BDNF and open-angle glaucoma: Our study showed no significant differences in BDNF mRNA levels in the blood between POAG patients and controls (P > 0.05), while analysis of the BDNF expression level in correlation with the clinical parameters showed a decrease of mRNA levels with a decrease of the RA value (P = 0.011), which confirms the protective role of BDNF in the development of glaucoma.