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Paul H. Artes, David McLeod, David B. Henson; Response Time as a Discriminator between True- and False-Positive Responses in Suprathreshold Perimetry. Invest. Ophthalmol. Vis. Sci. 2002;43(1):129-132.
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purpose. To report on differences between the latency distributions of responses
to stimuli and to false-positive catch trials in suprathreshold
perimetry. To describe an algorithm for defining response time windows
and to report on its performance in discriminating between true- and
false-positive responses on the basis of response time (RT).
methods. A sample of 435 largely inexperienced patients underwent suprathreshold
visual field examination on a perimeter that was modified to
record RTs. Data were analyzed from 60,500 responses to suprathreshold
stimuli and from 523 false-positive responses to catch trials.
results. False-positive responses had much more variable latencies than
responses to suprathreshold stimuli. An algorithm defining RT windows
on the basis of z-transformed individual latency samples
correctly identified more than 70% of false-positive responses to
catch trials, whereas fewer than 3% of responses to suprathreshold
stimuli were classified as false-positive responses.
conclusions. Latency analysis can be used to detect a substantial proportion of
false-positive responses in suprathreshold perimetry. Rejection of such
responses may increase the reliability of visual field screening by
reducing variability and bias in a small but clinically important
proportion of patients.
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