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Abstract #3486 Published in IGR 4-2
Properties of perimetric threshold estimates from full threshold, SITA standard, and SITA fast strategies
Artes PH; Iwase A; Ohno Y; Kitazawa Y; Chauhan BCInvestigative Ophthalmology and Visual Science 2002; 43: 2654-2659
PURPOSE: To investigate the distributions of threshold estimates with the Swedish interactive threshold algorithms (SITA) standard, SITA fast, and the full threshold algorithm (Humphrey Field Analyzer; Zeiss-Humphrey Instruments, Dublin, CA) and to compare the pointwise testBretest variability of these strategies. METHODS: One eye of 49 patients (mean age, 61.6 years; range, 22B81 years) with glaucoma (mean deviation: mean, -7.13 dB; range, +1.8 to -23.9 dB) was examined four times with each of the three strategies. The mean and median SITA standard and SITA fast threshold estimates were compared with a 'best available' estimate of sensitivity (mean results of three full threshold tests). Pointwise 90% retest limits (fifth and 95th percentiles of retest thresholds) were derived to assess the reproducibility of individual threshold estimates. RESULTS: The differences between the threshold estimates of the SITA and full threshold strategies were largest (3 dB) for mid-range sensitivities (15 dB). The threshold distributions of SITA were considerably different from those of the full threshold strategy. The differences remained of similar magnitude when the analysis was repeated on a subset of 20 locations that are examined early during the course of a full threshold examination. With sensitivities above 25 dB, both SITA strategies exhibited lower testBretest variability than the full threshold strategy. Below 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. CONCLUSIONS: SITA standard may be superior to the full threshold strategy for monitoring patients with visual field loss. The greater testBretest variability of SITA fast in areas of low sensitivity is likely to offset the benefit of even shorter test durations with this strategy. The sensitivity differences between the SITA and full threshold strategies may relate to factors other than reduced fatigue. They are, however, small in comparison to the testBretest variability.
Dr. P.H. Artes, Department of Ophthalmology, Dalhousie University, Halifax, Nova Scotia, Canada
Classification:
6.6.2 Automated (Part of: 6 Clinical examination methods > 6.6 Visual field examination and other visual function tests)
