title: A systematic overview of the incidence of posterior capsule opacification.
abstract: OBJECTIVE
  Reported rates of posterior capsule opacification (PCO) vary widely and are based on various definitions of PCO, varying lengths and intervals of follow-up, and the use of different surgical techniques, intraocular lens (i.o.l.) designs, and methods of IOL implantation. This study was designed to obtain a more precise overall estimate of the incidence of PCO and to explore factors that might influence the rate of PCO development.
  
  
  METHODS
  A meta-analysis.
  
  
  METHODS
  Published articles were selected for study based on a computerized MEDLINE search of the literature and a manual search of the bibliographies of relevant articles. Articles meeting selected inclusion criteria were reviewed systematically, and the reported data were abstracted and synthesized using the statistical techniques of meta-analysis.
  
  
  METHODS
  Pooled estimates of the proportion of eyes developing PCO at three postoperative timepoints--1 year, 3 years, and 5 years--were measured.
  
  
  RESULTS
  There is significant heterogeneity among published rates of PCO. The overall pooled estimates (95% confidence limits) of the incidence of PCO were 11.8% (9.3%-14.3%) at 1 year, 20.7% (16.6%-24.9%) at 3 years, and 28.4% (18.4%-38.4%) at 5 years after surgery. There is no evidence of a significant decline in PCO incidence during the study period.
  
  
  CONCLUSIONS
  Visually significant PCO develops in more than 25% of patients undergoing standard extracapsular cataract extraction or phacoemulsification with posterior chamber intraocular lens implantation over the first 5 years after surgery. Patient characteristics, surgical techniques, and differences in research design and reporting may account for some of the variability in reported rates. However, no specific factors were identified in the authors' analysis. More precise estimates of incidence and identification of risk factors for PCO will depend on the development of a standardized measurement of PCO and wider adoption of more rigorous study methodology.
authors.affiliation: Division of Preventive Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Schaumberg
authors.forename: M R
authors.initials: MR
authors.lastname: Dana
authors.forename: W G
authors.initials: WG
authors.lastname: Christen
authors.forename: R J
authors.initials: RJ
authors.lastname: Glynn
mesh_terms: D002386:Cataract / Q000453:epidemiology* / Q000209:etiology* / Q000473:pathology; D002387:Cataract Extraction / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D007903:Lens Capsule, Crystalline / Q000473:pathology*; D019654:Lens Implantation, Intraocular / Q000009:adverse effects*; D018918:Phacoemulsification / Q000009:adverse effects; D012307:Risk Factors