The project is designed to help Dr. Bowers, an Optometrist with a PhD in vision rehabilitation research, make the transition to independent investigator. Her long-term career goal is to set up a vision rehabilitation laboratory that will utilize basic vision research approaches (such as visual search) to understand the limits imposed by vision impairment on activities of daily living (reading, walking and driving), leading to improved rehabilitation methods enabling visually impaired patients to lead more independent lives. Her immediate goals are to evaluate the impact of central field loss (CFL) on laboratory-based tests of visual search and multiple object tracking (MOT), and to relate this to functional performance on realistic tests of driving behaviors assessed using novel tests within the safe environment of a driving simulator. CFL is the presence of scotomas (blind areas) within the central visual field. The main cause of CFL is age-related macular degeneration, and its incidence is increasing with the aging of the general population. Many people with CFL continue to drive for social and economic reasons even though they do not meet the minimum visual acuity - (VA) required for driver licensing. Surprisingly, CFL is treated as if it were a simple VA loss when determining who can legally drive, possibly because little is known about the effects of central scotomas on the deployment of attention, a crucial visual process while driving. Studies will address the hypothesis that CFL impairs search and divided attention to a greater extent than a simple VA loss, resulting in failures of attention that may lead to impaired detection of potential hazards when driving. Tests of visual search and MOT will be developed during the mentored phase under the guidance of Dr. Wolfe, at his Visual Attention laboratory in Cambridge MA. Measurements of the CFL characteristics (scotoma and fixation) will be performed at the Schepens Eye Research Institute, Boston, MA. Simulator-based tests of pedestrian detection and vehicle-following will be developed under the guidance of Dr. Peli. In the independent phase, studies will be conducted to evaluate the impact of CFL on visual search and MOT, and to determine whether performance on these laboratory tests is related to performance in the simulator at the Boston, MA, Veterans Administration Medical Center. Performance of younger and older CFL subjects will be compared to that of age-matched normally-sighted subjects. This research will provide empirical data on the impact of CFL on skills relevant to driving safety and will identify clinical vision measures and visual search tests likely to be useful in screening CFL patients when determining fitness to drive.
. This research tackles a problem of major public health impact, determining which older people with impaired central vision can drive safely. This knowledge will provide a critical evidence base to inform policy makers when setting regulations for driver licensing. The findings have direct effects on the safety and quality of life of the growing number of older visually impaired people who want to maintain indepen- dence by continuing to drive, and indirect effects on the driving and pedestrian public who could be at risk.
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