Frequency-Doubling Perimetry: Comparison With Standard Automated Perimetry to Detect Glaucoma

Abstract

To compare second generation frequency-doubling perimetry (FDP) with standard automated perimetry (SAP) to detect glaucomatous visual field abnormalities. Prospective, cross-sectional, controlled observational study. Fifty eyes of 50 patients with glaucoma with confirmed SAP visual field abnormalities and 42 eyes from 42 normal control subjects were studied. Swedish Interactive Thresholding Algorithm (SITA) standard 24-2 SAP and FDP visual fields were performed. The correlation of global indices and the number of defects on total deviation (TD) and pattern deviation (PD) plots were compared. The spatial concordance of FDP and SAP defect locations was determined. In patients with glaucoma, significant correlations of mean deviation (MD) and pattern standard deviation (PSD) were found between SAP and FDP (P < .001 for MD and P < .001 for PSD), but not in the normal group. FDP had significantly greater defect scores than SAP on total deviation and PD plots in the glaucoma group (P = .028 and P = .01, respectively). In comparison with SAP, sensitivity and specificity of FDP were 92% and 98% with glaucoma hemifield test criteria and 98% and 93% with PSD <5% criteria, respectively. Similarly high diagnostic precision was found with MD and PSD (at 95% specificity; MD and PSD sensitivity was 82% and 90%, respectively). The location of defects within 12 hemifield clusters found with FDP agreed moderately well with those detected with SAP (kappa = .48). FDP and SAP perform similarly in their ability to detect visual field defects in early to moderate glaucoma. Larger and deeper defects detected with FDP suggests the possibility of earlier detection at high specificity.