Comparing a parallel PERG, automated perimetry, and frequency-doubling thresholds.

PURPOSE

A pattern electroretinogram (PERG) simultaneously displaying the frequency-doubling (FD) illusion in nine parts of the visual field was compared with two other methods for ability to detect glaucoma. This multiregion FD PERG (MFP) was compared with results from achromatic automated perimetry and psychophysical tests using FD stimuli.

METHODS

MFP data were compared with that from the Humphrey Field Analyser (HFA; Humphrey, San Leandro, CA) 24-2 program. Contrast thresholds were also determined in different visual field locations for FD stimuli. Thin-plate spline methods were used to derive comparisons from the tests, each of which sampled the visual field differently.

RESULTS

Significant correlation with HFA could be obtained, providing seven to nine (of nine) MFP amplitudes were themselves significant. Evidence showed that both the psychophysical tests using FD stimuli and the MFP detect glaucomatous damage not detected by the HFA.

CONCLUSIONS

The comparisons between HFA perimetry, the MFP, and FD thresholds indicate that both FD-based tests quantify a form of diffuse loss in early glaucoma as well as the scotomas of later glaucoma.