Relation of serum and aqueous humor BDNF levels with retinal nerve fiber layer and ganglion cell complex in patients with and without retinopathy of diabetes mellitus

Purpose: To determine aqueous humor and serum BDNF levels in diabetic patients with and without retinopathy, and to assess the relationship between these factors and RNFL and GCC in the patients. Materials and Methods: BDNF levels in patients' blood and aqueous humor collected during cataract extraction were evaluated with ELISA in diabetic patients without retinopaty, with non-proliferative retinopathy and with proliferative retinopathy. In all groups, RNFL and GCC thicknesses were measured with OCT. Results: Median serum BDNF levels were found to be 485.90 ng / ml (129.25-919.01) in the control group, 367.13 ng / ml (91.72-459.16) in the DM group without retinopathy, 276.55 ng / ml (200.47-641.91) in the non-PDR group and 188.69 ng / ml (102.93-591.79) in the PDR group. The median aqueous humor BDNF levels were 0.81 ng / ml (0.39-1.04) in the control group, 0.62 ng / ml (0.17-0.77) in the DM group without retinopathy, 0.61 ng / ml (0.07-0.71) in the non-PDR group, 0.54 ng / ml (0.07-0.70) in the PDR group (p = 0.002 and p = 0.0016, Kruskal Wallis, respectively). While aqueous humor BDNF levels showed moderate positive correlation with RNFL and GCC levels in all patient groups, serum BDNF levels did not correlate with these parameters. Conclusion: BDNF is reduced in serum and aqueous humor of diabetic patients with and without retinopathy, and this decrease is related to the thinning of the RNFL and GCC layers.