Table 2.

Comparison of 24-hour intraocular pressure (IOP) measurements based on optic disc appearance (habitual position)

Period	IOP parameter	Concentric Mean (SD) mm Hg	Non-concentric Mean (SD) mm Hg	P value
Diurnal	Mean	20. (3.6)	19.8 (2.6)	0.40
	Peak	23.7 (4.4)	23.4 (3.3)	0.69
	Trough	17.4 (3.5)	16.8 (2.6)	0.29
	Range	6.2 (2.0)	6.1 (2.7)	0.55
Nocturnal	Mean	24.0 (3.7)	21.9 (1.9)	0.004 *
	Peak	26.0 (4.2)	23.7 (2.5)	0.008 *
	Trough	22.0 (3.4)	20.1 (1.8)	0.02 *
	Range	4.1 (2.4)	3.6 (1.7)	0.20
Office	Mean	20.9 (3.9)	20.3 (2.5)	0.50
	Peak	22.2 (4.0)	22.3 (3.2)	0.90
	Trough	18.9 (3.9)	18.7 (2.4)	0.79
	Range	3.6 (1.7)	3.5 (1.8)	0.85
24-hour	Mean	21.6 (3.5)	20.5 (2.2)	0.11
	Peak	26.6 (4.5)	24.9 (2.3)	0.050
	Trough	17.5 (3.5)	16.6 (2.4)	0.21
	Range	6.2 (2.0)	6.6 (2.7)	0.55
Nocturnal-Diurnal	Mean	3.5 (3.1)	2.1 (2.1)	0.021*

^*P < 0.05

SD = Standard Deviation