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D. B. Henson, M. A. Miranda; Perimetric Sensitivity and Response Variability in Glaucoma With Single Stimulus and Multiple Stimulus Presentations. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1618.
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To measure perimetric sensitivity and response variability (frequency-of-seeing slope) of glaucomatous patients with single stimulus (SS) and multiple stimulus (MS) presentations.
Frequency-of-seeing (FOS) data were collected from four visual field locations (normal and reduced sensitivity) in one eye of 10 glaucoma patients, using a SS and a MS test strategy. The SS technique was similar to that used in routine clinical perimetry while the MS technique required the patient to verbally report the positions of the seen stimuli (0-4 with no more than 1 in each quadrant) after each presentation. At each test location, stimuli (0.5°, 200ms) were presented at five or more intensities above and below the estimated threshold. FOS curves (logistic) were determined using a maximum likelihood method and the threshold sensitivity (50% seen) and response variability (20-80% seen range) were compared between the two different strategies.
There was a increase in sensitivity (mean=1.9dB, p<0.01, Wilcoxon) and reduction in variability (range reduced from 3.7 to 2.5dB, p<0.01, Wilcoxon) with the MS strategy. The reduction in sensitivity with the MS technique varied between patients (p<0.001, one way ANOVA) with some patients showing very little difference between the 2 strategies while others showed a large difference (mean MS-SS sensitivity per eye range -0.29 to 5.68dB).
Patients have a higher sensitivity and less variability in their visual field when tested with a MS rather than a SS strategy. These differences vary between patients and are most likely caused by better maintenance of attention with the MS technique. This highlights the role of attention as an important cause of response variability with clinical perimetry.
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