title: Extraction of retinal tacks from subjects implanted with an epiretinal visual prosthesis.
abstract: BACKGROUND
  Retinal tacks, first developed for the treatment of complex retinal detachments, have more recently been used for the fixation of epiretinal electrode arrays as part of implanted visual prostheses. Here, we report on the clinical experience of extracting four such tacks after chronic implantation. The ability to safely extract retinal tacks ensures that epiretinal devices can be repositioned or removed if necessary.
  
  
  METHODS
  Custom-built, titanium alloy retinal tacks were mechanically removed from the posterior coats after prolonged implantation (up to 19 months). The resulting wound was characterized by clinical evaluation, fundus photography, and fluorescein angiography while being monitored for stability over time. The wounds were also compared to earlier published reports of the healing response around retinal tacks in human subjects.
  
  
  RESULTS
  Tack extraction was accomplished successfully, without complication, in all four subjects. The wound site was readily identified by pale scar tissue. No change in the wound size or appearance was noted over many months of post-operative observation (up to 22 months after explant). No adverse effects on overall ocular health were detected.
  
  
  CONCLUSIONS
  Extraction of retinal tacks from subjects implanted with epiretinal prostheses can be performed without significant complication. The long-term healing response appears to be stable and localized in eyes afflicted with retinitis pigmentosa or choroideremia. There was also minimal, if any, impact on the local circulatory system. These cases suggest that the use of retinal tacks for anchoring epiretinal visual prostheses does not preclude safe repositioning or removal of the device more than a year after implant.
authors.affiliation: Department of Ophthalmology, School of Medicine, University of California, San Francisco, CA, USA.
authors.forename: Eugene
authors.initials: E
authors.lastname: de Juan
authors.forename: Rand
authors.initials: R
authors.lastname: Spencer
authors.forename: Pierre-Olivier
authors.initials: PO
authors.lastname: Barale
authors.forename: Lyndon
authors.initials: L
authors.lastname: da Cruz
authors.forename: Jordan
authors.initials: J
authors.lastname: Neysmith
mesh_terms: D000368:Aged; D015794:Choroideremia / Q000628:therapy; D020878:Device Removal; D004567:Electrodes, Implanted; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D008297:Male; D008875:Middle Aged; D019919:Prosthesis Implantation; D012160:Retina / Q000601:surgery*; D012174:Retinitis Pigmentosa / Q000628:therapy; D053831:Surgical Fixation Devices; D057488:Visual Prosthesis; D014945:Wound Healing