title: Intravitreal vascular endothelial growth factor concentration and axial length.
abstract: BACKGROUND
  To examine the intravitreal concentration of vascular endothelial growth factor (VEGF) in dependence of the axial length in eyes without intraocular neovascularization.
  
  
  METHODS
  The concentrations of VEGF in vitreous samples and blood samples of patients undergoing pars plana vitrectomy for treatment of idiopathic macular holes or epiretinal membranes were examined using enzyme-linked immunosorbent assay. Axial length was determined by biometry.
  
  
  RESULTS
  The study included 34 patients with macular holes (n = 21) or epiretinal membranes (n = 13) with a mean age of 62.4 ± 10.5 years (range: 35-76 years) and a mean axial length of 24.1 ± 1.8 mm (range: 21.0-29.1 mm). The intravitreal VEGF concentration (mean: 71.0 ± 63.2 pg/mL) was significantly (P < 0.001) lower than the VEGF concentration in the blood (830 ± 585 pg/mL). Both parameters were significantly associated with each other (P = 0.04; correlation coefficient r = 0.35). The intravitreal VEGF concentration was not significantly associated with gender (P = 0.25) or age (P = 0.48). A higher intravitreal VEGF concentration was significantly associated with a shorter axial length (P = 0.025; r = -0.39) or a higher hyperopic refractive error (P = 0.04; r = 0.35). Neither plasma concentration of VEGF nor the ratio of plasma VEGF concentrations to intravitreal VEGF concentration was significantly associated with axial length (P = 0.89 and P = 0.22, respectively) or with refractive error (P = 0.89 and P = 0.26, respectively).
  
  
  CONCLUSIONS
  Intravitreal VEGF concentration decreased with increasing axial length. It suggests a diluting effect in eyes with larger intraocular volume and/or a faster turnover rate of VEGF in axially myopic eyes with vitreous liquefaction.
authors.affiliation: *Department of Ophthalmology of the Civil Aviation Medical College of Peking University, Beijing, China; †Department of Ophthalmology, People's Hospital, Peking University, Beijing, China; Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing, China; and ‡Department of Ophthalmology, Medical Faculty Mannheim of the Ruprecht-Karls-University Heidelberg, Seegartenklinik Heidelberg, Germany.
authors.forename: Qingjun
authors.initials: Q
authors.lastname: Hu
authors.forename: Guohua
authors.initials: G
authors.lastname: Liu
authors.forename: Qing
authors.initials: Q
authors.lastname: Deng
authors.forename: Qiuju
authors.initials: Q
authors.lastname: Wu
authors.forename: Yong
authors.initials: Y
authors.lastname: Tao
authors.forename: Jost B
authors.initials: JB
authors.lastname: Jonas
mesh_terms: D000328:Adult; D000368:Aged; D058452:Axial Length, Eye / Q000033:anatomy & histology*; D001699:Biometry; D004797:Enzyme-Linked Immunosorbent Assay; D019773:Epiretinal Membrane / Q000601:surgery; D006801:Humans; D008875:Middle Aged; D012167:Retinal Perforations / Q000601:surgery; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis*; D014821:Vitrectomy; D014822:Vitreous Body / Q000737:chemistry*
chemical_list: C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A