Both the pattern electroretinogram (PERG) and computerized disc analysis have been shown to detect early stages of glaucomatous optic nerve disease. As these two methods tap different domains (PERG reflects ganglion cell function, whereas disc analysis yields morphometric measures), we set out to compare their results in the same eyes. We recorded the PERG and optic disc parameters in 114 eyes of 58 ocular hypertensive patients. In addition, 51 eyes (26 patients) were monitored over a follow-up period of more than 6 months using the optic nerve-head analyzer. We found: (1) that a reduction in PERG amplitude was significantly correlated with increasing loss of neuroretinal rim area (P < or = 0.01), (2) that 9 of 11 eyes with a significant (P < 0.1) decrease in neuroretinal rim area over time had a reduced PERG, and (3) no significant correlation between PERG and optic disc area or between PERG and rim area. Our data show a high agreement between PERG amplitude and computerized disc analysis. This encourages the hope that it will be possible to detect glaucoma damage before appreciable visual field defects ensue.