Example distributions of structural and functional data. The distribution of HFA Total Deviation at the point 3 degrees to the right and 15 degrees above fixation (A), and the distribution of the difference between measured and predicted rim area for the inferior-temporal sector of right eyes in the reference group (B). The same values from the glaucoma group are plotted in C and D. The line in each figure represents the cumulative probability function (CPF) for each distribution and helps to demonstrate the probability of normality concept used in the SFI calculation. Values to the left have low probabilities of normality (low values of the CPF) and values to the right have high probabilities of normality (high values of CPF).
Boland and Quigley BMC Ophthalmology 2011 11:6 doi:10.1186/1471-2415-11-6