YKL-40 is a local marker for inflammation in patients with pseudoexfoliation syndrome

To investigate the YKL-40, as a marker of inflammation, in aqueous humor and serum of cataract patients with and without pseudoexfoliation syndrome (PEX). Aqueous humor and serum samples were obtained from 44 patients who underwent phacoemulsification surgery. All patients were divided into two groups: PEX (n = 24) and control (n = 20). YKL-40 levels were measured with enzyme-linked immunosorbent assay (ELISA). The differences between the groups were assessed by using Chi-square and independent sample t-tests. The Pearson correlation coefficient was used to evaluate the correlation between variables. There was a significant difference between the mean YKL-40 levels in the aqueous humor of PEX group (112.0 ± 35.8 ng/mL) and control subjects (88.2 ± 30.6 ng/mL) (P = 0.025). However, the difference between the mean YKL-40 levels in the serum of PEX group (53.5 ± 29.1 ng/mL) and control subjects (44.6 ± 30.2 ng/mL) was non-significant (P = 0.326). The correlation between aqueous humor and serum YKL-40 concentrations was significant in both the groups (r = 0.833, P < 0.001; r = 0.840, P < 0.001, respectively). Increased aqueous humor levels of YKL-40 demonstrate that it is local, but not a systemic marker for inflammation in patients with PEX.