Objective To evaluate a color contrast sensitivity test as a tool for the diagnosis of primary open angle glaucoma.Methods In a prospective case control study,82 eyes suspected of having primary open angle glaucoma served as the SOAG group; 80 primary open angle glaucoma eyes served as the POAG group; 75 normal eyes served as the control group.Color contrast sensitivity was measured with a Chroma Test.The SOAG group was followed up in 6 months.The thresholds of color contrast sensitivity were compared and the differences between and within the groups were statistically analyzed with a one-way ANOVA.In the SOAG group,the thresholds before and after six months were statistically analyzed with a paired t test.The consistency between the two methods was statistically analyzed with Kappa.Results ①The thresholds from high to low were compared for the POAG group,SOAG group and control group.There were significant differences between the POAG group and the control group (P＜0.01) in the protan and tritan axes.There was a significant difference in the lower temporal field and lower nasal field between the POAG group and the SOAG group.There were also significant differences in the upper temporal field,lower temporal field and upper nasal field between the SOAG group and the control group (P＜0.05).②During the 6 months of follow-up for the SOAG group,the threshold was higher comparing to the initial follow-up and there was a significant difference between the upper and lower temporal fields in the tritan axis (P＜0.05).The consistency between the two methods was good (Kappa=0.47).Conclusion Color contrast tests reveal a sensitivity to color change in the early stages of glaucoma.There was a good consistency between the visual field test and the chromatic test.Color contrast can be used in a screening program and to monitor patients who develop glaucoma.