Comparison of 24-2C SITA Standard intervisit repeatability to legacy SITA tests

Abstract

Purpose : The 24-2C test pattern increases sensitivity to central field defects by adding 10 test locations from the 10-2 pattern that are tested at the end of a 24-2 threshold test¹. The purpose of this ongoing, preliminary clinical study was to compare the repeatability of the 10 added test locations in a prototype 24-2C SITA Standard test to legacy SITA tests in normal and glaucomatous eyes.

Methods : Experimental 24-2C SITA Standard (SS-C), as well as 24-2C SITA Faster (SFR-C), 10-2 SITA Standard (SS-10), and 10-2 SITA Fast (SF-10) visual fields (VFs) were acquired on an HFA3 Model 860 perimeter (ZEISS, Dublin, CA) at each of two visits on one eye each for healthy and glaucomatous subjects. 24-2 SITA Standard VFs were extracted from SS-C as a reference for disease severity.

Repeatability was calculated by computing the test-retest standard deviation (TRT-SD) using both visit data for mean deviation (MD) and pattern standard deviation (PSD), as well as individual threshold values at the 10 added test locations.

Results : Mean age was 55.8 (standard deviation, SD: 6.4; range: 44.3 to 69.9) years for 17 healthy eyes and 73.6 (SD: 9.2; range 60.9 to 97.9) years for 16 glaucomatous eyes (p<0.001). Mean 24-2 SITA Standard MD was 0.63 (SD: 1.15; range: -1.14 to 3.04) dB and -6.81 (SD: 6.86; range: -22.61 to 1.85) dB in healthy and glaucomatous eyes (p<0.001), respectively.

TRT-SDs for MD were 0.61, 1.29, 0.52, and 0.49 dB for tests SS-C, SFR-C, SS-10, and SF-10, respectively.
TRT-SDs for the 10 added locations were 1.57, 2.28, 1.85, 2.21 dB for tests SS-C, SFR-C, SS-10, and SF-10, respectively (see Table 1). Overall, the repeatability for SS-C MD and thresholds were comparable to their counterparts.

Conclusions : The findings in this preliminary cohort suggest the repeatability of the additional test locations added to 24-2C SITA Standard test is comparable to the repeatability of the same locations in the 24-2C SITA Faster and the 10-2 SITA tests. As a result, a 24-2C SITA Standard test may maintain comparable ability to detect progressive changes in the ten new test locations in the central visual field as compared to the current SITA tests.

References
[1] Callan et al. IOVS 2020; 61(7): Abstract 3876

This is a 2021 ARVO Annual Meeting abstract.

 

Table 1. TRT-SD and 95% confidence interval for thresholds in the 10 new test locations