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Alexandra R. Bowers, Concetta F. Alberti, P. Matthew Bronstad, Amanda Albu, Todd Horowitz; Does Dynamic Attention Predict Hazard Detection In People With Central Field Loss?. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3150. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The ability of visually impaired people to deploy attention effectively to maximize use of their residual vision in dynamic situations is fundamental to safe mobility (walking and driving). Clinical vision measures, however, typically involve only simple tests with static targets. We conducted a preliminary study to evaluate whether a laboratory-based test of dynamic attention (multiple object tracking; MOT) could predict the ability of people with central field loss (CFL) to detect moving hazards in a driving simulator.
11 people with bilateral CFL (VA 20/32 to 20/200) and 12 age-similar controls participated. Dynamic attention was evaluated with a brief computer-based MOT task. Participants tracked 3 of 6 high-contrast black disks, all moving randomly against a light gray background. Speed was adjusted on each trial using a simple staircase rule: speed was increased when all 3 targets were reported correctly, and decreased when any errors were made. The dependent variable was the speed threshold for 60% correct performance, obtained using Quest (Watson and Pelli, 1983). Hazard detection was evaluated in a driving simulator. Participants drove 5 pre-determined routes (each about 10 minutes) in urban and rural areas and pressed the horn whenever they detected pedestrians (n = 60) that walked or ran on a collision course toward their car. The dependent variable was the proportion of untimely detections (including detection failures and reaction times too long to avoid a potential collision).
MOT thresholds of CFL participants were significantly lower (worse) than those of controls (6.5 deg/sec ± 3.6 and 11.6 deg/sec ± 4.1; p = 0.01), and were not correlated with traditional clinical vision measures (acuity, contrast sensitivity, scotoma size). The proportion of untimely detections was higher for CFL participants than controls (16% and 2%; p = 0.001) and was significantly correlated with MOT scores; CFL participants with worse MOT scores had worse hazard detection performance (r = -0.68; p = 0.02).
These preliminary results suggest that a dynamic attention test may provide a useful measure of functional visual ability relevant to visual performance in real-world tasks.
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