Hierarchical cluster analysis of peripapillary retinal nerve fiber layer damage and macular ganglion cell loss in open angle glaucoma

Purpose: To categorize the structural progression pattern of glaucoma, as detected by optical coherence tomography guided progression analysis, with respect to the peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer (GCIPL). Methods: One hundred sixty-four eyes with primary open-angle glaucoma were studied. The structural progression pattern evaluated by optical coherence tomography guided progression analysis was classified using hierarchical cluster analysis. The clinical parameters, patterns of structural progression, and visual field (VF) changes were compared among the groups. Results: Three groups were included: stable, progressive peripapillary RNFL thinning without macular GCIPL involvement, and progressive thinning of both the peripapillary RNFL and macular GCIPL. The third group, those with progressive peripapillary RNFL and macular GCIPL thinning, showed more progressive peripapillary RNFL thinning in the inferotemporal area and VF progression in the parafoveal area. Conversely, the 12 and 6 o'clock areas were the most common locations of progressive peripapillary RNFL thinning in the group without macular GCIPL involvement. Conclusions: Structural progression patterns of glaucoma can be categorized into three groups. The location of progressive peripapillary RNFL thinning is associated with progressive macular GCIPL thinning and pattern of VF changes in the affected area. Our results indicate that the use of only macular GCIPL analysis is inadequate for analyzing the structural progression of glaucoma.