Fig. 8

Multivariate statistical analysis. A Principal component analysis for GFAP, RBPMS, NEFL and IBA1 immunoreactivity demonstrated that > 85% of the variance in the data was contributed by the first 2 principal components, as indicated in the Scree plot. B Score plot from factor analysis showing that maximal variance was weighted by 3 factors: RBPMS, NEFL and IBA1, with the former 2 representing neuronal components, and the latter representing a glial component. C Cluster analysis using the principal components. Severity of glaucoma was assessed by applying the Calinski-Harabasz criterion for unbiased k-means clustering using the expression values for RBPMS, NEFL, and GFAP positive staining. Non-glaucomatous donors clustered in 2 distinct groups while glaucomatous tissues clustered in 3 distinct groups (mild, moderate, and severe). Arrows as indicated in the figure identify tissues with qualitative cupping of the ONH observed through histology