title: The Argus II prosthesis facilitates reaching and grasping tasks: a case series.
abstract: BACKGROUND
  To evaluate the reach-to-grasp performance of patients fitted with an epiretinal artifical retina device.
  
  
  METHODS
  This was a hospital-based case series consisting of six patients fitted with the Argus II (Second Sight Medical Products Inc, California, USA) retinal prosthesis. Participants were asked to reach out and pick up a high-contrast cuboid object with the prosthesis in the 'On', 'Off' or 'Scrambled' setting presented in a randomised order. The 'Scrambled' setting consisted of a random, scattered signal presented to the prosthesis. The session was repeated after a 4-6 week period. Hand movements were measured using motion detection cameras. The number of successful object grasps was calculated.
  
  
  RESULTS
  The number of successful grasps was greater with the prosthesis in the 'On' setting (visit 1: median [interquartile range] percentage success: 'Off' = 0 [0 to 50]%, 'On' = 69 [67 to 95]%, 'Scrambled' = 59 [42 to 95]%; Friedman Chi-squared test statistic 6.5, p = 0.04; visit 2 median [IQR] percentage success: 'Off' = 0 [0 to 25]%, 'On' = 69 [53 to 100]%, 'Scrambled' = 28 [13 to 63]%; Friedman Chi-squared test statistic 8.4, p= 0.02).
  
  
  CONCLUSIONS
  The use of an electronic retinal prosthesis facilitates reach-and-grasp performance. Further work should explore how performance can be improved with targeted rehabilitation.
authors.affiliation: NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK. aachal.kotecha@ucl.ac.uk.
authors.forename: Aachal
authors.initials: A
authors.lastname: Kotecha
authors.forename: Joe
authors.initials: J
authors.lastname: Zhong
authors.forename: David
authors.initials: D
authors.lastname: Stewart
authors.forename: Lyndon
authors.initials: L
authors.lastname: da Cruz
mesh_terms: D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*; D011474:Prosthesis Design; D019919:Prosthesis Implantation; D012174:Retinitis Pigmentosa / Q000503:physiopathology / Q000601:surgery*; D012684:Sensory Thresholds; D014792:Visual Acuity; D057488:Visual Prosthesis