title: Evaluation of stimulus parameters and electrode geometry for an effective suprachoroidal retinal prosthesis.
abstract: Several approaches have been proposed for placement of retinal prostheses: epiretinal, subretinal and suprachoroidal. We aimed to systematically evaluate the effectiveness of varying a range of stimulus parameters and electrode geometry for a suprachoroidal electrode array, using cortical evoked responses to monopolar electrical stimulation in cats. Our results indicate that charge thresholds were not dependent on electrode size, pulse widths or position of the return electrode tested, but were dependent on the number of sites stimulated in parallel. Further, we found that the combination of monopolar stimulation with large diameter electrodes, wide pulse widths and parallel stimulation minimized the voltage requirements for stimulation. These results provide useful insights for the design specifications of a low voltage suprachoroidal stimulator.
authors.affiliation: The Bionic Ear Institute, Daly Wing, St Vincent's Hospital, VIC-3065, Australia. mshivdasani@bionicear.org
authors.forename: Mohit N
authors.initials: MN
authors.lastname: Shivdasani
authors.forename: Chi D
authors.initials: CD
authors.lastname: Luu
authors.forename: Rosemary
authors.initials: R
authors.lastname: Cicione
authors.forename: James B
authors.initials: JB
authors.lastname: Fallon
authors.forename: Penny J
authors.initials: PJ
authors.lastname: Allen
authors.forename: James
authors.initials: J
authors.lastname: Leuenberger
authors.forename: Gregg J
authors.initials: GJ
authors.lastname: Suaning
authors.forename: Nigel H
authors.initials: NH
authors.lastname: Lovell
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 / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D011474:Prosthesis Design; D012160:Retina / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*