Penelope Allen1,2, Christopher Williams3, David Nayagam3, Chi Luu4, Nicholas Barnes5, Maria Kolic4, Carla Abbott4, Kiera Young4, Robert Briggs1,3, William Kentler6, Samuel Titchener3, Jonathan Yeoh1,4, Matthew Petoe3
Purpose: The success of our prototype clinical trial of a suprachoroidal retinal prosthesis lead us to develop a 44 channel fully implantable device, with the aim of providing visual information to pro- foundly visually impaired patients, allowing them to utilize this device at home.
Methods: Two of four planned patients (P1 and P2) with end-stage rod – cone dystrophy (retinitis pig- mentosa) and perception of light visual acuity were implanted with a 44 channel electrode array in the suprachoroidal space at the Royal Victorian Eye and Ear Hospital during 2018. After recovery they com- menced stimulation of the device in the psychophys- ics laboratory.
Post operative follow-up included clinical examina- tion, fundus photography and optical coherence tomography (OCT) to assess surgical recovery and impact of the surgery on the eye.
Results: The surgical procedures took 260 and 204 minutes and were uncomplicated. At the comple- tion of surgery, impedance testing showed in P1 and P2 all electrodes were functional. Post operative recovery was uneventful. Fundus imaging and OCT imaging conﬁrmed the position of the devices and the absence of retinal trauma. Psychophysical testing produced a phos- phene map and lab based testing in preparation for ori- entation and mobility training commenced.
Conclusions: A 44 channel retinal prosthesis can be safely implanted in the suprachoroidal space. Over four months of post operative follow-up clinical ﬁndings, fundus photography and OCT imaging conﬁrm device stability. It was possible to produce a phosphene map for both patients and commence lab-based training in preparation for orientation and mobility activities.