Comparison of frequency doubling perimetry and standard achromatic computerized perimetry in patients with glaucoma

Purpose: To evaluate the reproducibility and efficacy of frequency-doubling perimetry (FDP), a new perimetric method for the detection of functional glaucomatous damage. Methods: Thirty-four glaucomatous eyes of 34 patients were examined by FDP (using the complete N30 threshold test of the Humphrey Frequency Perimeter) and by standard achromatic computerized perimetry (SAC; using the full threshold program 30-2 of the Humphrey Field Analyzer). Twenty-six of these eyes were examined twice by FDP. Reproducibility of repeated FDP was tested by the difference and the average of mean deviations (MD). Efficacy was studied by comparison of FDP and SAC using MD, as well as threshold results of FDP and corresponding SAC-tested areas. Spearman's rank correlation was calculated. Results: A significant correlation of repeated FDP examinations was found regarding MD [r=0.94, P<0.00001 (n=26)]. The reproducibility of FDP was independent of the glaucomatous damage [r=0.04, P=0.85 (n=26)], based on the correlation of the difference, and the average of MD. The MD of FDP and that of SAC showed a significant correlation [r=0.87, P<0.00001 (n=34)]. In advanced glaucoma, FDP tended to yield lower measurement values than SAC. Regarding corresponding areas, there was a significant correlation between threshold results of FDP-tested areas and the corresponding SAC testpoints [r=0.92, P<0.00001 (n=34)]. The conformity decreased from the peripheral to the central tested visual field. Conclusions: Sufficient reproducibility of FDP could be demonstrated in early and advanced glaucomatous visual field defects. Conformity between FDP and SAC was shown in terms of MD and threshold results of FDP-tested areas and corresponding SAC testpoints.