title: Stimulation with a wireless intraocular epiretinal implant elicits visual percepts in blind humans.
abstract: OBJECTIVE
  Electrical stimulation of retinal neurons has been shown to be a feasible way to elicit visual percepts in patients blind from retinal degenerations. The EPIRET3 retinal implant is the first completely wireless intraocular implant for epiretinal stimulation. Stimulation tests have been performed during a clinical trial that was carried out at the eye clinics of Aachen and Essen to evaluate the safety and the efficacy of the implant.
  
  
  METHODS
  Six legally blind retinitis pigmentosa patients were included in the study. In accordance with the regulations laid down in the study protocol, three 1-hour perceptual tests for each subject were performed within 4 weeks of surgery. Stimuli were charge-balanced square current pulses of various durations and current amplitudes.
  
  
  RESULTS
  All subjects reported visual percepts as a result of electrical stimulation by the implant. Thresholds for eliciting visual percepts varied between them but were below the safety limits of electrical stimulation. Stimulation success depended stronger on pulse duration than on current amplitude or total charge delivered. Subjects were able to discriminate between stimulation patterns of different orientations or at different locations of the electrode array.
  
  
  CONCLUSIONS
  The EPIRET3 system is suitable to elicit visual percepts in blind retinitis pigmentosa patients.
authors.affiliation: Department of Neurophysics, Philipps-University Marburg, Marburg, Germany. susanne.klauke@physik.uni-marburg.de
authors.forename: Susanne
authors.initials: S
authors.lastname: Klauke
authors.forename: Michael
authors.initials: M
authors.lastname: Goertz
authors.forename: Stefan
authors.initials: S
authors.lastname: Rein
authors.forename: Dirk
authors.initials: D
authors.lastname: Hoehl
authors.forename: Uwe
authors.initials: U
authors.lastname: Thomas
authors.forename: Reinhard
authors.initials: R
authors.lastname: Eckhorn
authors.forename: Frank
authors.initials: F
authors.lastname: Bremmer
authors.forename: Thomas
authors.initials: T
authors.lastname: Wachtler
mesh_terms: D000328:Adult; D000368:Aged; D001485:Basement Membrane / Q000601:surgery; D001766:Blindness / Q000503:physiopathology* / Q000534:rehabilitation; D004558:Electric Stimulation; D004599:Electric Stimulation Therapy / Q000295:instrumentation*; D004567:Electrodes, Implanted; D004869:Equipment Safety; D005260:Female; D006801:Humans; D008297:Male; D008839:Microelectrodes; D008875:Middle Aged; D011446:Prospective Studies; D019736:Prostheses and Implants; D012160:Retina / Q000503:physiopathology* / Q000601:surgery; D012174:Retinitis Pigmentosa / Q000503:physiopathology* / Q000534:rehabilitation; D014796:Visual Perception / Q000502:physiology*; D059015:Wireless Technology / Q000295:instrumentation