Objectives To investigate image characteristics and thickness of the retinal nerve fiber layer (RNFL) in normal and glaucomatous eyes using optical coherence tomography (OCT), and analyze the relationship between RNFL thickness and visual field index.Methods Eighty-three normal persons (150 eyes) and 83 patients with primary open angle glaucoma (POAG, 149 eyes) underwent OCT examinations with 3.4 mm diameter circle scan to calculate the RNFL thickness. Statistical analysis was used to compare differences in RNFL thickness in quadrants and means between the normal and glaucomatous groups and the different stages of POAG. Linear correlation and regression analysis were used to show the correlation between RNFL thickness and visual field index of 115 eyes in glaucomatous patients. Reproducibility, sensitivity and specificity of RNFL measurements using OCT were evaluated.Results RNFL thickness measured by OCT in normal subjects was thicker in superior and inferior, less in temporal, and thinnest in nasal quadrants. The curve showed double peaks. RNFL of glaucomatous patients showed local thinning or defect, diffuse thinning, or both. The mean RNFL thicknesses of the normal group in the temporal, superior, nasal and infeior quadrants were 90.1 ± 10.8 lμm, 140.4 ± 10.5μm, 85.2 ± 14.0 μm, and 140.4 + 9.7 μm, respectively with a mean of 114.2 ± 6.0 μm. The numbers for the glaucomatous group were respectively 56.0 ± 31.0 μm, 81.0 ± 36.3 μm, 47.1 ± 27.5 μm, and 73.4 ±38.4 μm for the four quadrants, with a mean of 64.6 ± 28.8 μm. There was a significant difference in RNFL thickness between the normal and glaucomatous groups (P ＜ 0.000), and the three stages (early,developing and late) of glaucornatous groups (P ＜ 0.000). There was a close negative relationship between RNFL thickness and visual field index ( r = - 0.796, P ＜ 0.0001 ). The sensitivity and specificity of RNFL thickness in POAG measured using OCT were 93.3％ and 92.0％, respectively.Conclusions OCT can quantitatively measure RNFL thickness differences between normal persons and glaucomatous patients. RNFL thickness gradually decreases while visual field defect increases with the development of POAG.