The S-Cone b-Wave of the Blue-on-Yellow Flash-Electroretinogram in Preperimetric Open-Angle Glaucoma

Abstract

Abstract: : Purpose: The S-cone b-wave of the flash-electroretinogram has been shown to be reduced in human primary open angle glaucoma by using a blue-green silent-substitution-technique on a red backbround (1). Aim of this pilot study was to evaluate whether the S-cone b-wave of the Blue-on-Yellow Flash-Electroretinogram (ERG) is affected in preperimetric open-angle glaucoma by using a conventional fullfield device. Methods: 23 eyes of 23 normals (59.1±9.6 years, MD<2.6 dB) and 15 eyes of 15 patients (55.6±7.2 years, MD<2.6 dB) with preperimetric open-angle glaucoma of the Erlangen-glaucoma-registry; preperimetric open-angle glaucoma means elevated intraocular pressure, glaucomatous optic disc damage but no defect in conventional white-on-white perimetry; age between normals and patients differed not significantly (p=0.205); subjects with opacity of the lens had been excluded by inspection of anterior segments and opacity lens meter; ganzfeld flash-electroretinograms (LKC, UTAS 3000) with blue Xenon-flashes (440 nm) of increasing photopic luminance (0.013, 0.018, 0.030, 0.052 cd s/m2 ) on a bright yellow background (550 nm; 238 cd/m2) were measured. Amplitudes and implicit times of S-cone b-wave were compared between glaucomas and normals (unpaired t-test). Results: The implicit times of the S-cone b-wave were significantly longer in preperimetric open-angle glaucoma for all flash intensities (p<0.05). Amplitudes of S-cone b-wave differed not significantly. Conclusion: The S-cone b-wave of the Blue-on-Yellow Flash-Electroretinogram might be a useful tool in early glaucoma diagnostics for testing the blue sensitive pathway of the retina. Advantages of this new method are the objectivity, the short examination time and the conventional device. (SFB 539) (1) Drasdo et al.. The S-cone PhNR and pattern ERG in primary open angle glaucoma. Invest Ophthalmol Vis Sci 2001; 42: 1266-72

Keywords: electrophysiology: clinical • retina • optic disc