Measuring intraocular pressure (IOP) in children can be a challenge particularly if repeated measurements are required.
Children with congenital glaucoma, congenital cataracts, anterior segment dysgeneses, aniridia, Sturge Weber syndrome, uveitis or those on steroid eye drops need to have repeated IOP measurements.
The gold standard for IOP measurement is the Goldmann applanation tonometer and a variant of this method, the handheld Perkins tonometer, was widely used in paediatric ophthalmology. This improved with the Tonopen, however, many children were uncooperative and examination needed to be performed under general anaesthesia. The anaesthetic drugs or mask/ventilation could affect the IOP reading leading to high but often lower readings.
This challenge of paediatric IOP measurement was revolutionised by the advent of the rebound tonometer from iCare. This has allowed children to be measured in the clinic and reduced the number of children needing examinations under anaesthesia just for IOP.1
There are numerous studies that have compared the different devices, usually in clinic patients, with variable levels of correlation and often noting that the iCare may over-estimate IOP.2
There was little data on the range of IOP measured by iCare in the general population and very little data on repeated measures over time. As the iCare is now widely used measure of IOP in paediatric practice, it is important to establish the normal range of IOP in children measured with the iCare and to assess the repeatability over time for this measurement.
Although we can now provide a newborn baby their genetic risk for developing glaucoma in adult life, we do not know when we need to initiate examination or intervention in at-risk individuals.
With the 2023 Quinlivan Research Grant from Glaucoma Australia, we are now evaluating the third generation of the Raine study in Western Australia. We had previously examined parents in generation two for numerous eye diseases and related biometry including IOP.3
This study, also involving co-investigator and Postdoctoral Research Fellow Dr Samantha Lee, will examine IOP using the iCare in 200 children every six months for a total of three years.
The results of this research will be a population distribution of iCare IOP in children as well as a measure of how constant this is over time.
We will also examine young adults to determine IOP pressure changes through early adult life and whether genetic risk influences pressure at a young age.
This will enable never-before-possible research into the genetic, lifestyle and intergenerational aspects of IOP, as well as the creation of an IOP reference range for children. It will also improve our ability to monitor children and young adults at high risk of developing glaucoma and allow more timely intervention with the aim of decreasing glaucoma blindness.
For more information on the Raine Study, visit rainestudy.org.au/ and rainestudy.org.au/second-leading-cause-of-blindness/
About the authors
Names: Prof David A Mackey; Dr Samantha Lee
Qualifications: MD FRANZCO; PhD
Affiliations: University of Western Australia, Lions Eye Institute Perth (both)
Location: Perth (both)
Years in industry: 35; 7
More reading
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A hard look at surgical waste – Dr Michael Loughnan & Dr Sukhpal Sandhu
References
1. Grigorian F et al. The use of the iCare tonometer reduced the need for anesthesia to measure intraocular pressure in children. J AAPOS 2012;16:508-510
2. Julia D, Tan S. Intraocular pressure measurements in paediatric glaucoma: A narrative review on accuracy, tolerability, and ease of use. Med J Malaysia. 2024;79:206-211.
3. Lee SS et al. Rationale and protocol for the 7- and 8-year longitudinal assessments of eye health in a cohort of young adults in the Raine Study. BMJ Open. 2020 Mar 25;10(3):e033440.
