Figure 2 of Liu, Mol Vis 2011; 17:1405-1413.

Figure 2. Circadian IOP fluctuation of conscious Tibetan monkeys. IOP was measured by the TonoVet® rebound tonometer at the indicated times of the day. Data of two studies conducted three days apart on the same animals are presented together: the first study monitored IOP from 9 AM to 9 PM; the second, from 9 PM to 9 AM Symbols represent mean±SEM (n=12; both eyes of 6 animals).