P2RX7 and glaucoma: Moreover, in models using an increased IOP to induce glaucoma, this activation has been found to be P2X7-dependent [15,16,17,31], and a direct stimulation of P2X7 in the in vivo and ex vivo retina and in primary cultures of microglial cells have been shown to cause morphological change and the upregulation of markers linked to microglial activation [16].