Virtual reality simulation of epiretinal stimulation highlights the relevance of the visual angle in prosthetic vision

Objective. Retinal prostheses hold the potential to restore artificial vision in blind patients suffering from outer retinal dystrophies. The optimal number, density and coverage of the electrodes that a retinal prosthesis should have to provide adequate artificial vision in daily activities is still an open question and an important design parameter needed to develop better implants. Approach. To address this question, we investigated the interaction between the visual angle, the pixel number and the pixel density without being limited by a small electrode count. We implemented prosthetic vision in a virtual reality environment in order to simulate the real-life experience of using a retinal prosthesis. We designed four different tasks simulating: object recognition, word reading, perception of a descending step and crossing a street. Main results. The results of our study showed that in all the tasks the visual angle played the most significant role in improving the performance of the participant. Significance. The design of new retinal prostheses should take into account the relevance of the restored visual angle to provide a helpful and valuable visual aid to profoundly or totally blind patients.