Brain-Derived Neurotrophic Factor in Patients with Primary Open-Angle Glaucoma and Age-related Cataract

Purpose: To study brain-derived neurotrophic factor (BDNF) content in aqueous humor (AH), lacrimal fluid (LF), and blood serum (BS) in patients with age-related cataract and primary open-angle glaucoma (POAG). Methods: BDNF was studied in 57 patients with age-related cataract, 55 patients with POAG combined with cataract, and 29 healthy controls (one eye in each person). AH was sampled during cataract surgery. Results: The levels of BDNF in LF and BS did not differ in cataract patients and controls. The concentration of BDNF (pg/mL) in patients with POAG and cataract was lower than in cataract patients in AH (35.2 +/- 14.2 vs. 54.6 +/- 29.6, P < 0.001), LF (78.0 +/- 25.1 vs. 116.2 +/- 43.1, P < 0.001), and BS (19230 +/- 5960 vs. 22440 +/- 7580, P < 0.02), while the AH/LF ratio was similar (0.46 +/- 0.18 vs. 0.48 +/- 0.19). The AH level of BDNF declined in early POAG and relatively increased in the next stages of the disease, inversely correlating with visual field index (Pearson's correlation coefficient r = -0.404, P = 0.002) and average retinal nerve fiber layer thickness (r = -0.322, P = 0.018). BDNF contents in LF and BS were also the lowest in early POAG. BDNF in AH strongly correlated with its content in LF (r = 0.66, P < 0.000). A formula was suggested to calculate the AH concentration of BDNF basing on its content in LF. Conclusions: BDNF contents are decreased in AH, LF, and BS of patients with POAG demonstrating a significant decrease in the early POAG and relative increase in the next stages of the disease. A strong correlation exists between BDNF contents in AH and LF.