A Comparative Study between Swedish Interactive Thresholding Algorithm Faster and Swedish Interactive Thresholding Algorithm Standard in Glaucoma Patients

Abstract

Purpose: To compare the results of the new strategy Swedish Interactive Thresholding Algorithm (SITA) Faster to the results of SITA Standard in patients with glaucoma. Methods: This was a cross-sectional study of 49 patients with glaucoma and previous experience with standard automated perimetry. Two consecutive tests were performed in random order, one with SITA Standard and another one with SITA Faster, in the studied eye of each patient. Comparisons were made for test time, mean deviation (MD), visual field index (VFI), and number of depressed points in pattern deviation map and total deviation map for every level of significance. Results: The average test time was 56% shorter with SITA Faster ( P < 0.001). The intraclass correlation coefficient (ICC) for MD and VFI showed excellent agreement between both strategies, ICC = 0.98 (95% confidence interval [CI]: 0.96, 0.99) and ICC = 0.97 (95% CI: 0.95, 0.99), respectively. For the number of depressed points in total deviation map and pattern deviation map, ICC demonstrated good agreement with values between 0.8 and 0.95. Conclusions: Our study shows that SITA Faster is a shorter test with strong agreement with SITA Standard parameters. These results suggest that SITA Faster could replace SITA Standard for glaucoma diagnosis.

Visual fields in glaucoma: Where are we now?

“…Compared to its predecessor, SITA Standard (SS), the duration of visual field tests using the SITA Faster (SFer) algorithm reduces from an average test duration of 6.15–6.23 min in the older algorithm to 2.81–2.87 min. This time reduction of 53.5%–60.4% is the main advantage of using the newer SFer algorithm 14–18 . The disadvantage of having a shorter examination is evident as SFer has a 30.0%–49.7% rate of unreliable visual field results which is significantly higher than the SS rate at 10.8%–16.6%.…”

“…Most of these unreliable results stem from seeding point errors (low sensitivity measurements at one or more of the four primary test locations of the 24‐2 test grid) which lead to more severe global indices and increased clusters of threshold sensitivity reduction. Despite the differences between the two algorithms, the overall visual field parameters show good agreement, where the visual field index (VFI), foveal threshold, glaucoma hemifield test, and the number of depressed points on the deviation probability maps are similar 14,15,17,18 . Along with having similar test–retest variabilities, both SFer and SS have comparable visual field deficit sensitivities of 92.8% and 95.1% and specificities of 68.0% and 61.0%, respectively 14,17,19,20 .…”

“…This time reduction of 53.5%-60.4% is the main advantage of using the newer SFer algorithm. [14][15][16][17][18] The disadvantage of having a shorter examination is evident as SFer has a 30.0%-49.7% rate of unreliable visual field results which is significantly higher than the SS rate at 10.8%-16.6%. Most of these unreliable results stem from seeding point errors (low sensitivity measurements at one or more of the four primary test locations of the 24-2 test grid) which lead to more severe global indices and increased clusters of threshold sensitivity reduction.…”

“…While using the same 24‐2 pattern, this time reduction is achieved by seven modifications which include implementing age‐corrected initial stimulus intensities, reducing reversals at primary test points, adopting SF's Prior model, testing perimetric blind points once, removing false negative catch trials, using a gaze tracker, and eliminating extra delay times 13 . The two algorithms show no significant difference when it comes to MD, VFI, or the number of depressed points in their perimetry results 13,18 . However, SFer consistently shows smaller visual field deficits, making the results between the two algorithms uninterchangeable 13 .…”

“…17 Compared to SITA Fast (SF), which is the previous alteration of the SITA family, SFer reduces test durations by 30.4%-36.5%. 13,18 While using the same 24-2 pattern, this time reduction is achieved by seven modifications which include implementing age-corrected initial stimulus intensities, reducing reversals at primary test points, adopting SF's Prior model, testing perimetric blind points once, removing false negative catch trials, using a gaze tracker, and eliminating extra delay times. 13 The two algorithms show no significant difference when it comes to MD, VFI, or the number of depressed points in their perimetry results.…”