Objective: The aim of our study was to compare klotho in the serum and aqueous humor of patients with primary open-angle glaucoma (POAG), pseudoexfoliation glaucoma (PEXG) and pseudoexfoliation syndrome (PEX).

Methods: 18 POAG, 20 PEXG, 19 PEX and 20 control patients were included in our study. Aqueous humor and serum samples were collected at the time of cataract surgery. Samples were collected using enzyme-linked immunosorbent assay to evaluate the levels of Klotho protein.

Results: Klotho levels in the serum and aqueous humor of PEXG patients (34.45 ± 3.59, 0.20 ± 0.15 ng/ml), PEX (35.85 ± 4.26, 0.23 ± 0.20 ng/ml) patients and POAG patients (35.99 ± 3.73, 0.25 ± 0.20 ng/ml) were significantly lower than control group (40.14 ± 3.85, 0.53 ± 0.39 ng/ml) (PEXG, P < 0.001, P < 0.001; PEX, P = 0.002, P = 0.003; POAG, P = 0.006, P = 0.003, respectively). Both serum and aqueous levels of klotho in the PEXG and PEX patients were lower than POAG patients, but the difference did not reach statistical significance (PEXG & POAG P = 0.149, P = 0.696), (PEX & POAG P = 0.845, P = 0.775).

Conclusions: Klotho levels in the serum and aqueous humor decreased in PEX, PEXG and POAG groups compared to control group, but the reduction was most significant in PEXG group.