Pathogenesis of glaucomatous optic neuropathy

The previous chapters have discussed many different elements that contribute to glaucoma and glaucomatous optic neuropathy (GON) in particular. This chapter will summarize and explain these different elements into one concept. GON is characterized by two major elements:

• the loss of retinal ganglion cells and their axons (mainly by apoptosis)

• tissue remodelling leading to the characteristic cupping of the optic nerve head (ONH).

One of the major molecules to cause apoptosis is peroxynitrate (ONOO—). Peroxynitrate is produced if nitric oxide (NO) diffuses into axons in which high concentrations of peroxide, due to reperfusion, are present (Figure 8.1). As with peroxynitrate, but unlike NO, peroxide cannot penetrate intact cell membranes. Peroxynitrate, although very reactive with a short half-life, can diffuse to some extent within the axons both in the direction of the lateral ganglion geniculate nucleus, and towards the retina causing damage on both sides (Figure 8.2).