[Chronic open angle glaucoma: correlation of pattern electroretinography and visual field indices]

The pattern electroretinogram has already proven to be useful in detecting early stages of chronic open-angle glaucoma. We were interested in the degree of correlation between pattern ERG amplitudes and definite visual field defects. Fifteen glaucoma patients with a wide range of visual field defects were examined with pattern electroretinogram (stimulus with reversal rate of 8/s, checksizes of 0.9 degree and 6.9 degrees, covering a visual field of up to 9 degrees eccentricity). The patients' visual fields obtained with the Octopus 1-2-3 perimeter were analyzed with the perimetric analysis system PERIDATA using the indices of conformity for localized defects and the regional indices created from the mean deviation in certain parts of the 30 degrees field. In our results we were only able to find a significant correlation within the 5% level between the pattern ERG amplitudes and the sector index (large checksize, correlation coefficient r = -0.58, p = 0.03) and with the mean deviation in the region between 10 degrees and 20 degrees (small checksize, r = -0.538, p = 0.044). In summary, a marginal correlation between electrophysiological data and perimetric parameters was demonstrated. We try to explain the remarkable correlation between the amplitudes (small pattern) that were recorded from the central 9 degrees with the mean defects from the visual field peripheral of 10 degrees with the frequent combination of diffuse and localized field defects in glaucoma. Examination with the pattern ERG alone does not seem to be appropriate for grading the focal glaucomatous damage.