Aim: To determine if retinal ganglion cell (RGC) loss influences the loss of surrounding RGCs to generate clustered patterns of cell death in human glaucoma. We hypothesise that retinal ganglion cell loss accelerates the loss of surrounding cells to generate, at a local, cellular scale, clustered patterns of retinal of RGC death; the absence of these interactions would result in a diffuse pattern of RGC loss.
Method: Six glaucomatous retinas and six age-matched control retinas were prepared as wholemounts and stained by 4',6-diamidino-2-phenylindole solution (3μg/mL). An area corresponds to central 14 degree of the visual field was imaged. The nearest neighbour distribution was determined for cells in both normal and glaucomatous RGCL.
Results: We observed clustered RGC loss in human glaucoma on a background of diffuse loss. The mean nearest neighbour distance (NND) of the glaucomatous retinas was significantly higher compared with controls (p<0.001). The distribution of NND in glaucomatous retinas was skewed to the higher values with a higher positive kurtosis relative to controls. The quantitative analysis of the pattern of cell loss is supported by the visual inspection of the patterns of cell loss.
Discussion: Nearest neighbour analysis is consistent with the presence of two patterns of cell loss in the RGCL in glaucoma. While the diffuse of cell loss can account for an overall reduction in the RGC population and additional non random pattern is consistent with the hypothesis that RGC loss has a local influence on the viability of surrounding cells.