Purpose: To investigate the levels of erythropoietin (EPO) and soluble CD44 (sCD44) in the aqueous and plasma of human eyes with primary open-angle glaucoma (POAG), and to correlate their concentration with severity of glaucoma.
Methods: A total of 30 patients with POAG and 25 patients with senile cataract (control group) of matched age and gender were included in the study prospectively. Aqueous samples were obtained by paracentesis from glaucoma and cataract patients who were undergoing elective surgery. Aqueous and corresponding plasma samples were analysed for EPO and sCD44 concentrations by enzyme-linked immunosorbent assay.
Results: The EPO and sCD44 levels were significantly higher in aqueous of POAG patients with respect to the comparative group of cataract patients (P < 0.001). No significant difference in the levels of EPO and sCD44 in plasma of POAG and cataract patients. A high positive correlation was found between EPO and sCD44 in aqueous of POAG patients (P < 0.001). Significant correlation was found between EPO or sCD44 levels and severity of visual field loss in mild and moderate stages (P < 0.001).
Conclusion: Increased levels of aqueous EPO and sCD44 may be associated with POAG. In addition, EPO and sCD44 may be useful proteins levels in aqueous of POAG patients as a result of glaucoma damage and not a cause. EPO and sCD44 concentrations in aqueous are a possible biomarkers for visual field loss in patients with POAG.