Biomechanically-Corrected Intraocular Pressure Compared To Pressure Measured With Commonly Used Tonometers In Normal Subjects

Figures & data

Table 1 Mean And Standard Deviation (SD) Of Measured IOP Using Different Tonometers (n=94 Eyes)

Methods	Mean±SD (mmHg) (95% CI)	Range (mmHg)	Pairwise Comparisons
Icare (a)	14.59±3.40 (13.89, 15.29)	6.00–22.00	a, d: 1.000 Other pairs: <0.001
GAT (b)	13.08±2.64 (12.54, 13.62)	8.00–20.00
Corvis, bIOP (c)	16.11±1.66 (15.76, 16.45)	13.00–23.40
ORA, IOPcc (d)	15.01±2.55 (14.49, 15.54)	7.80–20.90

Abbreviations: IOP, Intraocular pressure; 95% CI, 95% Confidence interval; GAT, Goldmann applanation tonometer; bIOP, Biomechanically-corrected IOP; ORA, Ocular response analyzer; IOPcc, Cornea-compensated IOP.

Figure 1 Agreement of the bIOP with the IOP measured using Icare (upper), GAT (middle) and IOPcc (lower). (n=94 eyes) The mean difference is shown by a solid horizontal line, while the 95% limits of agreement, zero mean difference and the regression line are indicated by dashed horizontal and oblique lines, respectively.

Table 2 Mean And Range Of Differences Between bIOP And Other IOP Measurements In mmHg, And 95% Limits Of Agreement (n= 94 Eyes)

Methods	Mean Difference±SD (95% CI)	Range	95% Limits Of Agreement (1.96 × SD of differences)	ICC	Spearman Correlation
Icare - bIOP	−1.51±2.95 (−2.11, −0.90)	−9.30, 7.00	−7.29, 4.27 (±5.78)	0.507 p< 0.001	0.482 p< 0.001
GAT - bIOP	−3.02±2.60 (−3.55, −2.50)	−10.40, 5.00	−8.11, 2.07 (±5.09)	0.279 p= 0.001	0.351 p= 0.001
IOPcc - bIOP	−1.09±1.96 (−1.49, −0.69)	−6.20, 3.70	−4.93, 2.75 (±3.84)	0.686 p< 0.001	0.557 p< 0.001

Abbreviations: IOP, Intraocular pressure; 95% CI, 95% Confidence interval; GAT, Goldmann applanation tonometer; bIOP, Biomechanically-corrected IOP; IOPcc, cornea-compensated IOP; ICC, intra-class correlation coefficient.

Table 3 Mean And Standard Deviation Of IOP (mmhg) In Small (<540 µm) And Large (≥540 µm) Central Corneal Thickness (n=94)

CCT IOP	<540 µm (n=54)	≥540 µm (n=40)	P-value
	Mean±SD (95% CI)	Mean±SD (95% CI)
Icare	13.70±3.12 (12.85, 14.55)	15.80±3.43 (14.70, 16.89)	0.001
GAT	12.81±2.89 (12.02, 13.60)	13.45±2.25 (12.72, 14.17)	0.211
Corvis, bIOP	15.77±1.02 (15.49, 16.05)	16.55±2.20 (15.85, 17.26)	0.165
ORA, IOPcc	14.67±2.60 (13.96, 15.38)	15.48±2.44 (14.69, 16.26)	0.129*

Note: *Parametric statistics.

Abbreviations: IOP, Intraocular pressure; GAT, Goldmann applanation tonometer; bIOP, Biomechanically-corrected IOP; ORA, Ocular response analyzer; IOPcc, cornea-compensated IOP; CCT, Central Corneal Thickness.