A SYSTEMATIC OVERVIEW OF THE INCIDENCE OF POSTERIOR CAPSULE OPACIFICATION

Objective: Reported rates of posterior capsule opacification (PCO) var y widely and are based on various definitions of PCO, varying lengths and intervals of follow-up, and the use of different surgical techniqu es, intraocular lens (IOL) designs, and methods of IOL implantation. T his study was designed to obtain a more precise overall estimate of th e incidence of PCO and to explore factors that might influence the rat e of PCO development. Design: A meta-analysis. Methods: Published arti cles 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 s ystematically, and the reported data were abstracted and synthesized u sing the statistical techniques of meta-analysis. Main Outcome Measure : Pooled estimates of the proportion of eyes developing PCO at three p ostoperative timepoints-1 year, 3 years, and 5 years-were measured. Re sults: There is significant heterogeneity among published rates of PCO . The overall pooled estimates (95% confidence limits) of the incidenc e of PCO were 11.8% (9.3%-14.3%) at 1 year, 20.7% (16.6%-24.9%) at 3 y ears, and 28.4% (18.4%-38.4%) at 5 years after surgery. There is no ev idence of a significant decline in PCO incidence during the study peri od. Conclusions: Visually significant PCO develops in more than 25% of patients undergoing standard extracapsular cataract extraction or pha coemulsification with posterior chamber intraocular lens implantation over the first 5 years after surgery. Patient characteristics, surgica l techniques, and differences in research design and reporting may acc ount for some of the variability in reported rates. However, no specif ic factors were identified in the authors' analysis. More precise esti mates of incidence and identification of risk factors for PCO will dep end on the development of a standardized measurement of PCO and wider adoption of more rigorous study methodology.