IOP was measured at 9:00 , 10:00 , 11:00 , 13:00 , 16:00 , 19:00 , 21:00 , 22:00 and 23:00 on day 1 , and 1:00 , 4:00 , 7:00 and 9:00 on day 2 in sitting position using Goldmann applanation tonometer .