title: Vitreal levels of erythropoietin are increased in patients with retinal vein occlusion and correlate with vitreal VEGF and the extent of macular edema.
abstract: OBJECTIVE
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: University Eye Hospital Freiburg, Freiburg, Germany. andreas.stahl@childrens.harvard.edu
authors.forename: Andreas
authors.initials: A
authors.lastname: Stahl
authors.forename: Armin
authors.initials: A
authors.lastname: Buchwald
authors.forename: Gottfried
authors.initials: G
authors.lastname: Martin
authors.forename: Bernd
authors.initials: B
authors.lastname: Junker
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.forename: Lutz L
authors.initials: LL
authors.lastname: Hansen
authors.forename: Hansjurgen T
authors.initials: HT
authors.lastname: Agostini
authors.forename: Lois E H
authors.initials: LE
authors.lastname: Smith
authors.forename: Nicolas
authors.initials: N
authors.lastname: Feltgen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004797:Enzyme-Linked Immunosorbent Assay; D004921:Erythropoietin / Q000378:metabolism*; D005260:Female; D006801:Humans; D008163:Luminescent Measurements; D008269:Macular Edema / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012167:Retinal Perforations / Q000378:metabolism; D012170:Retinal Vein Occlusion / Q000378:metabolism*; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D014822:Vitreous Body / Q000378:metabolism*
chemical_list: C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D004921:Erythropoietin