The overall thickness (global RNFL) was reduced significantly in cases homozygous for the risk allele compared to cases with the non-risk allele (p = 0.03; mean (SD): C = 58.3 (8.2) μm, A = 67.9 (12.4) μm; Table 2), consistent with the hypothesis that SIX6 may increase POAG susceptibility via changes in the neural retina. Here, SIX6 is linked to open-angle glaucoma.