Comparison of the 24-2 and 24-2C Visual Field Grids in Determining the Macular Structure-Function Relationship in Glaucoma

Abstract

Precis: The 24-2C grid showed significantly greater structure-function (S-F) associations in the global and regional sectors than the 24-2 visual field (VF) grid in open-angle glaucoma eyes. Purpose: The aim was to compare a Humphrey Field Analyzer (HFA) Swedish Interactive Threshold Algorithm-Faster (SITA-faster) 24-2C grid to a conventional HFA 24-2 grid regarding macular S-F relationships. Methods: The macular ganglion cell-inner plexiform layer thickness (mGCIPLT) was measured at different parafoveal sectors using spectral-domain optical coherence tomography in 150 eyes from 150 healthy, preperimetric, and perimetric glaucoma subjects. The central visual field mean sensitivity (VFMS) on the decibel and 1/L scales and the parafoveal mGCIPLT were matched topographically in 4 sectors and the strengths of the S-F relationships were assessed using "weighted" correlation coefficients and compared between 24-2C and 24-2 VF test grids. Results: There were significant global and sectoral correlations between the mGCIPLT and VFMS using both VF grids. The S-F correlations between the average/hemimacular mGCIPLT and the corresponding VFMS using a 24-2C grid were however significantly greater in both the entire and perimetric glaucoma groups (P<0.05), except for the average mGCIPLT of the perimetric glaucoma group in the 1/L scale (P=0.065). The 24-2C grid showed significantly greater S-F associations in the superotemporal and inferotemporal parafoveal sectors than the 24-2 VF grid (both P<0.05). Conclusions: A 24-2C grid may offer an advantage over the conventional 24-2 VF grid in assessing macular S-F relationships.