title: Collateral vessel presence in branch and central retinal vein occlusions and their impact on visual acuity and anatomical gains: a retrospective analysis.
abstract: OBJECTIVE
  To evaluate the incidence of collateral vessel formation and to determine their impact on best-corrected visual acuity and central foveal thickness in patients with branch or central retinal vein occlusion (BRVO, CRVO) receiving 0.3 mg or 0.5 mg of ranibizumab, or sham.
  
  
  METHODS
  This retrospective analysis was performed in patients with macular edema secondary to retinal vein occlusion who received 6 monthly intravitreal injections of ranibizumab (0.3 mg or 0.5 mg), or sham, followed by 6 months of as-needed treatment. Collateral vessel presence, change from baseline best-corrected visual acuity, and change from baseline central foveal thickness were assessed at baseline and months 3, 6, 9, and 12.
  
  
  RESULTS
  At month 12, 19.6% of BRVO patients receiving sham/0.5 mg and 16.7% receiving ranibizumab (0.3 mg and 0.5 mg pooled) manifested collaterals at the disk, whereas 48.2% and 47.2% displayed collaterals within the retina, respectively. In CRVO patients, 57.9% and 59.2% of all groups manifested collaterals on the disk, respectively, whereas 12.1% and 15.1% displayed collaterals within the retina. Mean best-corrected visual acuity gain in ranibizumab-treated BRVO and CRVO patients was similar, irrespective of collaterals within the retina (
  P > 0.05; CRVO: P > 0.05).
  
  
  CONCLUSIONS
  The location of collaterals differed between retinal vein occlusion subtypes and ranibizumab treatment did not affect collateral vessel incidence. The presence of collaterals did not seem to impact best-corrected visual acuity gains at month 12 in both BRVO and CRVO patients receiving ranibizumab, whereas generally greater central foveal thickness reductions were observed with presence of collaterals in BRVO patients.
authors.affiliation: *Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio; †Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio; and ‡Genentech Inc, South San Francisco, California.
authors.forename: Rishi P
authors.initials: RP
authors.lastname: Singh
authors.forename: Tamara J
authors.initials: TJ
authors.lastname: Lee
authors.forename: Linda
authors.initials: L
authors.lastname: Yau
authors.forename: Roman G
authors.initials: RG
authors.lastname: Rubio
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D020533:Angiogenesis Inhibitors / Q000627:therapeutic use; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use; D004311:Double-Blind Method; D005260:Female; D005584:Fovea Centralis / Q000473:pathology; D006801:Humans; D008269:Macular Edema / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D000069579:Ranibizumab; D012170:Retinal Vein Occlusion / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology
chemical_list: D020533:Angiogenesis Inhibitors; D061067:Antibodies, Monoclonal, Humanized; D000069579:Ranibizumab