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

Abstract

Objectives To investigate differences in progression patterns of normal-tension glaucoma (NTG) patients in three clusters classified by hierarchical cluster analysis (HCA). Materials and methodsIn 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.

Rate of Change in Bruch’s Membrane Opening-Minimum Rim Width and Peripapillary RNFL in Early Normal Tension Glaucoma

“…The ROC in the present study for those with early NTG was −0.956 ± 0.160 µm/yr for global RNFL and −2.063 ± 0.649 µm/yr for global BMO-MRW. The ROC of RNFL showed similar rate with those reported in previous studies [16,21], which was also less than −1.0 µm/yr. However, the ROC of BMO-MRW, a new parameter, showed much greater rate than that of RNFL.…”

“…In a previous study that calculated the ROC of RNFL in Asian (Korean) cohorts that included predominantly NTG, the ROC of RNFL was −0.71 (−0.94; −0.48) µm/yr in early stage of glaucoma (baseline MD: −2.48 ± 4.46 dB) [16]. In a recent study of Korean subjects, the reduction rate of RNFL from early NTG cluster group was −0.83 µm/yr with baseline MD of −3.19 ± 4.13 dB [21]. Therefore, it might not be so easy to see a change of glaucomatous progression with RNFL, which was less than −1.0 µm/yr in the early stage of NTG.…”