Vision multiplexing: an engineering approach to vision rehabilitation device development.

Multiplexing is the transmission of two or more messages simultaneously over the same communication channel in a way that enables them to be separated and used at the receiving end. The normal visual system provides us with a very wide field of view at an apparent high resolution. The wide field of view is continuously monitored at a low resolution, providing information for navigation and detection of objects of interest. These objects of interest are sampled over time using the high-resolution fovea. Most disabling visual conditions impact only one of the components, the peripheral low-resolution wide field or the central high-resolution fovea. The loss of one of these components prevents the interplay of central and peripheral vision needed for normal function and causes disability. Traditionally low-vision aids replace or supplement the missing function, but usually at a cost of a significant loss in the surviving function. For example, magnifying devices increase resolution but reduce the field of view, whereas minifying devices increase the field of view but reduce resolution. A proposal to resolve many of the problems of current visual aids by exploring a general engineering approach--vision multiplexing--that takes advantage of the dynamic nature of human vision is presented. Vision multiplexing seeks to provide both the wide field of view and the high-resolution information in ways that could be accessed and interpreted by the visual system. This paper describes the use of optical methods and computer technologies in the development of a number of new visual aids, all of which apply vision multiplexing to restore the interplay of central and peripheral vision using eye movements in a natural way.