P 357
The photopic negative response of the flash electroretinogram in glaucoma patients
C. Cursiefen, F. Horn, M. Korth
Background: In unilateral macaque experimental glaucoma, following the positive b-wave, a photopic-negative response (PhNR) in flash electroretinograms (ERGs) was shown to be greatly reduced or absent compared to the healthy fellow eye. Aim of this study was to test whether this holds also true for human glaucoma patients.
Material and Methods: Photopic ganzfeld flash ERGs were recorded after 30 min of dark adaptation and subsequent 10 min of adaptation to a low background intensity (29.7 cd/m2) with fully dilated pupils using two test conditions. In condition I, using a background illumination of 0.47 cd/m2, 10 white Xenon-flashes were averaged (flash intensity 0.00587 cds/m2). In condition II, 6 red ganzfeld flashes on a rod-suppressing blue-adapting background (0.17 cd/m2) were averaged (flash intensity 0.0115 cds/m2). For condition I, 32 eyes of glaucoma patients (normal pressure glaucoma and primary/secondary open-angle glaucoma of the Erlangen Glaucoma Registry) and 12 eyes of normal controls were analyzed (condition II: 27 eyes of glaucoma patients and 10 eyes of normal controls, respectively).
Results: The amplitude of the PhNR was slightly reduced in glaucoma patients (condition I: -28 ± 29 µV; condition II: -17 ± 17 µV) compared to normal controls (condition I: -42.3 ± 35 µV; condition II: -74 ± 108 µV); but this difference was statistically not significant. Peak latency of PhNR did not differ significantly between glaucoma patients and controls.
Conclusions: Although the test conditions closely simulated the ones used in experimental animal glaucoma, no statistically significant reduction of PhNR in ganzfeld flash ERGs could be observed in glaucoma patients. Nevertheless there was a reduction of the amplitude of the PhNR in glaucoma patients compared to normal controls. Examination of PhNR does not seem to be useful in glaucoma diagnosis.
Augenklinik mit Poliklinik, Universität Erlangen-Nürnberg, Schwabachanlage 6, D-91054 Erlangen, Germany
Supported by DFG (SFB 539)