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I. Cunningham, P.C. Knox, F.J. Rowe, A.C. Fisher; Visual Field Assessment in conditions of Divided Attention using SITA. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):5466.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To assess the effect of dividing attention on visual field sensitivity using the SITA interactive algorithm running on a Humphrey Field Analyzer (HFA) combined with asynchronous tasks running at fixation. Methods: One eye of 14 young subjects (mean 20.4±1.7yrs; range 18–24) was assessed using the 30–2 SITA Standard program running on an HFA Series VII (model 740i) under three different conditions: field task alone (full attention; FA1); field task plus a second asynchronous detection task run at fixation (DA1); field task plus a discrimination task in which targets and distractors were presented at fixation (DA2). A small star or triangle (approximately 1° in height) was projected at fixation for 50ms. In DA1 subjects were instructed to respond to either a star or a triangle. For DA2 they were instructed to respond to only the triangle (target) and ignore stars (distractors). The HFA response button was held in the dominant hand, and the response button for the fixation task was held in the non–dominant hand. Results: Using ANOVA we found that both visual field region (x4) and condition (x3) had a significant effect on threshold (F3,167= 131, p<0.001; F2,167= 4, p<0.05). Test time for the standard threshold programme increased slightly in DA conditions (FA: 343±30sec; DA1: 371±32sec; DA2: 390±46sec; p=0.24). The mean reaction time for the central detection task increased significantly when combined with the visual field threshold programme (FA1: 359.41±59.37msec vs. DA1: 540.65 ±50.69msec vs. DA2: 606.82±64.11msec; F2,41=74.5; p<0.001). Fixation losses, false positives and false negative errors all increased slightly in DA conditions. Conclusion: We have shown previously that a detection task at fixation has no effect on visual fields in young subjects. Here the combination of discrimination and field tasks, did alter visual field sensitivity. We would predict a greater effect in older subjects. Visual fields measured in these divided attention conditions, particularly when a discrimination task is used at fixation, may provide a better estimate of vision available for real–world behaviour than standard fields. View OriginalDownload SlideView OriginalDownload Slide
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