Visual performance using a retinal prosthesis in three subjects with retinitis pigmentosa

Am J Ophthalmol. 2007 May;143(5):820-827. doi: 10.1016/j.ajo.2007.01.027. Epub 2007 Mar 23.


Purpose: To assess visual task performance in three blind subjects implanted with epiretinal prostheses.

Design: Prospective, investigational device exemption trial.

Methods: Three subjects with light perception or no light perception vision were enrolled at a single center. All subjects had retinitis pigmentosa (RP). Main inclusion criteria: light perception or worse vision in one eye and some visual experience as an adult before blindness. Main exclusion criteria included other ophthalmic problems. A prototype retinal prosthesis was implanted in the eye with worse light sensitivity. The prosthesis had 4 x 4 array of platinum electrodes tacked to the epiretinal surface. The prosthesis was wirelessly controlled by a computer or by a head-worn video camera. Visual function testing was performed in single masked or double masked fashion. Scores from the visual task were compared to chance to determine statistical significance.

Results: The subjects performed significantly better than chance in 83% of the tests. Using the video camera, subjects scored as follows on simple visual tasks: locate and count objects (77% to 100%), differentiate three objects (63% to 73%), determine the orientation of a capital L (50% to 77%), and differentiate four directions of a moving object (40% to 90%). A subset of tests compared camera settings using multipixels vs single pixels. Using multipixel settings, subjects performed better (17%) or equivalent (83%) in accuracy and better (25%) or equivalent (75%) in reaction time.

Conclusions: Three RP implant subjects used epiretinal prostheses to perform simple visual tasks. Multipixel settings proved slightly more effective than single pixel settings.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Electrodes, Implanted*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Prospective Studies
  • Prostheses and Implants*
  • Prosthesis Implantation
  • Retina / physiology*
  • Retinitis Pigmentosa / physiopathology*
  • Retinitis Pigmentosa / surgery*
  • Signal Processing, Computer-Assisted*
  • Task Performance and Analysis
  • Video Recording
  • Vision Disorders / physiopathology
  • Vision Disorders / surgery
  • Visual Perception / physiology*