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Paul G. D. Spry, Alex B. Bates, Chris A. Johnson, Balwantray C. Chauhan; Simulation of Longitudinal Threshold Visual Field Data. Invest. Ophthalmol. Vis. Sci. 2000;41(8):2192-2200.
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purpose. To describe and evaluate a computer model that simulates longitudinal
visual field data.
methods. A computer model was designed using factors that influence thresholds
of normal and glaucomatous visual fields. The simulation model was used
to quantify the effects of fluctuation on the outcomes of pointwise
linear regression by comparison with simulated gold standard data with
results. Serial sets of 10 stable and 10 progressive visual fields with
different fluctuation levels were generated by simulation and were
analyzed using pointwise linear regression. Regression outcome measures
used were slopes of −1 dB/year or worse and slopes of −1 dB/year or
worse that were also statistically significant. In stable visual
fields, the number of locations with regression slopes worse than −1
dB/year increased with fluctuation and defect size and was inversely
related to the number of fields. The number of locations with
statistically significant slopes remained low and appeared unaffected
by these variables. In progressive visual fields, analysis of a small
number of visual field test results (<8) overestimated the number of
locations with regression slopes worse than −1 dB/year and
underestimated the number of locations with statistically significant
conclusions. Computer simulation may be used to provide a gold standard outcome that
permits evaluation of statistical tools for monitoring progressive
glaucomatous visual field loss.
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