Abstract
Purpose:
To prospectively compare IOP measurements with the I-Care rebound tonometer with the Tonopen(Tp) and Pneumotonometer(Pm) in children under sedation and correlate measurements with the corneal diameter.
Methods:
Subjects: Children (under 5 years of age) with glaucoma (excluding those who underwent corneal surgery) (N=42), undergoing sedated eye exam and a control group without glaucoma (n=18) undergoing a sedated exam. The IOP was measured by three instruments: I-Care, Pm and Tp and the horizontal corneal diameter (Cd) recorded during the same sedated examination.
Results:
The age of the control group was 26.33 months+/-13.9(range 10-60 months). The mean Cd was average10.8+/-1.2mm (range 9-13 mm) IOP measured by I-Care, Pm and Tp in control were 13.9+/-3.38 mm Hg (range 8-20.), 15.9+/- 4.27mmHg (range 10- 27) and 14.76+/-3.25mmHg (range 10-21) respectively.Using Bland- Altman testing, the mean difference +/- 2 SD between the Tp and Pm was (-7.79, 5.44) with a correlation of 0.725 (p=.001). The mean difference +/- 2 SD between Tp and I care was (-5.06, 6.72) with a correlation of 0.620 (p=.008). The mean difference +/- 2 SD between Pm and I-care (-4.58, 8.59) with a correlation of 0.615 (p=.009). The Cd correlation with the IOP measured by I-care, Pm and Tp using Spearman’s correlation was as follows: 0.108 (p= .679), 0.120 (p= .645) and 0.139 (p= .594).In the glaucoma group the age was 26.05 months+/-14.8 month (range 2-48 months). The Cd was 12.7+/-1.5mmHg (range 8-17 mm). IOP measurements by I care, Pm and TP were 18.15+/-5.9 mm Hg, (range 8.1-31.5), 19.9+/- 6.7mmHg (7.5- 35.5) and 20.5+/-7.6 mmHg (range 5-43) respectively. Using Bland-Altman testing the mean difference +/- 2 SD between Tp and Pm was (-7.4, 8.76) with a correlation of 0 .835 (p=0.00). The mean difference +/- 2 SD between Tp and I-care was (-8.39, 13.10) with a correlation of 0.702 (p=.000). The mean difference +/- 2 SD between Pm and Icare (-8.57, 11.98) with a correlation of 0.607 (p=.000).The Cd correlation with the IOP taken by I-care, Pm, and Tp, using Spearman’s correlation was as follows: 0.003(p= .984),-0.100 (p= .529), -0.012(p= .940)
Conclusions:
IOP measurements using the three tonometers were comparable in both groups undergoing sedated eye exam. I-care IOP measurements appears to be least effected by corneal diameter.
Keywords: 568 intraocular pressure