Confidence intervals for change in automated visual fields.

Abstract

SUMMARY Three successive fields of 136 eyes (86 patients) were extracted from our data base containing over 3000 visual fields performed on the Humphrey visual field analyser with program 30-2. Series of fields in which the second field was depressed relative to the first were selected for analysis to determine how much change between the first two fields was required to predict a downward trend as confirmed by the third field in the series. The data were stratified with respect to initial field damage. Seven regions of the visual field were analysed including the upper and lower temporal and nasal quadrants, the superior and inferior Bjerrum regions, and the whole field. Minimally damaged regions required between 4-7 and 5 6 dB change in mean sensitivity, whereas more damaged regions required between 5-5 and 7*2 dB change in mean sensitivity to have 95% confidence that the negative trend would be confirmed by the third field. The superior Bjerrum region was the most sensitive for the detection of change, and the lower temporal region was the least sensitive. We conclude from this series of data that large changes between two successive fields are required to be sure that the changes are due to disease rather than chance fluctuation. Where any doubt exists, the field should be repeated to confirm the reality of change.

Long‐term follow‐up of baseline learning and fatigue effects in the automated perimetry of glaucoma and ocular hypertensive patients

“…The results of Wild et al (1989) and of the current study support the hypothesis of Hoskins et al (1988) in that baseline fields performed within a short period of time may provide a better indication for the recognition of subsequent change. Due to the presence of a small but statistically significant learning effect and to the evidence for an interest fatigue effect, total reliance should not be placed upon the absolute values of the visual field indices and reliability parameters derived from the initial (full) field examinations determined by automated perimetry in suspected or actual glaucomatous field loss.…”

A perimetric nerve fiber bundle map

“…Any effort to divide the visual field into sectors and areas related to the retinal nerve fiber bundles [4][5][6][7][8] had to be based solely on anatomical studies. But such studies are complicated and results vary, as Ballantyne's overview showed [9].…”

Variability in glaucomatous visual fields: implications for shared care schemes

“…For example, if the cut o criteria was initially set to give a false positive rate of 10% (90% probability level, see Table 1) then repeating the test with the same criteria, the patient being required to be beyond the 90% probability level on both tests, would reduce the false positive rate to 1% (the square of its value). It is for this reason that several researchers have advocated duplicate measures (Hoskins et al, 1988;Schultzer, 1994) when trying to distinguish between noise and progressive loss. The Normal Tension Glaucoma Study (Schultzer, 1994), which was designed to detect the smallest degree of progression, found that a single stage cut o value produced unrealistically large numbers of progressors.…”