S E Hassan¹, D R Geruschat¹, K A Turano²
¹Maryland School for the Blind/ Johns Hopkins Wilmer Eye Institute, Lions Vision Research Center, Baltimore, United States; ²Johns Hopkins Wilmer Eye Institute, Lions VIsion Research Center, Baltimore, United States
Background. The act of crossing a street involves a series of tasks such as information gathering, decision making and good mobility skills. Despite the importance of street crossing to daily life, few studies have evaluated the gaze behavior of people whilst crossing the street. The purpose of this study was to categorize the objects that people with normal vision and with two types of vision loss look at when crossing a street.
Methods. Using a portable eye tracker, direction of gaze was measured in two people with age-related macular degeneration (ARMD), two people with glaucoma and in three people with normal vision of similar age as they stood and crossed a busy inter-section at a roundabout. Objects in the environment that subjects looked at were classified into one of four groups; (i) cars, (ii) roadway (the intersection and surrounding streets), (iii) general environment (trees, billboards and buildings), and (iv) crossing elements (curbs, cross walk lines and sidewalk).
Results. The normally sighted subjects directed approximately one third of their fixations on crossing elements, whilst subjects with ARMD and glaucoma made over half of their fixations on crossing elements. All subjects directed less than 25% of their fixations on cars, and less than 10% on the roadway.
Conclusions. When crossing a busy inter-section, people with ARMD and glaucoma visually survey the environment and direct their gaze onto different objects compared to normally sighted people of similar age.
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