title: Surgical feasibility and biocompatibility of wide-field dual-array suprachoroidal-transretinal stimulation prosthesis in middle-sized animals.
abstract: OBJECTIVE
  To investigate the safety and efficacy of a newly-developed wide-field dual-array suprachoroidal-transretinal stimulation (STS) prosthesis in middle-sized animals.
  
  
  METHODS
  The prosthesis consisted of two arrays with 50 to 74 electrodes. To test the feasibility of implanting the prosthesis and its efficacy, the prosthesis was implanted for 14 days into two rabbits. Optical coherence tomography (OCT) and ophthalmoscopy were performed 7 and 14 days after the implantation. Then the rabbits were euthanized, eyes were enucleated, and the posterior segment of the eye was examined histologically. In a second experiment, the arrays were implanted into two cats, and their ability to elicit neural responses was determined by electrically evoked potentials (EEPs) at the chiasm and by optical imaging of the retina.
  
  
  RESULTS
  All arrays were successfully implanted, and no major complications occurred during the surgery or during the 2-week postoperative period. Neither OCT nor ophthalmoscopy showed any major complications or instability of the arrays. Histological evaluations showed only mild cellular infiltration and overall good retinal preservation. Stimulation of the retina by the arrays evoked EEPs recorded from the chiasm. Retinal imaging showed that the electrical pulses from the arrays altered the retinal images indicating an activation of retinal neurons. The thresholds were as low as 100 μA for a chiasm response and 300 μA for the retinal imaging.
  
  
  CONCLUSIONS
  Implantation of a newly-developed dual-array STS prosthesis for 2 weeks in rabbits was feasible surgically, and safe. The results of retinal imaging showed that the dual-array system was able to activate retinal neurons. We conclude that the dual-array design can be implanted without complication and is able to activate retinal neurons and optic nerve axons.
authors.affiliation: Department of Applied Visual Science, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.|Department of Ophthalmology, RWTH Aachen University, Aachen, Germany.
authors.forename: Tibor Karl
authors.initials: TK
authors.lastname: Lohmann
authors.affiliation: Department of Applied Visual Science, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kanda
authors.affiliation: Department of Applied Visual Science, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Morimoto
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Endo
authors.affiliation: Department of Integrative Physiology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Tomomitsu
authors.initials: T
authors.lastname: Miyoshi
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nishida
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Motohiro
authors.initials: M
authors.lastname: Kamei
authors.affiliation: Department of Ophthalmology, RWTH Aachen University, Aachen, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Walter
authors.affiliation: Department of Applied Visual Science, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan. fujikado@ophthal.med.osaka-u.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Fujikado
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D002415:Cats; D004599:Electric Stimulation Therapy; D004567:Electrodes, Implanted; D004596:Electroretinography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005240:Feasibility Studies; D005451:Fluorescein Angiography; D008422:Materials Testing; D008839:Microelectrodes; D019919:Prosthesis Implantation; D011817:Rabbits; D012160:Retina / Q000502:physiology / Q000601:surgery; D055351:Retinal Neurons / Q000502:physiology*; D041623:Tomography, Optical Coherence; D014793:Visual Cortex / Q000502:physiology; D057488:Visual Prosthesis
chemical_list: D001672:Biocompatible Materials
keywords: Dual array; Retinal implant; Retinal prosthesis; STS; Suprachoroidal–transretinal stimulation