Purpose: This study compares vitreal levels of erythropoietin (EPO) in patients with retinal vein occlusion (RVO) with control subjects. In addition, it investigates different RVO disease parameters (time of vein occlusion, patient age, vitreal vascular endothelial growth factor (VEGF) levels, and extent of central macular edema) for possible correlations with vitreal EPO levels.
Methods: Serum and vitreal EPO were measured from 6 patients with branch retinal vein occlusion, 6 patients with central retinal vein occlusion, and 12 control subjects (10 macular puckers and 2 macular holes).
Results: Serum EPO levels (9.8 ± 4.9 mU/mL) did not differ between the RVO and control groups and were significantly lower than vitreal EPO levels in all groups. Vitreal EPO was elevated both in branch RVO (91 ± 59 mU/mL) and central RVO (182 ± 70 mU/mL) compared with controls (35 ± 24 mU/mL). Increased vitreal EPO correlated with higher vitreal VEGF (r = 0.64, P = 0.0008) and more pronounced central macular edema (r = 0.66, P = 0.001).
Conclusion: The results from this study indicate that EPO is locally expressed in the retina and that it is upregulated together with VEGF in RVO eyes. Because of its role both in neuroprotection and angiogenesis, ocular EPO might represent an interesting target to investigate in patients with RVO, especially in light of the current anti-VEGF treatments.