title: Mathematical model to predict the need for neodymium: YAG capsulotomy based on posterior capsule opacification rate.
abstract: OBJECTIVE
  To evaluate a model to project the estimated time required before patients having primary phacoemulsification require neodymium:YAG (Nd:YAG) laser capsulotomy.
  
  
  METHODS
  Eleven private practices in the United States.
  
  
  METHODS
  Projections of time to capsulotomy were based on assessment of the early development of posterior capsule opacification (PCO) over time. The PCO data were collected during a clinical study to evaluate MDX-RA, an investigational immunotoxin designed to limit epithelial cell growth, preventing postsurgical PCO. From the PCO data, the estimated time to Nd:YAG capsulotomy in a placebo-treated group was compared with the actual time to capsulotomy in a cohort of patients from general practice who had had phacoemulsification.
  
  
  RESULTS
  By 6 months, the mean Opacification Index in the MDX-RA group was significantly lower than that in the placebo group (P < .05) and it remained significantly lower at 12 (P < .001), 18 (P < .001), and 24 (P < .016) months. The rate of PCO in the MDX-RA group was approximately 6 times lower than that in the placebo group (P < .0004). Fifty-seven percent in the placebo group and 4% in the MDX-RA group were projected to require an Nd:YAG capsulotomy within 3 years of primary cataract surgery. Projected values for the placebo group were similar to actual values observed in the population-based cohort.
  
  
  CONCLUSIONS
  This technique could be used to predict the need for Nd:YAG capsulotomy using early measurements of PCO.
authors.affiliation: Medarex, Annandale, New Jersey 08801-0953, USA.
authors.forename: D S
authors.initials: DS
authors.lastname: Clark
authors.forename: M F
authors.initials: MF
authors.lastname: Munsell
authors.forename: J M
authors.initials: JM
authors.lastname: Emery
mesh_terms: D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D002386:Cataract / Q000209:etiology* / Q000473:pathology / Q000517:prevention & control; D015331:Cohort Studies; D004847:Epithelial Cells / Q000276:immunology; D005260:Female; D006801:Humans; D000922:Immunotoxins / Q000627:therapeutic use; D053685:Laser Therapy; D007903:Lens Capsule, Crystalline / Q000187:drug effects / Q000473:pathology / Q000601:surgery*; D019654:Lens Implantation, Intraocular; D007908:Lens, Crystalline / Q000276:immunology; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D018918:Phacoemulsification / Q000009:adverse effects; D012276:Ricin / Q000627:therapeutic use; D013997:Time Factors
chemical_list: D000911:Antibodies, Monoclonal; D000922:Immunotoxins; D012276:Ricin