Visual prostheses are designed to restore partial functional vision in patients with total vision loss. Retinal visual prostheses provide limited capabilities as a result of low resolution, limited field of view and poor dynamic range. Understanding the influence of these parameters in the perception results can guide prostheses research and design. In this work, we evaluate the influence of field of view with respect to spatial resolution in visual prostheses, measuring the accuracy and response time in a search and recognition task. Twenty-four normally sighted participants were asked to find and recognize usual objects, such as furniture and home appliance in indoor room scenes. For the experiment, we use a new simulated prosthetic vision system that allows simple and effective experimentation. Our system uses a virtual-reality environment based on panoramic scenes. The simulator employs a head-mounted display which allows users to feel immersed in the scene by perceiving the entire scene all around. Our experiments use public image datasets and a commercial head-mounted display. We have also released the virtual-reality software for replicating and extending the experimentation. Results show that the accuracy and response time decrease when the field of view is increased. Furthermore, performance appears to be correlated with the angular resolution, but showing a diminishing return even with a resolution of less than 2.3 phosphenes per degree. Our results seem to indicate that, for the design of retinal prostheses, it is better to concentrate the phosphenes in a small area, to maximize the angular resolution, even if that implies sacrificing field of view.

翻译：视觉假体旨在为完全丧失视力的患者恢复部分功能性视觉。视网膜视觉假体由于分辨率低、视野有限及动态范围不足，其功能受到限制。理解这些参数对感知结果的影响能够指导假体的研究与设计。本研究评估了视觉假体中视野相对于空间分辨率的影响，通过搜索与识别任务测量了准确率与响应时间。24名视力正常的参与者被要求在室内场景中寻找并识别常见物体（如家具和家用电器）。实验中，我们采用了一种新型的模拟假体视觉系统，该系统支持简单高效的实验操作。我们的系统基于全景场景构建了虚拟现实环境，通过头戴式显示器使用户能够沉浸于场景中，感知周围全景。实验使用了公开图像数据集和商用头戴式显示器。我们同时开源了虚拟现实软件，以便复现和扩展实验。结果表明，当视野增大时，准确率下降且响应时间延长。此外，性能表现与角分辨率呈相关性，但即使分辨率低于每度2.3个光幻视点，其收益也呈现递减趋势。我们的结果似乎表明，在视网膜假体设计中，即使牺牲视野范围，将光幻视点集中在小区域内以最大化角分辨率是更优的设计策略。