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Blind subjects implanted with the Argus II retinal prosthesis are able to improve performance in a spatial-motor task
  1. A K Ahuja1,
  2. J D Dorn1,
  3. A Caspi1,
  4. M J McMahon1,
  5. G Dagnelie2,
  6. L daCruz3,
  7. P Stanga4,
  8. M S Humayun5,
  9. R J Greenberg1,
  10. Argus II Study Group
  1. 1Second Sight Medical Products, Sylmar, California, USA
  2. 2Lions Vision Research and Rehab Center, Baltimore, Maryland, USA
  3. 3Moorfields Eye Hospital, London, UK
  4. 4Manchester Royal Eye Hospital, Manchester, UK
  5. 5Dohey Eye Institute, Keck School of Medicine, Los Angeles, California, USA
  1. Correspondence to Dr Ashish K Ahuja, Sight Medical Products, bldg. 3, 12744 San Fernando Blvd., Sylmar, CA 91342, USA; aahuja{at}


Background/aims To determine to what extent subjects implanted with the Argus II retinal prosthesis can improve performance compared with residual native vision in a spatial-motor task.

Methods High-contrast square stimuli (5.85 cm sides) were displayed in random locations on a 19″ (48.3 cm) touch screen monitor located 12″ (30.5 cm) in front of the subject. Subjects were instructed to locate and touch the square centre with the system on and then off (40 trials each). The coordinates of the square centre and location touched were recorded.

Results Ninety-six percent (26/27) of subjects showed a significant improvement in accuracy and 93% (25/27) show a significant improvement in repeatability with the system on compared with off (p<0.05, Student t test). A group of five subjects that had both accuracy and repeatability values <250 pixels (7.4 cm) with the system off (ie, using only their residual vision) was significantly more accurate and repeatable than the remainder of the cohort (p<0.01). Of this group, four subjects showed a significant improvement in both accuracy and repeatability with the system on.

Conclusion In a study on the largest cohort of visual prosthesis recipients to date, we found that artificial vision augments information from existing vision in a spatial-motor task.

Clinical trials registry no NCT00407602.

  • Retinal prosthesis
  • retinitis pigmentosa
  • low vision
  • retinal degeneration
  • retina
  • degeneration
  • clinical trial
  • low vision aid
  • prosthesis

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  • Funding National Institutes of Health (Bethesda, MD, USA) grant no. 5R01EY12893.

  • Competing interests AKA, JDD, AC, MJMcM and RJG are employees of and have a financial interest in Second Sight Medical Products. GD, LdaC and PS belong to institutions that receive funding from Second Sight Medical Products to support the study. The individuals themselves have no financial interest in Second Sight Medical Products.

  • Patient consent Obtained.

  • Ethics approval This study was conducted with ethics approval from all participating clinical sites: Doheny Eye Institute at the University of Southern California (Los Angeles, California, USA); Retina Foundation of the Southwest (Dallas, Texas, USA); Moorfields Eye Hospital (London, UK); the University of California at San Francisco (San Francisco, California, USA); Wilmer Eye Institute at the Johns Hopkins School of Medicine (Baltimore, Maryland, USA); Wills Eye Institute at the University of Pennsylvania and the Scheie Eye Institute (Philadelphia, Pennsylvania, USA), The Edward S. Harkness Eye Institute at Columbia University and Lighthouse International (New York, USA); Puerta de Hierro Centro Medico (Guadalajara, Mexico); Centre Hospitalier National de Ophtalmologie des Quinze-Vingts (Paris, France); Hôpitaux Universitaires de Genève (Geneva, Switzerland).

  • Provenance and peer review Not commissioned; externally peer reviewed.