title: Impedance-based retinal contact imaging as an aid for the placement of high resolution epiretinal prostheses.
abstract: An important factor in effective stimulation of the retina is close contact with the retina. The design of the electrode surface and the placement of the electrode against the retina both affect the degree of contact with the retina. We have addressed the design factor by creating a curved surface 3200-electrode array. The placement factor we have addressed by use of an impedance sensitive feedback from the array. The feedback is in the form of an image showing contact with the retina, where greater pixel intensity indicates greater impedance and thus closer contact with the retina. In this paper, we present qualitative and quantitative assessments of the relationship between impedance and the device output as well as an in vivo demonstration of contact imaging. In addition, we evaluated the three-dimensional profile of the stimulation voltage distribution to assess the importance of close retinal contact for high resolution stimulation.
authors.affiliation: SFA Inc., Onsite Contractor for the Naval Research Laboratory, 4555 Overlook Avenue, Washington, DC 20375, USA. ljohnson@nrl.navy.mil
authors.forename: Lee
authors.initials: L
authors.lastname: Johnson
authors.forename: Dean
authors.initials: D
authors.lastname: Scribner
authors.forename: Perry
authors.initials: P
authors.lastname: Skeath
authors.forename: Richard
authors.initials: R
authors.lastname: Klein
authors.forename: Doug
authors.initials: D
authors.lastname: Ilg
authors.forename: Keith
authors.initials: K
authors.lastname: Perkins
authors.forename: Maxwell
authors.initials: M
authors.lastname: Helfgott
authors.forename: Reginald
authors.initials: R
authors.lastname: Sanders
authors.forename: Dipak
authors.initials: D
authors.lastname: Panigrahi
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D004056:Differential Threshold; D017097:Electric Impedance; D004558:Electric Stimulation / Q000295:instrumentation* / Q000379:methods; D004567:Electrodes, Implanted; D019544:Equipment Failure Analysis; D005074:Evoked Potentials, Visual / Q000502:physiology; D008839:Microelectrodes; D009415:Nerve Net / Q000502:physiology*; D019736:Prostheses and Implants; D015203:Reproducibility of Results; D012160:Retina / Q000502:physiology*; D012680:Sensitivity and Specificity; D013552:Swine