A) CB1 knockouts have lower baseline ocular pressure relative to WT controls. B) CB1 antagonist SR141716 (SR1) raises pressure at mid-day as expected in mice maintained in standard light cycle, but C) lowers IOP in reverse light cycle. D) SR1 has no effect in CB1 knockout males, but does lower IOP in females (E). A,E ***, p<0.001, unpaired t-test. B-C) *, p<0.05, p<0.01, paired t-test.