Evaluation of Changes in Intraocular Pressure with a Noncontact Tonometer in Healthy Volunteers

Figures & data

Table 1 Comparison of the Right and Left Eyes

Characteristics	Right Eye	Left Eye	p-value*
Refraction (D)	−3.40 ± 2.48 (−8.00 to 0.00)	−3.13 ± 2.49 (−8.00 to +2.00)	0.044
Cylinder (D)	−0.46 ± 0.40 (−1.50 to 1.50)	−0.55 ± 0.48 (−1.75 to 1.75)	0.095
Axial length (mm)	24.82 ± 1.61 (22.95 to 28.30)	24.79 ± 1.14 (22.60 to 26.91)	0.747
Radius of corneal curvature (mm)	7.78 ± 0.22 (7.30 to 8.16)	7.78 ± 0.22 (7.31 to 8.17)	0.900
Central corneal thickness (μm)	533.5 ± 42.0 (459.0 to 633.0)	534.1 ± 42.9 (463.0 to 633.0)	0.790
Intraocular pressure (mmHg)
Day 1	16.6 ± 2.3 (11.0 to 22.0)	16.2 ± 2.1 (10.3 to 21.0)	0.014
Day 2	16.9 ± 2.5 (11.3 to 22.7)	16.7 ± 2.4 (10.3 to 21.7)	0.201
Day 3	16.9 ± 2.9 (12.7 to 25.0)	17.2 ± 2.8 (13.0 to 23.0)	0.139
Day 4	16.9 ± 2.7 (12.3 to 23.0)	16.9 ± 2.7 (12.0 to 22.3)	0.829
Day 5	17.0 ± 2.7 (12.3 to 22.7)	16.9 ± 2.8 (11.0 to 23.0)	0.877

Notes: Data are expressed as mean ± standard deviation (ranges in parentheses). *Paired t-test.

Abbreviation: D, diopter.

Table 2 Intrasession Variability of Intraocular Pressure (mmHg) Measured at Least Thrice with a Noncontact Tonometer

	CV	ICC (95% CI)
Day 1 in the right eyes	0.056	0.927 (0.876–0.959)
Day 1 in the left eyes	0.045	0.951 (0.918–0.973)
Day 2 in the right eyes	0.047	0.960 (0.932–0.977)
Day 2 in the left eyes	0.044	0.961 (0.934–0.978)
Day 3 in the right eyes	0.049	0.962 (0.935–0.978)
Day 3 in the left eyes	0.058	0.913 (0.854–0.951)
Day 4 in the right eyes	0.048	0.956 (0.926–0.975)
Day 4 in the left eyes	0.051	0.955 (0.924–0.975)
Day 5 in the right eyes	0.043	0.965 (0.941–0.980)
Day 5 in the left eyes	0.046	0.966 (0.942–0.981)

Abbreviations: CV, coefficient of variation; ICC, intraclass correlation coefficient; CI, confidence interval.

Figure 1 Intraocular pressure (IOP) in the left eye, measured for 5 consecutive days with a noncontact tonometer. In the one-way repeated-measures analysis of variance, IOP was significantly lower on day 1 than on days 2 to 5 in the left eyes. *P < 0.05, **P < 0.01, ***P < 0.001.

Figure 2 Intraocular pressure (IOP) in the right eye, measured for 5 consecutive days with a noncontact tonometer. In the one-way repeated-measures analysis of variance, there were no significant differences among IOP values measured on days 1 to 5 in the right eyes.