Glaucoma follow-up when converting from long to short perimetric threshold tests

OBJECTIVES: To study the influence of test length in automated perimetry follow-up of glaucomatous eyes and, particularly, to determine if it is possible to usefully interpret test results obtained using a testing algorithm shorter than that used for baseline testing.

METHODS: Automated perimetry findings were retrospectively evaluated in 31 patients with glaucoma for whom multiple Humphrey 30-2 tests were available on the Full Threshold strategy and the SITA Standard strategy.

RESULTS: Variability around the mean deviation regression lines was smaller with SITA than with the Full Threshold strategy. Mean deviation values with SITA averaged about 1 dB less severe. Although localized scotomas measured in decibels were deeper on the Full Threshold strategy, number of significantly depressed points on total deviation and pattern deviation probability plot analyses did not differ significantly between the 2 strategies.

CONCLUSIONS: The SITA strategy showed test-retest consistency that was at least as good as that of the Full Threshold strategy. The 2 strategies produced similar results when analyzed relative to their respective normal significance limits. Generally, it is appropriate to establish a new baseline when converting from one perimetric algorithm to another. When necessary, however, results may be usefully compared if such comparisons are based on total and pattern deviation probability maps rather than on decibel values.