C3 and glaucoma: Many factors are associated with increased risk of glaucoma, such as increased glutamate levels in human glaucomatous retina [3], visualized [4] as a cloud of glutamate over the RGC layer in experimental models of glaucoma [5], a greater ratio of inflammatory T cells [6] and an increased ratio of complement C3a to C3 [7], and the possibility of an age-associated down-regulation of the CB1 receptor coupled to G-protein α subtype i/o (Gi/o) signaling system [8].