PATTERN ERG IN EARLY GLAUCOMA DETECTION

Purpose Current electrophysiological techniques for diagnosis of glauc oma include pattern-electroretinogram (PERG) and visual evoked potenti als (VEP) but PERG has been recognized over the last decade as a good functional indicator of retinal ganglion cells. Methods Art investigat ion has been carried out on 171 eyes of 89 subjects using both PERG (g old foil electrodes) ana VEP. One group of 32 subjects with ocular hyp ertension (OHT) and another group of 27 subjects having simple chronic glaucoma (SCG) were compared with a control group of 30 healthy age-m atched subjects. Results For PERG, the amplitude of the P50 and N95 co mponents was measured but statistically significant differences were s hown for N95 only in SCG (p < 0.01) and OHT (p < 0.05). FFT analysis o n each PERG showed a dominant frequency of 3.3 Hz for OHT subjects ver sus 9.9 Hz for those of the control group. For VEP, the amplitude and latency of P100 was analysed. P100 latency showed significant delay (p < 0.05) in the SCG group only. Conclusions These findings suggest tha t N95-amplitude is the most sensitive electrophysiologic parameter for early glaucoma detection. By comparing data of this work with a previ ous study using wire (anchor shaped) electrodes we demonstrate higher amplitude and lesser variability of the N95 component for gold foil el ectrodes, therefore this latter type of recording is acknowledged as t he most sensitive for detection of early impairment of ganglion cells in HTO patients.