“…Studies in humans and dogs described a diurnal variation in tear turnover rate 5,6 . In the study of other physiological parameters, the pattern of diurnal variation was found to be affected by a number of endogenous and exogenous factors such as age, 7,8 season, 9–11 feeding times and fasting, 12–14 isolation, 15 exercise, 16,17 electro‐magnetic field, 18,19 change in light intensity and environmental temperature 10 . Normal STT has recently been shown to be affected by age, gender, time of day, season, environmental condition and placement of strips 20,21 .…”