Ability of 24-2C and 24-2 Grids to Identify Central Visual Field Defects and Structure-Function Concordance in Glaucoma and Suspects

PURPOSE: The purpose of this study was to compare the ability of the 24-2 test grid with that of the 24-2C test grid to measure visual field global indices, identify central visual field defects, and facilitate macular structure-function analysis with optical coherence tomography (OCT) scans in glaucoma suspects and glaucoma patients. DESIGN: Prospective, cross-sectional study. METHODS: One eye from each of 100 glaucoma suspects and glaucoma patients (60 undergoing SITA-Faster [Zeiss Meditec] testing on 24-2 and 24-2C; 40 undergoing SITA-Standard [Zeiss Meditec] testing on 24-2 and SITA-Faster on 24-2C) were included in the study. Global visual field indices, test duration, and pattern deviation results were extracted. The deviation map from the Cirrus OCT (Carl Zeiss Meditec) Ganglion Cell Analysis (GCA) was extracted, and structure-function relationships were compared after correction of the visual field test stimulus location that stimulated the corresponding retinal ganglion cell. RESULTS: Global index results of the 24-2 grid were similar to those of the 24-2C grid, and both identified a comparable number of clusters of visual field defects. Centrally, the 24-2C grid identified more clusters of defects than the 24-2 grid, but this was not statistically significant. Although the 24-2C test locations resulted in more instances of structure-function concordance than the 24-2 locations, half the locations in the 24-2C grid fell close to or outside the GCA grid when corrected for ganglion cell displacement. CONCLUSIONS: The 24-2C returned global visual field indices similar to the 24-2 grid but tended to identify more clusters of central functional defects. Central structure-function concordance was better achieved using the 24-2C grid, but half of the visual field test locations did not coincide with the commonly used macular thickness scan.