title: Evisceration With Injectable Hydrogel Implant in a Rabbit Model.
abstract: OBJECTIVE
  To determine the safety, durability, and biocompatibility of 2.5% polyacrylamide hydrogel (Aquamid, Specialty European Pharma, Ltd., London, UK) as an injectable viscoelastic implant following evisceration in a rabbit model.
  
  
  METHODS
  The protocol was reviewed and approved by the Wake Forest Institutional Animal Care and Use Committee. Adult New Zealand rabbits underwent cornea-sparing evisceration of the right eye with injection of 2.5% polyacrylamide hydrogel implant. The rabbits were sacrificed after 2 weeks (n = 1), 5 weeks (n = 2), 12 weeks (n = 3), 25 weeks (n = 3), and 1 year (n = 3) to evaluate the implant volume and host reaction to the implant. Both eyes were enucleated and their diameters were measured. The eviscerated eyes were fixed in formalin and processed using routine histopathologic methods to assess inflammatory reaction and vascularization.
  
  
  RESULTS
  The implant material was well tolerated with a moderate giant cell reaction seen at 6 weeks that improved over time. Extensive vascularization of the implant was noted starting at 6 weeks. There was excellent maintenance of globe volume that did not diminish over time. The relative diameters of the eviscerated eyes compared with control were 89 ± 6% (mean% ± SD) at 12 weeks (n = 3), 94 ± 2% at 25 weeks (n = 3), and 93 ± 4% at 1 year (n = 3).
  
  
  CONCLUSIONS
  With further study, injectable 2.5% polyacrylamide hydrogel may provide an excellent alternative to solid orbital implants. The implant material was universally well tolerated and maintained appropriate volume in the orbit for the study period of 1 year. Extensive vascularization of the implant was noted indicating biointegration.
authors.affiliation: *Department of Ophthalmology and †Department of Pathology, Wake Forest School of Medicine, Winston-Salem, North Carolina, U.S.A.
authors.forename: Irina V
authors.initials: IV
authors.lastname: Koreen
authors.forename: Elysa A
authors.initials: EA
authors.lastname: McClintic
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Mott
authors.forename: Constance
authors.initials: C
authors.lastname: Stanton
authors.forename: R Patrick
authors.initials: RP
authors.lastname: Yeatts
mesh_terms: D000180:Acrylic Resins / Q000008:administration & dosage*; D000818:Animals; D001672:Biocompatible Materials; D004195:Disease Models, Animal; D017234:Eye Evisceration / Q000379:methods*; D020100:Hydrogels / Q000008:administration & dosage*; D007267:Injections; D009915:Orbit / Q000601:surgery*; D020273:Orbital Implants; D019919:Prosthesis Implantation / Q000379:methods*; D011817:Rabbits
chemical_list: D000180:Acrylic Resins; C486838:Aquamid; D001672:Biocompatible Materials; D020100:Hydrogels