120 eyes of normal subjects, 150 eyes of ocular hypertension, and 132 eyes of primary open angle glaucoma (POAG) were examined the retinal nerve fiber layer (RNFL), neuroretinal rim area (NRA), visual field, dark adaptation and pattern reversal visual evoked potential (PVEP), revealing that RNFL defect and NRA correlated with visual field defect, threshold of dark adaptation and latency of PVEP. RNFL examination using red free photographic technique yielded 96% sensitivity in glaucoma detection and 95% specificity in identifying normal eyes. Modified semiquantitative criterion for assessing RNFL defect had a good reproducibility. The mean NRA in normal eyes was 2.22 +/- 0.35 mm2. Therefore, 95% of the normal subjects had rim areas greater than 1.64 mm2; 82% of patients with POAG had NRA less than 1.64 mm2. 20.1% of the eyes of ocular hypertension had RNFL defect and 37.6% had NRA below the 95% lower point, suggesting that some patients with increased intraocular pressure could have structural abnormalities. The authors proposed that ocular hypertension without visual field defect but with significant RNFL defect and/or NRA decrease should be regarded as in a preliminary stage of POAG.