Aqueous humor level of sCD44 in patients with degenerative myopia and primary open-angle glaucoma

BACKGROUND: The transmembrane glycoprotein CD44 is a major hyaluronan cell surface receptor widely distributed in eye tissues and fluids. The shed ectodomain of CD44 is termed soluble CD44 and is toxic to human retinal ganglion cells in cell culture. The purpose of this study was to investigate the concentration of sCD44 in the aqueous humor (AH) of normal subjects, patients with primary open-angle glaucoma, and patients with degenerative myopia but without glaucoma, to determine if the molecule might serve as a protein marker of glaucoma. FINDINGS: In this case-control study, AH samples were collected from controls (n = 16), patients with primary open-angle glaucoma (n = 11), and patients with degenerative myopia (n = 11) who underwent phacoemulsification surgery to treat mature or immature cataracts. The sCD44 concentration in AH was measured using a commercial ELISA kit. In normal AH samples the sCD44 concentration was 5.40 ± 1.21 ng/mL, whereas in degenerative myopia patients the sCD44 concentration was 5.76 ± 1.15 ng/mL. There was thus no statistically significant difference between these two groups (p > 0.05). The aqueous sCD44 concentration in patients with primary open-angle glaucoma (12.2 ± 10.1 ng/mL) was higher than that of the control group (p < 0.05). CONCLUSION: sCD44 may be a protein marker of primary open-angle glaucoma.