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David B. Henson, Shaila Chaudry, Paul H. Artes, E. Brian Faragher, Alec Ansons; Response Variability in the Visual Field: Comparison of Optic Neuritis, Glaucoma, Ocular Hypertension, and Normal Eyes. Invest. Ophthalmol. Vis. Sci. 2000;41(2):417-421.
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purpose. To compare the relationship between sensitivity and response
variability in the visual field of normal eyes and eyes with optic
neuritis (ON), glaucoma (POAG), and ocular hypertension (OHT).
methods. Frequency-of-seeing (FOS) data were collected from four visual field
locations in one eye of 71 subjects (12 ON, 25 POAG, 11 OHT, and 23
normal), using a constant stimulus method on an Henson 4000 perimeter
(Tinsley Instruments, Croydon, UK). At each location, at least 20
stimuli (subtending 0.5°) were presented for 200 ms at six or more
intensities above and below the estimated threshold. The mean and SD of
the probit fitted cumulative Normal function were used to estimate
sensitivity and response variability. Cluster regression analysis was
carried out to determine whether there were differences in the
sensitivity-log (variability) relationship between the four groups.
results. Variability was found to increase with decreased sensitivity for all
four groups. The combined data from the four groups was well
represented (R2 = 0.57) by the function
log e (SD) = A·sensitivity
(dB) + B, where the constants A and B were −0.081 (SE, ±0.005) and 3.27 (SE, ±0.15),
respectively. Including other statistically significant covariates
(false-negative errors, P = 0.004) and factors
(diagnosis, P = 0.005) into the model increased the
proportion of explained variance to 62%
(R 2 = 0.62). Stimulus eccentricity
(P = 0.34), patient age (P =
0.33), fixation loss rate (P = 0.10), and
false-positive rate (P = 0.66) did not reach
statistical significance as additional predictors of response
conclusions. The relationship between response variability and sensitivity is
similar for ON, POAG, OHT, and normal eyes. These results provide
supporting evidence for the hypothesis that response variability is
dependent on functional ganglion cell density.
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