Abstract
Purpose: :
The availability of knockout mouse species provide a highly versatile platform for critically examining the corneal wound healing response. We aimed to develop and characterise the wound healing response in a mouse model of intrastromal femtosecond laser (FSL) keratotomy.
Methods: :
An intrastromal lamellar dissection using a Visumax FSL was performed on 16 wild type mice (C57BL6) . The energy level was optimised at 150nJ. The FSL was programmed to perform a lamellar dissection at 50µM depth without sidecut. The flap was not lifted. Fellow eyes were used as controls. Slit lamp photography and confocal microscopy were performed immediately before the mice were sacrificed 4hrs,1,3 and 7 days post surgery. Corneas were harvested for immunocytochemistry, transmission electron microscopy (TEM) and light microscopy (LM)
Results: :
Confocal microscopy shows an absence of keratocytes in the area immediately surrounding the dissection plane. The dissection plane and individual FSL plasma cavitation bubbles were clearly evident on TEM. There was evidence of Keratocyte cell death along the laser resection plane on TEM. LM revealed the dissection plane at a 20µM depth, although not all epithelial cell layers were intact. Staining for monocytes using antibodies for CD11b showed early migration at the peripheries at 4hrs that increases at 24 hrs and become central in treated corneas. Apoptotic cells were evident on TUNEL assay in the immediate ablation zone at 4 and 24 hrs. Ki67 positive proliferating keratocytes are evident at 3 days and increase by 7 days. Minimal myofibroblast transformation is seen at 1 week.
Conclusions: :
We have demonstrated that FSL lamellar cuts can be effectively performed on mice and that this model exhibits typical signs of the corneal wound healing response. This model could provide a ubiquitous platform in which to study corneal wound healing responses in both wild type and knock-out mice species.The ability to create such a lamellar pocket may be utilised for intrastromal drug delivery.
Keywords: cornea: stroma and keratocytes • wound healing • cornea: basic science