Elevated levels of multiple biomarkers of Alzheimer's disease in the aqueous humor of eyes with open-angle glaucoma

To investigate levels of biomarkers of Alzheimer's disease in the aqueous humor in patients with open-angle glaucoma (OAG). Aqueous humor samples were collected from 38 patients with cataracts, 20 patients with POAG, and 32 patients with exfoliation glaucoma. Aqueous levels of apolipoprotein (Apo) AI, ApoCIII, ApoE, transthyretin (TTR), complement factor H, complement C3, and α2-macroglobulin (α2M) were determined by multiplex bead immunoassay. Clinical data were obtained from medical charts. Age and sex did not differ significantly among groups. POAG patients had significantly higher aqueous levels of Apo AI, ApoCIII, ApoE, TTR, and α2M compared with cataract patients (P < 0.001, P = 0.036, P < 0.001, P < 0.001, and P < 0.001, respectively). Corresponding values for exfoliation glaucoma patients were also significantly higher compared with those for cataract patients (P = 0.003, P = 0.009, P < 0.001, P < 0.001, and P < 0.001), and those levels correlated positively with each other in eyes with OAG (P < 0.001 for all combinations). Complement factor H and complement C3 levels did not differ among groups. Mean deviation values for the Humphrey visual field test correlated positively with levels of Apo AI, ApoE, TTR, and complement factor H in OAG patients (P = 0.026, 0.012, 0.008, and 0.027, respectively), but age and IOP values were not correlated with protein levels. OAG patients had elevated levels of multiple biomarkers of Alzheimer's disease in the aqueous humor.