According to The National Advisory Eye Council, a program goal is to """"""""Develop assistive devices ... and rehabilitation strategies to minimize the impact of visual impairment in everyday life, and reduce disability and societal limitations among visually impaired persons"""""""" (Vision Research-A National Plan: 1999-2003, National Eye Institute). In accordance with this guideline, the proposed pilot study will measure and attempt to correct the reading disability of patients who retain only a small central island of vision due to advanced retinal degeneration or glaucoma, or only the left or right visual field due to stroke. These patients, who number in the thousands in the United States, are handicapped for reading standard, stationary text because they lack adequate parafoveal visual cues for smoothly shifting fixation from word to word and from line to line, and because some have reduced visual acuity as well. We plan to evaluate 150 patients with different forms of retinal degeneration or glaucoma and 30 patients with stroke. This program will quantify their reading speeds to standard, stationary text and relate reading speed to conventional measures of vision to develop a quantitative clinical frame of reference for their reading disability. We will explore whether their reading speeds to stationary text can be improved by tailoring the letter spacing, letter size, page width, and contrast polarity to their disease type and stage. Testing will also involve measuring their reading speed to text presented serially to the same location of the visual field, a format that minimizes the need for eye movements, and that should, therefore, little depend upon the absence of parafoveal cues; this format has been reported to result in up to four-fold faster reading by normal subjects. Since software is available for presenting text serially to the same location, either on-line or off-line, and since palmheld wireless devices are commercially available, a serial mode of presentation could be a practical, mobile solution for patients with these types of visual field loss.
