AIM:To score disc damage likelihood scale(DDLS)in primary open angle glaucoma(POAG)using Heidelberg retina tomography-Ⅲ(HRT-Ⅲ)and to determine if DDLS score is better than cup/disc ratio(C/D)values in reflecting the extent of visual field defects in POAG.METHODS:A total of 56 POAG patients were included in this study.It was in double-blind case to determine C/D values.After the OCTOPUS-900 perimeter(G2-TOP)and HRT-Ⅲ examination,the value of vision mean defect(MD)were recorded.According to the topographic map of HRT-Ⅲ,DDLS score of the optic disc for subjects was gained.Results were evaluated with Pearsons correlation coefficient.RESULTS:Large optic disc(optic disc area of 3.09-3.43mm2)of 9 eyes,medium-sized disc(2.41-2.67mm2)34 eyes and small optic disc(1.64-1.81mm2)13 eyes were included in the analysis.DDLS was strongly associated with MD(total:Pearson r=0.916,P<0.01;large disc:Pearson r=0.850,P=0.0037,medium-sized optic disc:Pearson r=0.934,P<0.01;small disc:Pearson r=0.912,P<0.01).C/D had moderate correlation with the MD(total:Pearson r=0.676,P<0.01;large disc:Pearson r=0.472,P=0.199,medium-sized disc:Pearson r=0.682,P<0.01;small disc:Pearson r=0.788,P=0.0014).CONCLUSION:Using HRT-Ⅲ to do DDLS staging for POAG optic disc has better grade in the extent of optic nerve damage than the C/D.