For example, mutations in the genes encoding myocilin [22], and neurotrophin 4 [23] are considered markers for adult-onset glaucoma, while mutations in the genes encoding optineurin [24], and WD repeat-containing protein 36 [25] have no direct link to the pathogenesis of glaucoma, but suggest increased susceptibility of ganglion cells, especially in normal-tension glaucoma. This evidence concerns the gene OPTN and low tension glaucoma.