title: Porous polyethylene as a spacer graft in the treatment of lower eyelid retraction.
abstract: OBJECTIVE
  An experimental study was performed to: 1) assess the tolerance and incorporation of porous polyethylene (Medpor) in the posterior lamella of the rabbit lower eyelid; 2) analyze the effect of implant thickness on incorporation; 3) investigate the ability of conjunctiva to grow over vascularized Medpor and; 4) determine the effects of Medpor surface modification on biocompatibility and fibrovascularization.
  
  
  METHODS
  In phase I, 10 rabbit eyelids were operated on to analyze the effects of implant thickness and to develop the surgical technique used in phase II of the study. In phase II, 20 lower eyelids of 10 rabbits received 0.85-mm-thick Medpor grafts, each rabbit receiving both an uncoated implant and one coated with an immobilized collagen.
  
  
  RESULTS
  There were no extrusions in phase II. with a postoperative follow-up from 14 to 17 weeks. Fourteen of 20 eyelids had full-thickness conjunctival incisions or excisions placed over the Medpor implant to determine the growth potential of conjunctiva over a vascularized implant. All but one eyelid showed complete defect coverage, occurring in as little as 3 days. Histopathology indicated complete Medpor fibrovascularization as early as 4 weeks after implantation. Because neither coated nor uncoated implants extruded in phase II, no conclusions can be drawn regarding the efficacy of Medpor surface modification.
  
  
  CONCLUSIONS
  Medpor was well tolerated in this soft tissue application, and it offers advantages over other graft materials.
authors.affiliation: Department of Ophthalmology, National Naval Medical Center, Bethesda, Maryland, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Morton
authors.forename: C
authors.initials: C
authors.lastname: Nelson
authors.forename: Y
authors.initials: Y
authors.lastname: Ikada
authors.forename: V M
authors.initials: VM
authors.lastname: Elner
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D005141:Eyelid Diseases / Q000473:pathology / Q000601:surgery*; D005143:Eyelids / Q000473:pathology / Q000601:surgery*; D011095:Polyethylenes; D016062:Porosity; D019919:Prosthesis Implantation; D011817:Rabbits
chemical_list: D001672:Biocompatible Materials; C084562:Medpor; D011095:Polyethylenes