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Accuracy of Intraocular Pressure Measurement With the Icare Tonometer in Children
Wai Hong Chan1, I Chris Lloyd, Richard J Symes
1From the *Department of Paediatric Ophthalmology and Strabismus, Kettering General Hospital, Northamptonshire and †Department of Paediatric Ophthalmology and Strabismus, Manchester Royal Eye Hospital, Manchester, United Kingdom.
Insights
The Icare tonometer (IT) may overestimate intraocular pressure (IOP) in children, especially those with anterior segment pathology (ASP). Further research is needed to establish correction factors for accurate IOP measurement in pediatric patients.
Area of Science:
- Ophthalmology
- Pediatric Ophthalmology
- Biomedical Engineering
Background:
- Accurate intraocular pressure (IOP) measurement is crucial for diagnosing and managing pediatric eye conditions.
- Existing tonometry methods may have limitations in pediatric populations, particularly those with ocular abnormalities.
Purpose of the Study:
- To compare intraocular pressure (IOP) measurements obtained with the Icare tonometer (IT) against standard methods (applanation, pneumatic, and digital tonometers) in children.
- To evaluate the potential overestimation of IOP by the IT in pediatric patients, with a focus on those with anterior segment pathology (ASP).
Main Methods:
- A randomized prospective trial involving children under 16 years old was conducted.
- Intraocular pressure (IOP) was measured twice in each child using the Icare tonometer (IT) and one other tonometer (applanation, pneumatic, or digital) during the same clinic visit.
- Data analysis included calculating mean difference (MD), range (R), positive bias (PB), and limits of agreement (LOA) between the IT and other devices.
Main Results:
- The study included 44 children (88 eyes), with a mean age of 57 months.
- The Icare tonometer (IT) showed a tendency to overestimate IOP compared to other tonometers, with a mean difference (MD) ranging from 1.4 to 3.2.
- In eyes with anterior segment pathology (ASP), the IT demonstrated a higher mean difference (MD = 3.9) and positive bias (PB = 3.9) compared to the pneumatic tonometer (PT).
Conclusions:
- The Icare tonometer (IT) may overestimate intraocular pressure (IOP) measurements in children, particularly those with anterior segment pathology (ASP).
- A positive bias of up to 4 mm Hg was observed, with potential overestimations of up to 8 mm Hg in some cases with ASP.
- Larger cohort studies are recommended to establish reliable correction factors for IT IOP measurements in pediatric populations, especially those with ocular abnormalities.
Purpose:
The aim of this study was to evaluate the difference between intraocular pressure (IOP) measurements in children with the Icare tonomer (IT) and applanation (AT), pneumatic (PT), or digital tonometers (TT).
Design:
A randomized prospective trial of children younger than age 16 attending the pediatric ophthalmology department of Manchester Royal Eye Hospital was conducted.
Methods:
Children had IOP measured twice, once with an IT and again with a TT, PT, or AT during the same clinic appointment.
Results:
Forty-four children (88 eyes) were included, with a mean [range (R)] age of 57 (2-144) months. Twelve eyes had anterior segment pathology (ASP), defined as aniridia, congenital glaucoma, or Peters anomaly. Regardless of the presence or absence of ASP, total mean difference (MD), R, positive bias (PB), and limits of agreement (LOA) between IT and other instruments were as follows: PT: MD = 3.2, R = 0 to 8, PB = 2.9, LOA = -1.0 to 6.9; TT: MD = 2.6, R = 0 to 6, PB = 0.9, LOA = -1.8 to 3.5; and AT: MD = 1.4, R = -3 to 5, PB = 0.6, LOA = -4.2 to 7.3. In eyes with ASP, IT comparisons with PT were as follows: MD = 3.9, R = 0 to 8, PB = 3.9, LOA = -0.9 to 8.8.
Conclusions:
In children with ASP, IOP measured with IT is higher than expected when compared with other tonometers, in some cases by up to 8 mm Hg. We found an overestimation of IOP in children using the IT with a positive bias of 4 mm Hg. We propose that the IT overestimates IOP measurements in children compared with standard tonometers. Further work should be carried out on a much larger cohort to establish a suitable correction factor for such children.
