Primary open-angle glaucoma (POAG) is an age-related optic neuropathy characterised by the death of retinal ganglion cells (RGCs) and irreversible visual field loss. The disease is commonly progressive, and is often, but not always, associated with raised intraocular pressure.

The precise mechanism of damage in glaucoma is poorly understood with several competing published theories (Fechtner and Weinreb 1994); however generally all theories agree that there is some physical or biochemical event which takes place at the optic nerve head, damaging RGC axons. The RGC axons then degrade along their length within the retinal nerve fibre layer (RNFL), ultimately leading to death of the RGC by apoptosis (Quigley 1998).