The effects of transitioning from SITA-Standard to SITA-Fast or SITA-Faster on sensitivities below the measurement floor

Objective

Determine how sensitivities below the measurement floor of the Humphrey Field Analyzer change when transitioning from Swedish Interactive Thresholding Algorithm (SITA) Standard to SITA-Fast and SITA-Faster strategies.

Design

Retrospective descriptive study

Participants

A total of 21,468 24-2 SITA-Standard, 4872 SITA-Fast and 3468 SITA-Faster VFs from 7917 glaucoma and glaucoma suspect eyes with at least 5 VFs between 1997 and 2023 at the Wilmer Eye Institute.

Methods

At each test location of the 24-2 test pattern, we measured the probability that <0 dB at a given test location on two baseline SITA-Standard VFs was M dB or higher on the first SITA-Fast or SITA-Faster post-baseline VF for different values of M > 0. Results were compared to using the same test strategy for both baseline and post-baseline VFs.

Main outcome measures

Probability of <0 dB at baseline being measured as M > 0 dB or higher on the first post-baseline VF.

Results

At M = 7 dB, which was approximately one standard deviation above the mean for post-baseline SITA-Standard sensitivities, average percent change from <0 dB across all test locations was 10.3 % for SITA-Standard, 15.8 % for SITA-Fast and 25.5 % for SITA-Faster. Percent change from <0 dB for all M tested (up to M = 20) was consistently higher near the macula compared to overall averages: on average 1.3 % higher for SITA-Standard, 1.5 % higher for SITA-Fast, and 6.3 % higher for SITA-Faster.

Conclusions

Increased caution is advised when following the progression of <0 dB defects during a transition from SITA-Standard to SITA-Fast or SITA-Faster.