Assessment of magnocellular function in patients with glaucoma or ocular hypertension by means of visual evoked potential

Abstract

We recorded VEPs elicited with new developed low spatial frequency, high temporal frequency and low contrast visual stimuli (M stimuli) to evaluate magnocellular function in both 8 patients with glaucoma or 5 patients with ocular hypertension and 13 normal subjects. VEPs were recorded from Oz electrodes, and analyzed with complex demodulation methods. Peak amplitudes were plotted as a function of the log of the stimulus contrast. The VEP contrast thresholds were determined by a linear extrapolation to zero amplitude. VEP peak amplitudes with 10% and 15% contrast stimuli were lower and contrast thresholds were higher in glaucoma group and ocular hypertension group (p<0.05). Contrast thresholds of 6 out of 13 patients were higher than the normal range. M stimuli-elicited-VEPs may be useful to evaluate the early functional impairment in patients with glaucoma or ocular hypertension.