The diurnal phasic variations in intraocular pressure have been known for a long time. Maslenikow is credited with their first description and many subsequent workers have confirmed his findings. Köllner's1 work first showed the significance of this phasic change during the day and Thiel2 showed that the intraocular pressure rises more steeply between the hours of 5 A.M. and 7 A.M., is followed by a fall in the intraocular pressure in the morning, and a further fall in the late afternoon. Duke-Elder3 states that in the great majority of normal people the diurnal variations seldom exceed 5 mm. of Hg Schiøtz, the highest pressure occurring generally in the early morning, thus showing the opposite trend from the diurnal variations in vascular blood pressure.
In patients with chronic simple glaucoma, the diurnal variations become exaggerated and the intraocular pressure becomes labile at a stage of the disease when
DRANCE SM. The Significance of the Diurnal Tension Variations in Normal and Glaucomatous Eyes. Arch Ophthalmol. 1960;64(4):494-501. doi:10.1001/archopht.1960.01840010496004