NGF and glaucoma: As well, NGF serum levels were significantly lower in early (3.5±0.9 pg/ml, p = 0.0008) and moderate glaucoma groups (3.8±0.7 pg/ml, p<0.0001) but not in the group of advanced glaucoma (5.0±0.7 pg/ml, p = 0.32) when compared to healthy controls (Fig 2).