title: Determination of bleb capsule porosity with an experimental glaucoma drainage device and measurement system.
abstract: OBJECTIVE
  Control of intraocular pressure after implantation of a glaucoma drainage device (GDD) depends on the porosity of the capsule that forms around the plate of the GDD.
  
  
  OBJECTIVE
  To compare capsular porosity after insertion of 2 different GDDs using a novel implant and measurement system.
  
  
  METHODS
  We performed an experimental interventional study at an eye research facility in a tertiary eye care center. Testing was performed on 22 adult New Zealand white rabbits that received the experimental GDD or an existing GDD.
  
  
  METHODS
  A new experimental GDD, the Center for Eye Research Australia (CERA) implant, was created using computer-aided design and a 3-dimensional printer. The CERA GDDs were implanted in the eyes of rabbits randomized into 1 of the following 3 groups: with no connection to the anterior chamber (n = 7), with connection to the anterior chamber for 1 week (n = 5), and with connection to the anterior chamber for 4 weeks (n = 5). In a control group (n = 5), a pediatric GDD was implanted without connection to the anterior chamber. We measured the capsular porosity using a pressure-gated picoliter pump at a driving pressure of 12 mm Hg. The animals were killed humanely for histologic study.
  
  
  METHODS
  Porosity of the fibrous capsule around the implant.
  
  
  RESULTS
  We found no difference in mean (SEM) capsular porosity between the CERA (3.39 [0.76; 95% CI, 1.43-5.48] µL/min) and pediatric (4.52 [0.52; 95% CI, 3.19-5.95] µL/min) GDDs (P = .28, unpaired t test) at 4 weeks without aqueous exposure. Mean (SEM) capsular porosity of CERA GDDs connected to the anterior chamber at 1 week was 2.46 (0.36; 95% CI, 1.55-3.44) µL/min but decreased to 0.67 (0.07; 95% CI, 0.49-0.86) µL/min at 4 weeks (P = .001, unpaired t test).
  
  
  CONCLUSIONS
  Our experimental method permits direct measurement of capsular porosity of an in situ GDD. In a comparison between an experimental (CERA) and an existing GDD, no differences were identified in capsular porosity or histologic reaction between the implants. These results suggest that the CERA GDD model can be used to test key components of glaucoma surgery and implant design.
authors.affiliation: Centre for Eye Research Australia, Department of Ophthalmology, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Australia.
authors.forename: Craig
authors.initials: C
authors.lastname: Ross
authors.affiliation: Centre for Eye Research Australia, Department of Ophthalmology, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Australia2Advanced Eye Center, Postgraduate Institute of Medical Education & Research, Chandigarh, India.
authors.forename: Surinder Singh
authors.initials: SS
authors.lastname: Pandav
authors.affiliation: Centre for Eye Research Australia, Department of Ophthalmology, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Australia.
authors.forename: Yu Qin
authors.initials: YQ
authors.lastname: Li
authors.affiliation: Centre for Eye Research Australia, Department of Ophthalmology, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Australia3Department of Ophthalmology, Mid-Cheshire Hospitals NHS Foundation Trust, Leighton, England4Institute for S.
authors.forename: Dan Q
authors.initials: DQ
authors.lastname: Nguyen
authors.affiliation: ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, Australian National Fabrication Facility Materials Node, Australian Institute for Innovative Materials Facility, Innovation Campus, University of Wollongong, Wo.
authors.forename: Stephen
authors.initials: S
authors.lastname: Beirne
authors.affiliation: ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, Australian National Fabrication Facility Materials Node, Australian Institute for Innovative Materials Facility, Innovation Campus, University of Wollongong, Wo.
authors.forename: Gordon G
authors.initials: GG
authors.lastname: Wallace
authors.affiliation: Glaucoma Sector, Service d'ophtalmologie, Hôpitaux Universitaires de Genève, Geneva, Switzerland.
authors.forename: Tarek
authors.initials: T
authors.lastname: Shaarawy
authors.affiliation: Centre for Eye Research Australia, Department of Ophthalmology, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Australia.
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Crowston
authors.affiliation: Centre for Eye Research Australia, Department of Ophthalmology, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Coote
mesh_terms: D000818:Animals; D001082:Aqueous Humor / Q000502:physiology*; D001672:Biocompatible Materials; D003228:Conjunctiva / Q000601:surgery*; D004195:Disease Models, Animal; D004867:Equipment Design; D020327:Glaucoma Drainage Implants; D007429:Intraocular Pressure / Q000502:physiology; D016062:Porosity; D019919:Prosthesis Implantation; D011817:Rabbits; D019738:Surgically-Created Structures; D013536:Suture Techniques
chemical_list: D001672:Biocompatible Materials