title: Natural history of central retinal vein occlusion: an evidence-based systematic review.
abstract: OBJECTIVE
  To describe the natural history of central retinal vein occlusion (CRVO) based on the best available evidence from the literature.
  
  
  CONCLUSIONS
  Central retinal vein occlusion is a common sight-threatening retinal vascular disease. Despite the introduction of new interventions, the natural history of CRVO is unclear.
  
  
  METHODS
  Systemic review of all English language articles retrieved using a keyword search of MEDLINE, EMBASE, Current Contents, and the Cochrane Library to November 13, 2008. This was supplemented by hand-searching references of review articles published within the last 5 years. Two investigators independently identified all relevant observational studies evaluating the natural history of RVO and all clinical trials evaluating interventions for CRVO; an untreated control arm was included.
  
  
  RESULTS
  Of 5966 citations retrieved, 53 studies were reviewed, providing 3271 eyes with CRVO for analysis of its natural history. Visual acuity (VA) was generally poor at baseline (<20/40) and decreased further over time. Although 6 studies reported an improvement in VA, none of these improvements resulted in VA better than 20/40. Up to 34% of eyes with nonischemic CRVO converted to ischemic CRVO over a 3-year period. In ischemic CRVO cases, neovascular glaucoma developed in at least 23% of eyes within 15 months. In nonischemic CRVO cases, macular edema resolved in approximately 30% of eyes over time, and subsequent neovascular glaucoma was rare.
  
  
  CONCLUSIONS
  Untreated eyes with CRVO generally had poor VA, which declined further over time. One quarter of eyes with nonischemic CRVO converted to ischemic CRVO.
authors.affiliation: Centre for Eye Research Australia, University of Melbourne, VIC, Australia.
authors.forename: Rachel L
authors.initials: RL
authors.lastname: McIntosh
authors.forename: Sophie L
authors.initials: SL
authors.lastname: Rogers
authors.forename: Lyndell
authors.initials: L
authors.lastname: Lim
authors.forename: Ning
authors.initials: N
authors.lastname: Cheung
authors.forename: Jie Jin
authors.initials: JJ
authors.lastname: Wang
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Kowalski
authors.forename: Hiep P
authors.initials: HP
authors.lastname: Nguyen
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
mesh_terms: D006801:Humans; D012169:Retinal Vein / Q000503:physiopathology; D012170:Retinal Vein Occlusion / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology