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Essam Saad Almutleb, Arthur Bradley, Jason Jedlicka, Shirin E Hassan; Street-Crossing Decision-Making in Pedestrians with Simulated Central Field Loss. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3285. doi: https://doi.org/.
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Street-crossing decision-making is negatively affected by vision loss. This study tested the hypothesis that as the size of an experimentally induced central scotoma increases, street-crossing performance worsens
Street-crossing decisions were measured in twelve young subjects aged between 23 and 31 years while monocularly viewing a non-signalized one way street for different vehicular arrival times (0.3-17 sec). Using a 5-point rating scale, subjects judged whether they could cross the street prior to vehicular arrival with habitual vision and simulated central field loss (CFL) using contact lenses (CLs) with different central opaque diameters. Using Receiver Operating Characteristics (ROC) curve analysis, we obtained subjects’ accuracy (amount of time in seconds where subjects either over- or under-estimated vehicular arrival time relative to their actual crossing time) and reliability (how quickly subjects transitioned from judging insufficient to adequate time to cross relative to their actual crossing time). Underestimation of vehicular arrival time relative to subjects’ crossing time generated positive inaccuracies but safe crossing judgments the converse was true for negative values. The quicker the transition from judging insufficient to adequate time to cross, the more reliable and hence better performance. The converse was true for slow transitions
The centrally opaque CLs induced central scotomas with mean diameter of 18.85 degrees (±7.37 degrees). The mean accuracy values in street-crossing decisions for normally-sighted people with and without a simulated central scotoma were 1.43±0.27 sec and 1.40±0.47 sec, respectively. No significant difference in accuracy was found between both conditions (p= 0.780). The median of reliability in street-crossing decisions was 0.55 for both conditions. Surprisingly, no statistically significant correlation was detected between scotoma size and accuracy and reliability in subjects’ street-crossing decisions. (p=0.567 and p=0.265, respectively)
This data suggests that normally-sighted people with and without a simulated CFL adopted a safe street-crossing strategy by underestimating the vehicular arrival times relative to their crossing time. Moreover, an induced central scotoma did not appear to negatively affect the accuracy and reliability of subjects’ street-crossing decisions
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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