title: Development of a surgical approach for a wide-view suprachoroidal retinal prosthesis: evaluation of implantation trauma.
abstract: BACKGROUND
  Our research goal is to develop a safe, reproducible surgical approach for implantation of a wide-field retinal stimulating array. The aim of this study was to evaluate the pathological response to acute implantation of a functional prototype electrode array in the suprachoroidal space.
  
  
  METHODS
  The surgical techniques to implant a 72 platinum electrode array fabricated on 8 × 13 × 0.4 mm polyimide and silicone substrate were developed in a pilot study in anesthetized cats. For the main study, nine eyes were implanted in vivo and unoperated eyes were used as controls. Surgery consisted of a temporal approach with a full-thickness scleral incision 5 mm posterior to the limbus. A suprachoroidal "pocket" was created, the electrode array inserted to sit beneath the area centralis, and placement was confirmed visually. The eyes were collected subsequently for histopathology.
  
  
  RESULTS
  The array was consistently inserted into the suprachoroidal space beneath the area centralis in nine eyes. There was a significant hemorrhage in two cases where implantation was complicated by choroidal congestion. Retinal folding occurred only when the array tip was within 2.6 mm of the optic disc (p < 0.01). There was choroidal incarceration at the incision in six eyes and scleral distortion at the array edges in five. No cases were found where the implant breached the retina, choroid, or sclera.
  
  
  CONCLUSIONS
  A large stimulation array can be reliably inserted into the suprachoroidal space without trauma to the neuroretina. These findings suggest that this is an appropriate surgical approach for the placement of an electrode array for use in retinal stimulation.
authors.affiliation: The Bionic Institute, East Melbourne, VIC, 3002, Australia.
authors.forename: Joel
authors.initials: J
authors.lastname: Villalobos
authors.forename: Penelope J
authors.initials: PJ
authors.lastname: Allen
authors.forename: Mark F
authors.initials: MF
authors.lastname: McCombe
authors.forename: Meera
authors.initials: M
authors.lastname: Ulaganathan
authors.forename: Ehud
authors.initials: E
authors.lastname: Zamir
authors.forename: David C
authors.initials: DC
authors.lastname: Ng
authors.forename: Robert K
authors.initials: RK
authors.lastname: Shepherd
authors.forename: Chris E
authors.initials: CE
authors.lastname: Williams
mesh_terms: D000818:Animals; D002415:Cats; D002829:Choroid / Q000601:surgery*; D004599:Electric Stimulation Therapy / Q000295:instrumentation*; D004567:Electrodes, Implanted; D005110:Extracellular Space; D005131:Eye Injuries / Q000175:diagnosis*; D008839:Microelectrodes; D010865:Pilot Projects; D019919:Prosthesis Implantation; D012160:Retina / Q000293:injuries; D012684:Sensory Thresholds; D014792:Visual Acuity / Q000502:physiology; D057488:Visual Prosthesis