G L Goodrich, J Kirby, B Donald, P Wagstaff, T Oros, L Jaffray, S Homesley
VA Palo Alto Health Care System, Western Blind Rehabilitation System, Palo Alto, CA , United States
A new type of low vision reading display has recently been introduced. Adapted from military heads-up displays, it uses a monochromatic (650 nm) red laser to "paint" an image on the user's retina. The effective display has 800 X 600 pixels resolution and a field of view equivalent to a 19-inch (48.3 cm) monitor at arms length. The head mounted unit weighs 1 pound (454 grams). The prototype, referred to as Nomad, has a brightness of between 1 and 800 foot lamberts. We compared reading performance for 20 subjects with the Nomad, the prescribed optical device, and a CCTV. Three additional subjects could not read with either an optical device or CCTV. Five training sessions with each device was provided for all subjects reading with the three different aids so that all subjects had equal familiarity with all devices. Subject's pathology, visual acuity, contrast sensitivity, duration of visual impairment, and age were recorded as were reading speeds and durations. The mean logMAR visual acuity was .1.125. Subjects read fastest with the CCTV and with about equal speed with the optical device and the Nomad. Reading durations were shortest with the optical device and about equal with the CCTV and Nomad. Thus, reading productivity (speed times duration) with the Nomad was intermediate between the optical device and CCTV. Subjects primarily appreciated the Nomad's brightness and clarity, although they also felt the prototype was uncomfortable. In particular the device may hold promise for low vision patients who can no longer read with conventional reading devices. Also, because several subjects reported improved visual awareness, the Nomad may have a role in low vision training. We will discuss our results and implications of this technology for future reading devices.
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