Erythropoietin levels in aqueous humor of patients with glaucoma

PURPOSE To compare the aqueous concentration of erythropoietin (EPO) in eyes with primary open-angle (POAG), pseudoexfoliative (PXFG), and neovascular (NVG) glaucoma with age-matched eyes with cataracts, and to correlate its concentration with other factors including age, gender, intraocular pressure (IOP), type of glaucoma, and severity of glaucoma. METHODS In this prospective non-randomized comparative study, a total of 26 eyes with cataracts (control group) and 92 glaucomatous eyes (POAG, 40 eyes; PXFG, 26 eyes; NVG, 26 eyes) were enrolled. Aqueous samples (0.1 to 0.2 ml) were obtained during phacoemulsification, trabeculectomy, phacotrabeculectomy, or Ahmed valve glaucoma implants. The aqueous concentration of EPO was measured using an enzyme-linked immunosorbent assay. RESULTS The mean±SEM aqueous level of EPO was statistically significantly higher in eyes with glaucoma (56.7±9.3 mIU/ml) compared to the control group (0.8±0.51 mIU/ml; p<0.001). Eyes with NVG had the highest aqueous level of EPO. Aqueous EPO concentrations remained considerably elevated even in eyes with controlled IOP in all three types of glaucoma. Eyes with PXFG displayed the greatest change in aqueous EPO concentration proportionate to the IOP level. In simple regression analysis, IOP, mean deviation, and the type of glaucoma were the factors that had a statistically significantly positive correlation with the aqueous level of EPO (p=0.011 and <0.001, respectively). Only the type of glaucoma remained statistically significant in the multiple regression analysis (adjusted R(2)=0.278). CONCLUSIONS Compared to the control group, the aqueous humor EPO concentration is increased in eyes with POAG, PXFG, and NVG, both with and without controlled IOP. The aqueous level of EPO was more proportionate to the level of IOP in eyes with PXFG compared to eyes with POAG and NVG.