Objectives To investigate image characteristics and thickness of the retinal nerve fiber la yer (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 3.4mm diameter circ le scan to calculate the RNFL thickness. Statistical analysis was used to compa re differences in RNFL thickness in quadrants and means between the normal and glaucomatous groups and the different stages of POAG. Linear correlation and reg ression analysis were used to show the correlation between RNFL thickness and vi sual field index of 115 eyes in glaucomatous patients. Reproducibility, sensiti vity and specificity of RNFL measurements using OCT were evaluated. Results RNFL thickness measured by OCT in normal subjects was thicker in superior and in ferior, less in temporal, and thinnest in nasal quadrants. The curve showed dou ble peaks. RNFL of glaucomatous patients showed local thinning or defect, diffu se thinning, or both. The mean RNFL thicknesses of the normal group in the temp oral, superior, nasal and infeior quadrants were 90.1±10.8μm, 140.4±10.5μm, 85.2±14.0μm, and 140.4±9.7μm, respectively with a mean of 114.2±6.0μm.The numbers for the glaucomatous group were respectively 56.0±31.0μm, 81.0±36.3μm, 47.1±27.5μm, and 73.4±38.4μm for th e four quadrants, with a mean of 64.6±28.8μm. There was a significant dif ference in RNFL thickness between the normal and glaucomatous groups (P<0.000), and the three stages (early, developing and late) of glaucomatous groups (P<0.000). There was a close negative relationship between RNFL thickness a nd visual field index (r=-0.796, P<0.0001). The sensitivity and speci ficity of RNFL thickness in POAG measured using OCT were 93.3% and 92.0%, res pectively. Conclusions OCT can quantitatively measure RNFL thickness differences between normal persons and glaucomatous patients. RNFL thickness gradually decreases while visual fie ld defect increases with the development of POAG.