Article
Measurement of visual cortex activity with near infrared spectroscopy after endoscope assisted ARGUS II epiretinal prosthesis implantation in retinitis pigmentosa patients
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Published: | November 30, 2017 |
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Objective: To assess the visual cortex activity changes using near-infrared spectroscopy (NIRS), which is a non-invasive and ready method compare to functional magnetic resonans imaging (fMRI), after Argus II implantation surgery.
Method: In order to decrease the incidence of pars plana sclerotomy incision-related complications, inadequate placement of the electrode array over the fovea, Argus II epiretinal prosthesis implantation in 3 retinitis pigmentosa (RP) patients were done under endoscopic control. We used the near-infrared spectroscopy (f-NIRS) device (ETG-4000; Hitachi Medical, Japan) to measure cortical activity during the visual cortex stimulation, 2 and 6 months later after the surgery. Four different paradigms were used (Static checkerboard, On-off checkerboard, Alternating checkerboard, Moving ball). Visual cortex activity was recorded in two conditions; namely the bionic eye-on condition and the bionic eye off- condition. All paradigms were presented in four blocks. The mean activity represents the grand average of these blocks.
Results: We did not observe activity difference in the checker board conditions. However there was a marked activity difference in the moving ball paradigm between the bionic eye-on and off conditions.
Discussion: The NIRS instrument measures relative changes in oxygenated and deoxygenated haemoglobin through optodes (emitters and detectors) of 2 wavelengths (695 and 830 nm). NIRS method can be used in implanted RP patients to assess the visual cortex activity easily instead of fMRI.
Acknowledgement: This work was supported by Second Sight Inc.