title: Ocular biocompatibility testing of intraocular lenses: a 1 year study in pseudophakic rabbit eyes.
abstract: OBJECTIVE
  To evaluate the appropriate duration for conducting ocular biocompatibility studies with an intraocular lens (IOL) in the pseudophakic rabbit model.
  
  
  METHODS
  Alcon Laboratories, Inc., Fort Worth, Texas, USA.
  
  
  METHODS
  A single-piece biconvex poly(methyl methacrylate) (PMMA) IOL was implanted in the capsular bag of 18 eyes of New Zealand white rabbits; 8 eyes received sham surgeries. Rabbits were monitored clinically and then sacrificed 6 or 12 months after surgery for histopathological examination of ocular tissues.
  
  
  RESULTS
  Biomicroscopic examination revealed mild ocular changes in all surgical eyes during the first 3 months postoperatively. After that, there was a high incidence of posterior synechias, flare, and posterior capsule opacification (PCO) in eyes with PMMA IOLs. Posterior synechias and flare scores remained mild to moderate throughout the study, whereas PCO severity increased over time. Similar findings were observed in sham eyes. In addition, several eyes with PMMA IOLs developed IOL dislocation, hyphema, iris bombe, and a fibrous membrane covering the IOL. No discernible differences in biomicroscopic scores were observed in eyes at 6 or 12 months. Intraocular pressures and morphology of the corneal endothelium were normal in both groups. Results from histopathological analysis of the ocular tissues were consistent with observations from the biomicroscopic examinations.
  
  
  CONCLUSIONS
  The results suggest that IOL implantation studies in the pseudophakic rabbit eye should be conducted for 3 or fewer months. Regulatory guidelines requiring longer ocular implantation studies should be revised to reflect the inherently rapid and extensive ocular response in the rabbit model.
authors.affiliation: Alcon Laboratories, Inc., Texas 76134, USA.
authors.forename: J N
authors.initials: JN
authors.lastname: Norton
authors.forename: T
authors.initials: T
authors.lastname: Kohnen
authors.forename: R B
authors.initials: RB
authors.lastname: Hackett
authors.forename: A
authors.initials: A
authors.lastname: Patel
authors.forename: D D
authors.initials: DD
authors.lastname: Koch
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D004195:Disease Models, Animal; D005260:Female; D005500:Follow-Up Studies; D007903:Lens Capsule, Crystalline / Q000473:pathology* / Q000601:surgery; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008297:Male; D008422:Materials Testing; D019904:Polymethyl Methacrylate; D011183:Postoperative Complications / Q000209:etiology / Q000473:pathology; D019591:Pseudophakia / Q000473:pathology*; D011817:Rabbits
chemical_list: D001672:Biocompatible Materials; D019904:Polymethyl Methacrylate