Influence of field of view in visual prostheses design: Analysis with a VR system

Abstract

Objective. 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. Approach. 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. Main results. 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. Significance. 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.

Immersive Virtual Reality Simulations of Bionic Vision

“…Stimuli for these low-level visual function tests were often presented on monitors [30,49] or in HMDs [9,52]. Some studies also tested the influence of FOV [41,45] and eye gaze compensation [46] on acuity. Others focused on slightly more complex tasks such as letter [56], word [38], face [11,14], and object recognition [33,50,55].…”

“…In summary, previous SPV research has assumed that the scoreboard model produces phosphenes that are perceptually similar to real bionic vision [48,56], and that findings from an HMD-based task would more accurately represent the experience of a bionic eye user than a monitor version [41,45,54]. In this paper we aim to systematically evaluate these assumptions with a within-subjects (repeated measures) design, allowing for direct comparisons in performance across different model parameters and display conditions.…”

Assessing visual acuity in visual prostheses through a virtual-reality system

“…The SPV system is a standard procedure for non-invasive evaluation using normal vision subjects. Generally, in SPV, a low-resolution image of the view is presented on a computer screen [45] or on a head-mounted display [46][47][48] glasses to a normally sighted user (see Figure 2). It allows researchers to rigorously investigate the minimal requirements for a functional visual prosthesis and to explore which variables are important in the development of a visual prosthesis.…”

“…Some researchers have used the combination of SPV with a VR system for experimentation. Sanchez et al [46] analyzed the influence of field of view with respect to resolution in visual prostheses through a study with a SPV setup using a VR system. Kasowski et al [53] proposed to embed biologically realistic models of SPV in immersive VR so that sighted subjects can act as virtual patients in real-world tasks.…”

Augmented reality navigation system for visual prosthesis

“…In a posterior study, Dagnelie et al [26] explored minimal visual resolution requirements of a simulated retinal electrode array for mobility in real and virtual environments, experienced by normally sighted subjects in video headsets. Sanchez-García et al [27] evaluated the influence of field of view with respect to spatial resolution in visual prostheses using a virtual-reality system for more realistic SPV environments using panoramic scenes. However, they mainly focused on reading and object recognition.…”