Abstract
Purpose: :
To provide an update on performance outcomes in the Argus II Retinal Prosthesis Study.
Methods: :
All subjects were implanted with a Second Sight Argus II implant and had bare light perception or worse due to retinitis pigmentosa (clinicaltrials.gov NCT00407602 ). Visual function was evaluated by grating visual acuity, assessing the ability to determine the direction of motion of a line and the location of a square on an LCD screen. Subjects’ ability to identify letters was also measured. Orientation and mobility (O&M) tests involved following a line and finding a door.
Results: :
32 subjects have been implanted at 11 centers and all use the system at home. As of December 1, 2009, subjects have been implanted an average of 16 ± 11 months (range of 4 - 38 mos.). In the O&M tests, subjects were able to successfully navigate to the door and to the end of the line more often with the System ON vs. OFF (average success rate across all follow-up time points (n=19 subjects) door: 58% [ON] vs. 32% [OFF]; line: 64% [ON] vs. 26% [OFF]). At most follow-up time points (up to 24 months), these differences were statistically significant. At the most recent follow-up visits, 92% of subjects (23/25) perform Square Localization tests statistically better with the System ON vs. OFF and 58% (14/24) perform Direction of Motion tests better with the System ON vs. OFF. 40% of subjects in the most recent Argus II cohort (6/15) have statistically measurable grating visual acuity better than 2.9 logMAR (Snellen 20/15900) with System ON in their implanted eye and the best subject measured 1.8 logMAR (20/1260). Subjects were able to correctly identify letters in a closed set 73% of the time with the System ON vs. 17% with the System OFF (n=22 subjects).
Conclusions: :
With up to 3.2 years follow-up on 32 subjects, this is the largest study of a visual prosthesis to date. The results confirm previous reports on the ability of the Argus prosthesis to provide visual function over the long-term.
Clinical Trial: :
www.clinicaltrials.gov NCT00407602
Keywords: retina • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • retinal degenerations: hereditary