D. Ghezzi1, M.J.I. Airaghi Leccardi1, N.A.L. Chenais1, P. Vagni1, C.H. Vila1, E.G. Zollinger1, T.J. Wolfensberger2
1 Medtronic Chair in Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École polytechnique fédérale de Lausanne, Switzerland
2 Department of Ophthalmology, University of Lausanne, Hôpital Ophtalmique Jules-Gonin, Fondation Asile des Aveugles, Lausanne, Switzerland.
Purpose: To validate ex-vivo and in-vivo a wide-field and high-density epiretinal prosthesis.
Methods: POLYRETINA is a wide-field high-density epiretinal prosthesis which contains 10,498 photovoltaic pixels (80-µm diameter, 120-µm pitch) distributed with a density of 80.33 pixels mm-2 over an active area of 12.9 mm in diameter. The prosthesis covers a visual angle of 46.3 degrees, once bonded to its curved flexible support. We investigated ex-vivo with retinal explants from retinal degeneration 10 mice the response resolution provided by this high-density retinal prosthesis. Also, we investigated in-vivo in blind Göttingen minipigs the restoration of visual responses to light flashes mediated by the POLYRETINA prosthesis.
Results: The results showed that (i) the 10,498 photovoltaic pixels are physically and functionally independent and (ii) the coating with titanium nitride reduced the mechanical stress of the pixels and increased their photovoltaic performance, thus opening up the possibility of high-resolution single-pixel stimulation of RGCs. Experiment ex-vivo showed that the wide-field and high-density organic photovoltaic epiretinal prosthesis allows for single-pixel stimulation of RGCs at safe irradiance levels. Also, a single retinal ganglion cell receptive field is activated only by one or two photovoltaic pixels, to confirm the high-resolution of network-mediated epiretinal stimulation. Last, the high-resolution in stimulation allows for targeting sub-portions of the same receptive field of a RGC. Preliminary experiments in-vivo showed that POLYRETINA restored flash evoked light responses in blind Göttingen minipigs at safe irradiance levels.
Conclusions: These results demonstrated that an epiretinal prosthesis could achieve a high spatial resolution in retinal stimulation, together with a wide visual angle. Preliminary data in blind Göttingen minipigs showed the translational potential of POLYRETINA. I will present the recent results and discuss the outlook and challenges for future developments.
Financial disclosure: None