D R Geruschat¹, S E Hassan¹, 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: Mobility instructors assume that crossing a street safely requires more attention (mental effort) than walking on a sidewalk. The purpose of this study was to test this assumption.
Method: We evaluated the amount of mental effort required to cross 3 types of streets: (1) quiet residential, (2) light controlled intersection in a small business district, and (3) a busy roundabout. Partially sighted and fully sighted subjects participated in the study. Visual pathology and extent were varied. Pathologies included albinism, retinitis pigmentosa (RP), homonymous hemianopsia, glaucoma, age-related maculopathy (AMD), and retinopathy of prematurity (ROP). Mental effort was measured as response time to an auditory tone. The subject wore a backpack containing a lightweight computer that generated the tone and recorded the response time. The subject wore earphones and carried a small joystick in their hand that they "clicked" each time they heard the tone. This provided a measure of reaction time.
Results: The results demonstrate that partially sighted subjects and fully sighted subjects have equivalent reaction times while walking a simple course. There was a significant difference in reaction time when crossing the street, with the low vision subjects having significantly slower reaction times when compared with the fully sighted.
Conclusion: The findings demonstrate that more mental effort is required for crossing the street for subjects with low vision.
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