Various global indices are available to summarize results from standard automated perimetry. This study asks which index can detect significant deterioration earliest, for a fixed specificity.

Comparison of prognostic indices.

Two cohorts were tested. A test-retest cohort contained 5 reliable visual fields, within a short interval, from 45 eyes of 23 participants with glaucoma and/or likelihood of developing glaucoma. A separate longitudinal cohort contained 508 eyes from 330 participants, tested on average 13 times. Three global indices were extracted: mean deviation (MD), pattern standard deviation (PSD), and visual field index (VFI). For each index we defined a critical P value Crit_Index, such that 5% of test-retest series showed significant deterioration with P < Crit_Index, using artificial “test dates” in random order. Therefore these criteria have 95% specificity over series of 5 tests. The times to detect significant deterioration in the longitudinal cohort were compared using a survival analysis model.

The median time to detect significant deterioration with MD was 7.3 years (95% confidence interval [CI] 6.8–7.9 years). For VFI, the median was 8.5 years (95% CI 7.9–9.0 years); this comparison had P = .088. For PSD, the median was 10.5 years (95% CI 9.3–11.7 years), slower than MD with P < .001. Within the first 5 years of a series, MD detected significant deterioration in 138 eyes, vs 104 for VFI (P = .0013) and 107 for PSD (P = .029).

MD detected significant deterioration sooner than VFI or PSD. In particular, MD detected more eyes in the first 5 years of their follow-up, which were presumably undergoing more rapid progression.