Fig. 38. The change analysis printout of the Humphrey Statpac software. A. A normal box plot. B. Visual field progression has occurred over a series of five examinations performed within a period of 2.5 years. The box plots elongate and descend on the graph. The mean deviation and corrected pattern standard deviation decline. The mean deviation slope is negative and significant, indicating a statistically significant overall decline. (Haley MJ: The Field Analyzer Primer. San Leandro, CA: Humphrey Instruments, 1987.)