title: Extraocular surgery for implantation of an active subretinal visual prosthesis with external connections: feasibility and outcome in seven patients.
abstract: BACKGROUND
  Due to low energy levels in microphotodiode-based subretinal visual prostheses, an external power supply is mandatory. We report on the surgical feasibility and the functional outcome of the extraocular part of an approach to connect a subretinal prosthesis to an extracorporeal connector in the retro-auricular space via a trans-scleral, transchoroidal cable.
  
  
  METHODS
  Seven volunteers with retinitis pigmentosa received an active subretinal implant; energy was supplied by gold wires on a trans-sclerally, transchoroidally implanted polyimide foil leading to the lateral orbital rim where it was fixated and connected to a silicone cable. The cable was implanted subperiostally beneath the temporal muscle using a trocar to the retro-auricular space where it penetrated the skin for connection to a stimulator. To avoid subretinal movement of the implant, three tension relief points have been introduced.
  
  
  RESULTS
  All implantations were performed as planned without complications, and no serious adverse events occurred in the postoperative period. Fixation of the implants was stable throughout the entire study duration of 4 weeks; permanent skin penetration proved to be uncomplicated. Motility was minimally restricted in downgaze and ab-/adduction. Explantation was uneventful.
  
  
  CONCLUSIONS
  The above-described procedure provides a method for stable fixation of a subretinal device with a trans-scleral, transchoroidal cable connection to an extracorporeal connector.
authors.affiliation: Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Besch
authors.forename: H
authors.initials: H
authors.lastname: Sachs
authors.forename: P
authors.initials: P
authors.lastname: Szurman
authors.forename: D
authors.initials: D
authors.lastname: Gülicher
authors.forename: R
authors.initials: R
authors.lastname: Wilke
authors.forename: S
authors.initials: S
authors.lastname: Reinert
authors.forename: E
authors.initials: E
authors.lastname: Zrenner
authors.forename: K U
authors.initials: KU
authors.lastname: Bartz-Schmidt
authors.forename: F
authors.initials: F
authors.lastname: Gekeler
mesh_terms: D024803:Biomedical Enhancement / Q000379:methods*; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D005240:Feasibility Studies; D005451:Fluorescein Angiography / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011474:Prosthesis Design; D019919:Prosthesis Implantation / Q000379:methods*; D012160:Retina / Q000503:physiopathology / Q000601:surgery*; D012174:Retinitis Pigmentosa / Q000175:diagnosis / Q000601:surgery*; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology