title: Retinal prostheses for the blind.
abstract: BACKGROUND
  Using artificial means to treat extreme vision impairment has come closer to reality during the past few decades. The goal of this research has been to create an implantable medical device that provides useful vision for those patients who are left with no alternatives. Analogous to the cochlear implants for some forms of hearing loss, these devices could restore useful vision by converting visual information into patterns of electrical stimulation that excite the remaining viable inner retinal neurons in patients with retinitis pigmentosa or age-related macular degeneration.
  
  
  METHODS
  Data for this review were selected through a comprehensive literature search.
  
  
  RESULTS
  Advances in microtechnology have facilitated the development of a variety of prostheses that can be implanted in the visual cortex, around the optic nerve, or in the eye. Some of these approaches have shown the promise of providing useful visual input to patients with visual impairments.
  
  
  CONCLUSIONS
  While the development of various retinal prostheses have shown promise in limited clinical trials, there are distinct advantages and disadvantages for each type of prosthesis. This review will focus primarily on the Epiretinal Intraocular Retinal Prosthesis, studied by our group, but will also briefly review other modalities: the subretinal prosthesis, cortical prosthesis, and optic nerve prosthesis.
authors.affiliation: Doheny Retina Institute, Doheny Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, 1450 San Pablo Street (Room 3600), Los Angeles, CA 90033, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Javaheri
authors.forename: David S
authors.initials: DS
authors.lastname: Hahn
authors.forename: Rohit R
authors.initials: RR
authors.lastname: Lakhanpal
authors.forename: James D
authors.initials: JD
authors.lastname: Weiland
authors.forename: Mark S
authors.initials: MS
authors.lastname: Humayun
mesh_terms: D004599:Electric Stimulation Therapy; D004567:Electrodes, Implanted; D006801:Humans; D008268:Macular Degeneration / Q000150:complications*; D019919:Prosthesis Implantation; D012174:Retinitis Pigmentosa / Q000150:complications*; D014786:Vision Disorders / Q000209:etiology / Q000534:rehabilitation*