MT-ND4 and open-angle glaucoma: Total NAD+ in POAG lymphoblasts [mean ± SD: 246 ± 62 nM NAD+/mg protein] was no different to controls [mean ± SD: 214 ± 56 nM NAD+/mg protein; student’s t-test, p = 0.65; Fig 4A], likewise there was no difference in LHON [mean ± SD: 263 ± 32 nM NAD+/mg protein] and age-matched controls [mean ± SD: 217 ± 72 nM NAD+/mg protein; student’s t-test, p = 0.14; Fig 4A].