Evaluation of the SITA Standard 24-2C visual field test

Abstract

Purpose : Some clinicians prefer to test their glaucoma patients with the SITA Standard strategy when performing visual fields. The recent SITA Faster 24-2C test for the HFA3 perimeter includes 10 points from the SITA 10-2 pattern tested at the end of the SITA Faster 24-2 threshold test. This preliminary study evaluated the central points of a new prototype SITA Standard 24-2C test.

Methods : Each normal and glaucoma subject took four tests on one eye at each of two visits with an HFA3 Model 860 perimeter (ZEISS, Dublin, CA): the prototype SITA Standard 24-2C, SITA Faster 24-2C, SITA Standard 10-2 and SITA Fast 10-2 test. Scatterplot and Bland-Altman (B-A) analysis were used to compare the mean deviation (MD) of the two 24-2C test strategies for both visits. The number of total deviation (TD) and pattern deviation (PD) points flagged for the 10 common points in the SITA Standard 24-2C and SITA Standard 10-2 tests were totaled and compared using paired equivalence t-tests (α = 0.05) for the second visit. The limits of equivalence were chosen to be +/- 2 points.

Results : Thirteen normal (mean age: 55.3 years, SD 7.7, range 44-69) and thirteen glaucoma (mean age: 70.5 years, SD 6.0, range 61-81) subjects were tested. The mean deviations (MDs) were similar between both strategies for normal and glaucoma subjects and illustrated for the glaucomas in Figure 1a & 1b. The number of flagged TD and PD P<0.05 points in the central 10 degrees between the 24-2C SITA Standard points and the SITA Standard 10-2 were statistically equivalent. For the normal group, the TD mean difference was 0.8 (SD: 0.5) points, the PD difference 0.9 (1.8) points while the glaucoma TD mean difference was 0.5 (0.9) and PD difference 0.4 (1.4) points (see Table 1).

Conclusions : The SITA Standard 24-2C test pattern showed a similar sensitivity to detect visual field loss in the new central 10-degree test locations as the SITA Standard 10-2 test. The SITA Standard 24-2C test may offer earlier detection of central visual field loss without the need to run a supplementary SITA 10-2. These results are similar to results from previous studies comparing the SITA Faster 24-2C and the SITA Fast 10-2 tests.

This is a 2020 ARVO Annual Meeting abstract.

 

Figure 1a & 1b: Linear regression and B-A plots for mean deviation (MD) of glaucoma patients (both visits)

 

Table 1: Mean number of flagged TD and PD points for normal and glaucoma subjects (visit two)