded corneas showed complete re-epithelialization and evidence of swelling while collagen adopted a radial arrangement inside and outside the wound.


CONCLUSIONS
Remarkable changes in collagen fibril orientation were observed in trephine wounded corneas. Orientation changes immediately after wounding are likely to be due to the mechanical deformation of the tissue during the wounding process. However, tissue swelling and changes in collagen orientation at later stages probably reflect the processes of tissue repair. These differences will determine corneal stability and strength following trauma and possibly refractive surgery.
Kamma-Lorger
Christina S
CS
Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Wales, UK.
Hayes
Sally
S
Boote
Craig
C
Burghammer
Manfred
M
Boulton
Michael E
ME
Meek
Keith M
KM
D000818:Animals; D002417:Cattle; D003315:Cornea / Q000378:metabolism / Q000473:pathology*; D065306:Corneal Injuries; D024022:Fibrillar Collagens / Q000648:ultrastructure*; D009924:Organ Culture Techniques; D013997:Time Factors; D014945:Wound Healing; D014950:Wounds, Penetrating / Q000378:metabolism / Q000473:pathology; D014961:X-Ray Diffraction
D024022:Fibrillar Collagens