Table 3.

Differences between ultrasound pachymetry, noncontact tonopachy, Pentacam, and RTVue.

Parameter	TP-USP	Pen-USP	RTVue-USP	Pen-TP	RTVue-TP	RTVue-Pen
Mean bias in CCT (μm)	1.22	12.29	0.28	11.08	−0.94	−12.01
SD (μm)	5.47	5.87	5.32	6.54	5.78	6.87
Maximum (μm)	15	30	18	28	14	7
Minimum (μm)	−12	−2	−9	−7	−14	−26
95% CI for the mean (μm)	−0.02 to 2.45	10.97 to 13.62	−0.92 to 1.48	9.60 to 12.55	−2.24 to 0.37	−13.56 to -10.47
LOA (μm)	−9.50 to 11.93	0.78 to 23.81	−10.14 to 10.70	−1.75 to 23.90	−12.27 to 10.39	−25.47 to 1.44
Width of limits (μm)	21.43	23.03	20.84	25.65	22.66	26.91
95% CI for the LOA	−11.61 to 14.04	−1.49 to 26.07	−12.19 to 12.75	−4.28 to 26.43	−14.5 to 12.63	−28.12 to 4.09
P (one-way ANOVA, Bonferroni)	0.316	<0.01	1.000	<0.01	0.941	<0.01
R-value	0.988	0.986	0.988	0.981	0.986	0.980
Within 5-μm difference (%)	73.1	10.3	71.8	19.2	69.2	17.9

ANOVA = analysis of variance, CCT = central corneal thickness, CI = confidence interval, LOA = limits of agreement, Pen = Pentacam, SD = standard deviation, TP = tonopachy, USP = ultrasound pachymetry.