title: Experimental evaluation of a hydroxylapatite reservoir tube shunt in rabbits.
abstract: OBJECTIVE
  Anterior chamber tube shunts of various design are of increasing importance in the surgical management of refractory glaucoma. However, the reservoirs that are commonly used today are made of a silicone or an acrylic material that may become enveloped by a fibrous capsule, which in turn may impede aqueous resorption. In this study, the authors investigated the properties of hydroxylapatite (HA) as a reservoir in gonioimplants, using three different types of HA reservoir designs. It has been demonstrated that HA orbital implants become vascularized, and the authors hypothesized that this feature of HA might modify the development of the fibrous capsule, enhancing the efficacy and decreasing the size of the implants.
  
  
  METHODS
  HA reservoirs with Silastic tube shunts were implanted in the right eyes of six Dutch-belted rabbits. Clinical examinations were performed and intraocular pressure was measured periodically for 16 weeks postoperatively. Prior to euthanasia, fluorescein-labeled latex microspheres were injected into the anterior chamber to demonstrate implant patency. Light microscopy was used to study the tissue response to the implants and the pathways of aqueous flow.
  
  
  RESULTS
  In general, the authors found a granulomatous inflammatory response to the HA accompanied by neovascularization into the implant and minimal fibrous encapsulation of the reservoir.
  
  
  CONCLUSIONS
  The use of HA as a suprascleral reservoir has several advantages, the major one being a theoretical increase in the functional lifetime of the implant.
authors.affiliation: Department of Ophthalmology, School of Medicine, University of North Carolina, Chapel Hill 27589-7040, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Pandya
authors.forename: C
authors.initials: C
authors.lastname: Rich
authors.forename: D E
authors.initials: DE
authors.lastname: Eifrig
authors.forename: J
authors.initials: J
authors.lastname: Hanker
authors.forename: R L
authors.initials: RL
authors.lastname: Peiffer
mesh_terms: D000818:Animals; D000867:Anterior Chamber / Q000601:surgery; D001672:Biocompatible Materials; D017886:Durapatite; D004867:Equipment Design; D007429:Intraocular Pressure; D018465:Molteno Implants; D011817:Rabbits
chemical_list: D001672:Biocompatible Materials; D017886:Durapatite