P2RY6 and optic nerve disorder: Shevozaki et al. (2005) showed that P2Y6 lowers IOP – ablation of the P2Y6 gene in mice (P2Y6 KO) results in hypertensive glaucoma–like optic neuropathy—exhibited sustained elevation of IOP, age-dependent damage to the optic nerve, thinning of ganglion cell inner layers, and a reduction of RGC numbers.