Subgroups analysis showed BDNF levels were significantly lower in early (253.8±40.7 pg/ml, p = 0.019) and moderate glaucoma groups (231.3±54.3 pg/ml, p = 0.04) but not in advanced glaucoma group (296.2±103.1 pg/ml, p = 0.06) when compared to the control group (Fig 1). This evidence concerns the gene BDNF and glaucoma.