Functional outcome in subretinal electronic implants depends on foveal eccentricity

Invest Ophthalmol Vis Sci. 2013 Nov 19;54(12):7658-65. doi: 10.1167/iovs.13-12835.


Purpose: An active microelectronic subretinal implant, developed to replace the photoreceptive function in hereditary degenerations of the outer retina, has been applied in a pilot and clinical study in patients with end-stage retinal degeneration.

Methods: The study population comprised 20 blind patients, all of whom lost vision as result of a hereditary retinal disease. An active visual implant was placed surgically within the subretinal space of each patient: subfoveal placement in eight patients (group 1) and parafoveal placement in 12 (group 2). Standardized low-vision tests, including light perception, light localization, movement detection, grating acuity, and visual acuity by Landolt C-rings, were used under masked, randomized implant-OFF and implant-ON conditions. For the chip-mediated vision functional results of both subject groups were compared.

Results: Three of 20 patients were excluded from analysis because of surgical or technical implant issues. Among patients with nonfoveal placement of the implant, 80% could perceive light, 10% recognized location, and 10% correctly distinguished stripe patterns up to a resolution of 0.33 cycles/degree. No nonfoveal placement patient passed the motion or Landolt C-ring tests. When the implant was placed subfoveally, 100% of patients could perceive light and determine light localization, 75% could resolve motion up to 35°/s, 88% correctly distinguished stripe patterns up to a resolution of 3.3 cycles/degree, and 38% passed a Landolt C-ring test with a decimal visual acuity of up to 20/546 (logMAR 1.43).

Conclusions: Subfoveal placement of active subretinal visual implants allows superior measurable outcomes compared to para- or nonfoveal placement locations. ( numbers, NCT01024803, NCT00515814.).

Keywords: artificial vision; neuroprosthetics; retinitis pigmentosa; subretinal visual implant.

Publication types

  • Clinical Trial, Phase I
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blindness / rehabilitation
  • Electrodes, Implanted*
  • Female
  • Fovea Centralis / physiopathology*
  • Fovea Centralis / surgery
  • Humans
  • Male
  • Middle Aged
  • Motion Perception / physiology
  • Pilot Projects
  • Retinal Degeneration / physiopathology*
  • Retinal Degeneration / surgery*
  • Treatment Outcome
  • Vision Tests
  • Visual Acuity / physiology
  • Visual Perception / physiology
  • Visual Prosthesis*

Associated data