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Laura Cinelli, stanislao rizzo; Correlation analysis between Argus II Retinal Prosthesis Patients performances and electrophysiological data.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4682.
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© ARVO (1962-2015); The Authors (2016-present)
The Argus II Retinal Prosthesis System (Argus II) is currently the first and only retinal prosthesis with both FDA (2013) and CE (2011) approval and has been implanted in more than 210 severely vision impaired patients. Since 2011 we implanted 29 patients with the Argus II in our centers. We followed up closely patients’ progresses using three visual function tests designed to measure their ability to localize objects, discriminate motion, and discriminate gratings’ orientation.Noticing that the population performed statistically better with the system on versus off in these tasks, but that the results varied from patient to patient, we wanted to verify if electrophysiological factors are affecting the performances in these subjects, therefore an analysis of the retinal health and implant position could predict or correlate with patients performances.We chose electrode-retina distance (known factor in determining the amount of current necessary to induce a visual percept), retina thickness (associated with the extent of retinal degeneration in advanced stages of RP), and electrical thresholds.
Starting from OCT images obtained by Heidelberg Engineering or Nidek systems, we measured the electrode-retina distance, retinal thickness and electrodes-fovea distances of 19 Argus II patients.Electric threshold measurements and visual acuity tests were done by the custom developed Argus II software.Correlation analysis between the parameters has been performed in Matlab and Excel.
We performed correlation analysis between patients’ performances and electrophysiological and geometric data. We found no correlation between retinal thickness and ability to localize objects or discriminate movements. We observed a slight correlation between the mean distance between implant and retina and both the visual function tests. Average threshold values correlate only with the ability of movement detection.
Our results show that electrode–retina distance and thresholds values affect performances. We conclude that a tight juxtaposition of the array to the retina is critical for optimizing the benefit of the patients.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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