Comparison of detectability of visual field abnormality by frequency doubling technology in primary open-angle glaucoma and normal-tension glaucoma.

PURPOSE To compare the effectiveness of frequency doubling technology (FDT) in detecting abnormalities in primary open-angle glaucoma (POAG) and in normal-tension glaucoma (NTG). METHODS Twenty-nine POAG patients (29 eyes) and 27 NTG patients (27 eyes) were studied. All subjects underwent testing with program C-20 of FDT with appropriate corrective lenses. RESULTS No significant differences were observed between the two groups in mean age, mean deviation (MD), and pattern standard deviation (PSD) measured by the Humphrey Field Analyzer (HFA). The correlation between MD values determined by HFA (x) and FDT (y) is represented by y = 0.60x - 2.7 (r = 0.78, P <.01) in the POAG group and y = 0.59x + 0.6 (r = 0.81, P <.001) in the NTG group. Although the average MD measured by FDT was significantly lower in the POAG group than in the NTG group (P <.05), no significant difference was found in average PSD between the two groups. In early glaucoma cases (MD > or = -5 dB by HFA), a larger proportion of cases in the POAG group than in the NTG group had lower significance level of MD determined by FDT than by HFA (P <.02). At many test points on the temporal periphery in the FDT, the mean sensitivity was lower in the POAG group than in the NTG group; whereas no significant differences among HFA test points were observed. CONCLUSIONS Frequency doubling technology detected visual field abnormalities in POAG cases more sensitively than in NTG cases. This finding indicates that the pathogenesis of My-cell damage is rather different in POAG and NTG.