Abstract
Purpose :
Patients with corneal anesthesia are susceptible to corneal injury, scarring and progressive vision loss. Corneal neurotization is a surgical technique that restores corneal sensation using nerve grafts and donor sensory nerves from elsewhere on the face. Further study is needed to investigate factors that mediate nerve growth into the cornea and how nerves derived from other sensory nerves influence the maintenance and healing of the corneal epithelium. Here we present our progress in developing an animal model of corneal neurotization to further explore these questions.
Methods :
Thy1-GFP+ Sprague-Dawley rats, which express green fluorescent protein (GFP) in axons, was used for all studies. Two techniques of corneal denervation were explored: i) transconjuctival ciliary nerve transection, and ii) stereotactic ablation of the ophthalmic nerve. Denervated cornea’s were then harvested and examined for nerve regrowth at 7, 14, and 28 days. In a separate group of animals, the ciliary nerves were exposed to 100% EtOH following transection to further damage axons and prevent regrowth.
Results :
Corneal nerve imaging in the Thy1-GFP+ rat strain with confocal microscopy permitted accurate tracing of stromal and sub-basal corneal nerves (Figure 1A). Following transection of the ciliary nerves, denervation was complete 7 days following injury, however the corneal innervation began to regenerate by 14 days. Topical EtOH following ciliary transection delayed nerve regrowth, however regenerating corneal nerves could be visualized at 28 days (Figure 1B). There were no signs of corneal reinnervation at 14 days following stereotactic ablation of the ophthalmic nerve.
Conclusions :
An animal model of corneal neurotization first necessitates a method of corneal denervation that does not permit nerve regeneration of the corneal innervation. Without such a method, any changes in corneal epithelium cannot be attributed to neurotization but to corneal nerve regrowth. Using stereotactic ablation of the ophthalmic nerve may further delay or prevent corneal nerve regrowth by injuring the corneal nerves more proximally, however longer term studies are required to ensure there is no corneal nerve regrowth past 28 days.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.