Progression patterns of normal-tension glaucoma groups classified by hierarchical cluster analysis

OBJECTIVES: To investigate differences in progression patterns of normal-tension glaucoma (NTG) patients in three clusters classified by hierarchical cluster analysis (HCA). MATERIALS AND METHODS: In a retrospective study, 200 eyes of NTG patients classified by HCA in 2015 who were followed up to the current date were evaluated. Peripapillary retinal nerve fibre layer (RNFL) thicknesses were measured by Cirrus HD-OCT and progression rate was calculated by trend analysis (Guided Progression Analysis [GPA]). VF progression rate was evaluated by linear regression analysis of mean deviation (MD). Progression patterns of three clusters were compared by histograms. RESULTS: In total, 153 eyes of 153 patients were followed up. Mean observation period was 5 years. RNFL reduction rate was −0.83 μm/year in cluster 1, which showed early glaucomatous damage in previous reports; −0.45 μm/year in cluster 2, which showed moderate glaucomatous damage; and −0.36 μm/year in cluster 3, which showed young and myopic glaucomatous damage. The progression pattern of cluster 3 showed a double-peak distribution; RNFL reduction rate was 0.11 μm/year in the non-progressive group and −1.07 μm/year in the progressive group. CONCLUSION: The progression patterns were different among three NTG groups that were divided by HCA. In particular, the group of young and myopic eyes showed a mixture of two different patterns.