Object localization, discrimination, and grasping with the optic nerve visual prosthesis.
OBJECTIVE
This study involved a volunteer completely blind from retinis pigmentosa who had previously been implanted with an optic nerve visual prosthesis. The aim of this two-year study was to train the volunteer to localize a given object in nine different positions, to discriminate the object within a choice of six, and then to grasp it.


METHODS
In a closed-loop protocol including a head worn video camera, the nerve was stimulated whenever a part of the processed image of the object being scrutinized matched the center of an elicitable phosphene. The accessible visual field included 109 phosphenes in a 14 degrees x 41 degrees area.


RESULTS
Results showed that training was required to succeed in the localization and discrimination tasks, but practically no training was required for grasping the object. The volunteer was able to successfully complete all tasks after training. The volunteer systematically performed several left-right and bottom-up scanning movements during the discrimination task. Discrimination strategies included stimulation phases and no-stimulation phases of roughly similar duration.


CONCLUSIONS
This study provides a step towards the practical use of the optic nerve visual prosthesis in current daily life.
Duret
Florence
F
Neural Rehabilitation Engineering Laboratory, Université catholique de Louvain, Brussels, Belgium.
Brelén
Måten E
ME
Lambert
Valerie
V
Gérard
Benoît
B
Delbeke
Jean
J
Veraart
Claude
C
D001766:Blindness / Q000534:rehabilitation / Q000601:surgery*; D004192:Discrimination, Psychological / Q000502:physiology* / Q000528:radiation effects; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D008875:Middle Aged; D009900:Optic Nerve / Q000503:physiopathology* / Q000528:radiation effects; D019736:Prostheses and Implants; D012189:Retrospective Studies; D013997:Time Factors; D014785:Vision, Ocular / Q000502:physiology* / Q000528:radiation effects; D014796:Visual Perception / Q000502:physiology / Q000528:radiation effects