IOP changes with increasing Age. Mean IOP ± SEM is shown for the indicated strain at different ages. IOP decreased significantly in strains C57BL/6J and 129P3/J but not C3H/HeJ. The C57BL/6J and 129P3/J groups consisted of approximately equal numbers of males and females. The 3 months old C3H/HeJ mice were male while the other ages were composed of males and females. The number of mice analyzed at each age, listed from youngest to oldest, follow: C57BL/6J, 18, 18, 18, 18, 13; 129P3/J, 18, 15, 16, 14, 21; C3H/HeJ, 15, 23 17 and 16.