Figure 1.

Variability of topographic parameters measured by coefficient of variation (CV). Graphs: top row = normal eyes, standard reference plane (ref plane); middle row = normal eyes, 320 μm reference plane; bottom row = glaucoma eyes, standard reference plane. Left column = intraoperator-intravisit testing, right column = interoperator-intervisit testing. Only standard reference plane analysis for glaucoma eyes shown (pattern in 320 μm reference plane data similar). Box plots = median, first, and third quartiles, error bars = 95% percentiles. Bar graphs = corresponding point estimates. X-axis: A = disc area, B = cup area, C = cup-disc area ratio, D = rim area, E = cup volume, F = rim volume, G = mean cup depth, H = maximum cup depth, I = cup shape measure, (*data were not analysed in glaucoma as cup shape values ranged from negative to positive, making it difficult to analyse CV meaningfully. Negative and positive values represent a skew towards low or high values in the height distributions of the cup respectively. Nevertheless, normal eyes gave a reasonable estimation of cup shape variability), J = retinal thickness, K = retinal cross sectional area.