Assessment of measurements
To evaluate the potential future use of the various methods used in this study, the dispersion of measurements and their responsiveness to change were assessed. The coefficient of variation (CV) is used as a standardized measure of data dispersion, that is, the larger the CV (%), the less consistent the data. In this study, the CV is a measure of both biological variation and the inherent error of each measurement technique. The day 1 CVs of all measurements used in this study were calculated to assess which measurements exhibited the greatest consistency and thus may be of greatest utility in a future study.The responsiveness to change was examined a posteriori by comparing the change in each measure at the end of day 5 from baseline on day 1 with the change in LV measured by perometry in group A as the gold standard (as this demonstrated a significant reduction over this time).