Abstract
Abstract: :
Purpose: The photopic negative response (PhNR) of the flash-electroretinogram has been shown to be reduced in human primary open angle glaucoma by using red flashes on a blue background (Viswanathan et al. 2001). This pilot study evaluates whether the PhNR of the flash-electroretinogram (ERG) with white flashes on a white background is affected by glaucomatous damage, too. Methods: ERG was performed in 10 patients aged 18-67 years with advanced asymmetrical glaucomas (1x angle-closure glaucoma, 2x primary open-angle glaucoma, 3x secondary open-angle glaucoma, 4x normaltension glaucoma). The interocular difference of perimetric defects (mean deviation) was ≷ 4dB between the two fellow eyes (white/white-perimetry, Octopus 500, G1-3). White flashes (xenon discharge tube, Ganzfeld stimulator) of increasing photopic luminance (1.47, 1.89, 2.09, 2.32, 2.58 and 3.33 log phot td s) were used on a white background (2,5 log phot td). The amplitudes of a-wave, b-wave and the PhNR for all flash intensities were compared interocularly using the paired-t-test. Correlations were computed between interocular differences of mean deviation and amplitudes of a-wave, b-wave and PhNR using Pearson`s correlation coefficient. Results: Amplitudes of the a-wave were significantly lower in the more damaged eyes only for the flash intensity 1.47 log phot td s. Amplitudes of the PhNR were significantly reduced in the more damaged eyes for the two flash intensities 1.47 and 2.09 log phot td s. There was no significant difference in amplitudes of b-waves between the two fellow eyes. The interocular differences in the mean deviation correlated significantly with the interocular differences in the a-wave amplitudes for flash intensities of 1.47, 1.89 and 2.09 log phot td s, and in the PhNR amplitudes for flash intensities of 1.47, 1.89, 2.09 and 2.32 log phot td s. Conclusion: The photopic negative response as well as the a-wave are significantly reduced in glaucomatous damage using the white-on-white-flash-electroretinogram.
Keywords: 395 electroretinography: clinical