Inter-subject variability and normal limits of the SITA standard, SITA fast, and the Humphrey full threshold computerized perimetry strategies, SITA STATPAC

Purpose: To establish and evaluate inter-subject variability and normal thr eshold limits for the new SITA strategies and to compare them with those ob tained with the traditional Humphrey Full Threshold algorithm. Methods: Data from 330 eyes of 330 normal subjects were collected at 10 cen tres in order to establish limits of normality for the new SITA strategies and thus, to make it possible to subject SITA fields to computer-assisted v isual field analysis. Two, visual field tests were obtained with each of th e SITA Standard, SITA Fast, and the Full Threshold algorithms. Results: Inter-subject variance was 31% smaller with SITA Standard and 41% smaller with SITA Fast than with Full Threshold (p < 0.0001). Age-dependent decrease of differential light sensitivity was also significantly smaller with both SITA algorithms than with Full Threshold (p < 0.0001), 23% and 25 % respectively, Mean sensitivity was somewhat higher with both SITA Standar d (29.5 dB) and SITA Fast (29.9 dB) as compared to Full Threshold (28.3 dB) (p < 0.0001). Normal limits were tightened between 9 to 29% at different s ignificance levels with SITA, Conclusion: SITA test results from eyes with normal visual fields will on a verage be more even from centre to mid-periphery as compared with Full Thre shold fields They will also appear slightly lighter in grey-scale represent ations, Because of smaller inter-subject variance, shallower depressions ar e needed in SITA fields for statistical and clinical significance.