TLR4 and glaucoma: Retinal microglia upregulate TLR expression as an early response to glaucomatous damage [107], polymorphisms in both TLR2 and TLR4 are risk alleles for glaucoma [108, 109], and deletion of Tlr4 in mice reduces RGC death after optic nerve damage [110] and ischemia-reperfusion [111].