MICCAI 2022 Daily – Monday

There are already prostheses that use this pathway, but little research has gone into optimizing the placement of electrodes on the prosthesis . That is where this work comes in, proposing a better way to arrange electrodes on the implant to produce greater phosphene coverage. “ Current devices arrange their electrodes on a rectangular grid because it’s compact and easy to fabricate, ” Michael tells us. “ Some people have looked at where to place the whole implant on the retina. Ashley was the first to ask, what if we moved every individual electrode around based on what we know about how these electrodes produce artificial vision? ” However, moving every electrode presents the problem of combinatorial explosion. Even in current devices with only 60 electrodes, there are many possibilities for arranging them. It is not usually technically feasible to find a solution. “ Ashley approached this as a greedy optimization problem , where one electrode is placed after another, ” Michael explains. “ We used a computational model of bionic vision to help predict what the vision would look like for a given electrode placement. By iterating over that, Ashley found a mathematically proven optimal solution. ” Greedy optimization is just that – a greedy approach to optimization. Each electrode is taken one at a time, its best placement is found, and it stays there. Then the same is done with the second electrode, taking a greedy approach to placing the electrodes in their optimal positions on the implant. 17 DAILY MICCAI Monday Ashley Bruce