The Virtual Retinal Display (VRD) developed by the PIs and their colleagues creates an image by scanning non-coherent or coherent light across the retina in a raster pattern, rather than using a conventional image plane screen. The VRD has full color and a broad luminance range for high contrast, even in bright ambient daylight; the mechanism will eventually be miniaturized to fit on a spectacle frame, making wearable displays feasible. Because of these attributes, and the fact that VRD parameters can be configured in various combinations to alter characteristics of the perceived image such as field of view, resolution and the size of the scanning aperture, the VRD holds great promise for enhancing vision in the partially sighted. The goal of this research is to investigate how best to realize this promise. The small exit pupil of the VRD allows clear images to be seen by users with corneal distortions and/or partial opacities of the lens such as cataracts. For central retinal diseases such as macular degeneration, the VRD can be configured to direct high contrast, large feature images to the peripheral retina. For peripheral disorders, where only a small central area may remain functional, the display can be configured with a high-resolution narrow field of view. Pilot tests of subjects with partial loss of vision indicate that even non-optimized images from the VRD can usually be seen better than CRT images. The PIs will conduct psychophysical visual testing with partially sighted users, and systematic comparison with standard computer displays (CRTs and LCDs), to determine for a variety of visual disorders the appropriate VRD scanning and modulation characteristics for optimal image resolution, contrast sensitivity, color perception and absence of flicker. The ability of users to view text, see video images and use common computer applications such as word processors, spreadsheets, and web browsers will also be assessed. The expectation is that this research will ultimately lead to new visual display products and techniques to enhance computer access for people with low vision, including the growing elderly population
