Tear GDF15 Levels Are Elevated in Primary Open-Angle Glaucoma Patients and Correlate With Aqueous Humor Levels

Abstract

Purpose To determine whether growth differentiation factor 15 (GDF15) is detectable and elevated in tears of patients with primary open-angle glaucoma (POAG) and whether tear GDF15 levels correlate with aqueous humor (AH) GDF15 levels.Methods In a single-center cross-sectional study, we recruited 21 patients undergoing ocular surgery, including patients with moderate to severe POAG undergoing glaucoma or cataract surgery (n = 11) and controls without glaucoma undergoing cataract surgery (n = 10). Demographic data were obtained by chart review. Tear samples were obtained preoperatively using Schirmer strips, and AH samples were obtained from the initial limbal paracentesis during surgery. GDF15 concentrations were quantified using enzyme-linked immunosorbent assay.Results AH GDF15 levels were significantly elevated in POAG samples compared with controls (p = .0057), and this difference remained significant after normalization to total protein (p = .0193). GDF15 was detectable in nearly all tear samples and was significantly higher in POAG patients than in controls (p = .0003), remaining significant after normalization (p = .0022). Raw tear and AH GDF15 levels were not significantly correlated (p = .0736, R2 = 0.1588) but showed significant positive correlation after normalizing to total protein and removing two outliers (p = .0019, R2 = 0.4416).Conclusion Tear GDF15 is detectable and significantly elevated in POAG patients. Tear GDF15 correlates with AH GDF15 after normalization to total protein. These findings suggest the potential of tear GDF15 as a noninvasive molecular biomarker of POAG and highlight the importance of larger studies to validate these findings.