The Swedish Interactive Threshold Algorithm (SITA) Faster (SFR) test may save considerable time in obtaining visual field (VF) measurements in patients with manifest or suspect glaucoma, but a research team from India suggests this method still needs further amendments before it’s accurate enough to replace SITA Fast (SF) or SITA Standard (SS).
SS and SF 24-2 tests use gaze tracking, blind spot check and false-negative catch trials, whereas SITA Faster 24-2 tests are run with gaze tracking engaged but without blind spot check and false-negative catch trials.
The study, published in the Journal of Glaucoma, compared the three methods’ test time, mean deviation (MD), pattern standard deviation (PSD), VF index, foveal threshold, number of points depressed on a PSD probability plot, individual threshold test points, glaucoma hemifield test (GHT) and grade of field defect.
A total of 70 eyes of 70 patients were included in this study.
The researchers found SITA Faster test times were approximately 36.1% shorter than SF and 60.7% shorter than SS. However, the additional findings bring the new tool’s accuracy into question:
- MD values were lower with SITA Faster compared with SF and SS.
- Mean PSD and VF index showed no significant differences between the algorithms.
- Mean foveal threshold was higher for SITA Faster compared SF and SS.
- The number of points depressed at p<0.5% was less in SITA Faster than in both SF and SS.
- Bland–Altman plots showed considerable variability between the algorithms.
SITA Faster provides benefits in test time and shows similar VF indexes compared with SITA Fast and SITA Standard; however, detection of early cases with SITA Faster is questionable, and a few modifications are needed in the future to improve its accuracy, the researchers said.
As a side note, the researchers found SITA Fast and SITA Standard gave almost similar results.
However, “the algorithms cannot be used interchangeably for the same patient on different test sessions,” the researchers noted in their paper.
Patyel S Thulasidas M. Comparison of 24‑2 faster, fast, and standard programs of Swedish interactivethreshold algorithm of Humphrey field analyzer for perimetry in patients with manifest and suspect glaucoma. J Glaucoma. September 3, 2020. [Epub ahead of print].