A comparison of optic nerve head topography in primary open-angle glaucoma and normal-tension glaucoma in Korean

We investigated whether there is any difference in optic nerve head topography between primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG) in Koreans. Twenty-three eyes of 23 POAG and 20 eyes of 20 NTG Korean patients closely matched for mean deviation of automated static threshold perimetry (Humphrey Field Analyzer, program C30-2) were enrolled. The patients' mean age was 51.5 +/- 11.7 years in POAG and 55.1 +/- 10.6 years in NTG; the average mean deviation was -5.47 +/- 1.84 dB in POAG and -6.45 +/- 3.69 dB in NTG. Mean age and mean deviation were not statistically different between the two groups. Heidelberg Retina Tomograph was used to obtain topographic measurements of disc area, rim area, cup volume, cup-to-disc area ratio, mean cup depth, maximum cup depth, and cup shape measure. Disc area and cup volume were significantly larger in NTG than in POAG (p < 0.01, p = 0.03, respectively, Wilcoxon rank sum test). Other variables were not significantly different between the two groups. There was significant negative correlation between cup volume and rim area only in POAG (r = -0.725, p < 0.01, Spearman correlation analysis). These results suggest that the larger cup volume in NTG than in POAG may be influenced rather by larger optic disc in NTG not by smaller neuroretinal rim.