Declines in visual function with age have recently been linked to decrements in functional mobility and an increased risk of falling in older adults. Despite this knowledge, we know very little about how older adults use visual input to negotiate challenging terrain, surfaces and pathways. Tripping over obstacles, curbs or steps accounts for a large proportion of falls in older adults, and may be linked to inadequate or aberrant visual input. The purpose of this study is to examine the age-related differences in visual gaze patterns and visual input requirements as young and older adults negotiate obstacles, steps and stairs. Eye-tracking technology will be used to monitor precise gaze location with respect to the environmental scene as the subject ambulates over varied terrain. Liquid crystal display glasses will be used to selectively control the visual input subjects receive during key phases of each locomotor task while simultaneously measuring the biomechanics of task performance. Due to the cumulative effects of minor decrements in numerous physiologic systems, it is hypothesized that older adults will be more dependent upon visual input than young adults in order to maintain their balance during locomotor activities of daily living. It is anticipated that this work will provide insight into visually guided locomotion in healthy older adults, and provide the foundation for future work aimed at examining the visual strategies used during locomotion in older adults with low vision, coginitive impairment or other sensory loss. Results from this work could have implications for environmental modifications, visual rehabilitation training strategies, assistive device design and clinical relevance to fall prevention in the elderly. Understanding the differences between when and where older adults choose to look at key objects in their environment and when and where they need to look in order to safely navigate obstacles, steps and stairs will provide us with the foundation create new training programs and better environmental design to reduce the risk of falls. [unreadable] [unreadable] [unreadable]