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PH Artes, A Iwase, Y Ohno, Y Kitazawa, BC Chauhan; Properties of threshold estimates from Full Threshold, SITA Standard, and SITA Fast perimetry . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2145.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare the distributional properties of threshold estimates of SITA Standard, SITA Fast, and the Full Threshold algorithm, and to investigate the pointwise test/retest variability of these strategies. Method: Forty-nine patients (mean age, 61.6 yrs, range 22 - 81 yrs) with glaucomatous visual field loss (MD, mean -7.13 dB, range +1.76, -23.86 dB) attended for 4 sessions in one-week intervals. During each session, one randomly selected eye was examined with each of the 3 strategies, in random order. The SITA Standard and SITA Fast threshold distributions were compared to a 'best available' estimate of sensitivity, derived from the mean of 3 Full Threshold tests. Pointwise 90% retest limits (the 5th and 95th percentiles of the retest thresholds, stratified by initial threshold in steps of 2 dB) were derived to assess the reproducibility of individual threshold estimates. Results: The differences between SITA Standard, SITA Fast and the Full Threshold strategy varied non-linearly with sensitivity; they were largest (∼3 dB) for mid-range values of sensitivity (∼15 dB). The shapes of the threshold distributions of SITA Standard and SITA Fast varied considerably from that of the Full Threshold strategy. At field locations with sensitivities ≷25 dB, both SITA Standard and SITA Fast exhibited lower test/retest variability than the Full Threshold strategy. At locations with sensitivities <25 dB, the retest intervals of SITA Standard were slightly smaller than those of the Full Threshold strategy, whereas those of SITA Fast were larger. Conclusion: The systematic, non-linear differences between the threshold estimates of SITA and those of the Full Threshold strategy may be due to the a priori probability density functions used in SITA. These differences appear small compared to the pointwise test/retest variability. Compared to Full Threshold, SITA Standard showed slightly lower test/retest variability across the entire range of sensitivities, whereas SITA Fast gave more variable estimates when sensitivity was reduced.
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