Purpose: Flicker defined form perimetry (FDF) and frequency doubling technology perimetry (FDT) are alleged to detect glaucoma at an earlier stage than standard automated perimetry (SAP). It is the purpose of this study to investigate the structure-function relationship between FDF, FDT, SAP, and confocal scanning laser ophthalmoscopy (cSLO) in patients with glaucoma.
Methods: Seventy-six patients with glaucoma were included in the study. Patients were tested with SAP, Matrix-FDT, FDF perimetry, and cSLO. Structure-function relationships between global and sectoral cSLO parameters and global and sectoral mean sensitivity (MS) of SAP, Matrix-FDT, and FDF were calculated using Spearman's rank correlation and linear regression.
Results: Overall, FDF perimetry showed the strongest structure-function relationship (GLOBAL correlation with rim area: 0.44; range of significant sectoral FDF values: 0.23-0.69), followed by FDT (global correlation with rim area: 0.35; range of significant sectoral FDT values: 0.25-0.60). SAP presented with the weakest structure-function relationship and fewer statistically significant results (global correlation with rim volume: 0.32; range of significant sectoral SAP values: 0.23-0.58). Sector-by-sector, the structure-function relationship was greatest in the superotemporal and inferotemporal regions. Weakest correlations were found in the inferonasal and nasal sectors.
Conclusions: The correlation between structure and function is stronger in FDF and FDT compared with SAP. Correlations are strongest in temporal areas where glaucomatous damage tends to occur first. A better understanding of the structure-function relationship should allow for improved detection and management of glaucoma patients.