Frequency Doubling Perimetry and Short-Wavelength Automated Perimetry to Detect Early Glaucoma

Abstract

To compare the ability of short-wavelength automated perimetry (SWAP) and frequency doubling perimetry (FDP) to detect early glaucoma damage. Prospective case-control study using a comparative case series. Forty-two patients with preperimetric glaucomatous optic nerve damage and a normal standard achromatic perimetry (SAP) in 1 eye, but with contralateral SAP abnormalities, and 35 normals. Forty-two patients and 35 normals underwent SWAP and FDP (Humphrey 24-2; Carl Zeiss Meditec, Inc., Dublin, CA). Correlations of mean deviation (MD) and pattern standard deviation (PSD) of the 2 groups were calculated. The number of defects at P<0.05 and P<0.01 on total deviation (TD) and pattern deviation (PD) plots were compared. Diagnostic precision and agreement on location of abnormalities were determined. Correlations and comparisons of global indices between SWAP and FDP: MD, PSD, TD, and PD abnormal number of points. Significant correlations in the glaucoma group were found between SWAP and FDP for MD (r = 0.54; P<0.008) and PSD (r = 0.49; P<0.001). Defects on the TD and PD plots were detected more frequently by FDP in the glaucoma group, although they were significant only for PD at P<0.01 (P = 0.024). Areas under receiver operator characteristic curves for MD of SWAP and PSD of FDP were 0.74 and 0.67, respectively (P = 0.37). Using defined defect criteria, FDP had a significantly higher sensitivity (72% vs. 54%; P = 0.02) and similar specificity (53% vs. 44%; P = 0.12) compared with SWAP. Agreement on defect location was moderate (kappa, 0.46). Testing time for SWAP was longer than for FDP in both glaucomatous and normal eyes (P<0.001). Short-wavelength automated perimetry and FDP showed similar ability to detect visual dysfunction in patients with preperimetric glaucoma. Long-term follow-up is required to define their role in predicting subsequent SAP defects.