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Comparison of intraocular tonometry using three different non-invasive tonometers in children
Julia Lasseck1, Thomas Jehle, Nicolas Feltgen
1University Eye Hospital Freiburg, Killianstrasse 5, 79106 Freiburg im Breisgau, Germany. julia.lasseck@uniklinik-freiburg.de
Insights
Accurate intraocular pressure (IOP) measurement is vital for childhood glaucoma. The Tono-Pen XL demonstrated superior accuracy compared to Schiötz and Perkins tonometers in pediatric patients.
Area of Science:
- Ophthalmology
- Pediatric Medicine
- Medical Devices
Background:
- Accurate intraocular pressure (IOP) measurement is critical for managing childhood glaucoma.
- Existing tonometry methods require evaluation for precision in pediatric populations.
Purpose of the Study:
- To compare the accuracy of Tono-Pen XL, Schiötz, and Perkins tonometers against direct intraocular pressure measurements in children with glaucoma.
Main Methods:
- Intraocular pressure was measured in 20 pediatric glaucoma patients under general anesthesia.
- Non-invasive applanation (Tono-Pen XL, Perkins) and indentation (Schiötz) tonometry were compared to direct intraocular measurements.
- Linear regression and coefficient of variance (CV) were used for data analysis.
Main Results:
- The Tono-Pen XL showed the lowest coefficient of variance (10%) and a high coefficient of determination (r²=0.74).
- Perkins (19% CV, r²=0.78) and Schiötz (17% CV, r²=0.60) tonometers underestimated intraocular pressure.
- Tono-Pen XL readings demonstrated homogeneous scattering around the true intraocular pressure.
Conclusions:
- The Tono-Pen XL provided the most accurate estimation of intraocular pressure among the tested devices in pediatric glaucoma patients.
- This finding supports the Tono-Pen XL as a preferred tonometer for IOP assessment in this demographic.
Background:
In childhood glaucoma, the correct determination of intraocular pressure (IOP) is crucial in clinical decision-making. We therefore investigated how intraocular tonometry readings correlate with readings from commonly used tonometers.
Methods:
IOP was measured unilaterally in 20 children suffering from congenital (n = 7) or secondary glaucoma (n = 13), 10 minutes after the induction of general anaesthesia. The children were aged from 1 month to 17 years (mean age 4.3 years, median age 1.3 years). Non-invasive applanation (Tono-Pen XL, Perkins tonometer) and indentation tonometry (Schiötz tonometer) were performed in random order prior to intraocular tonometry with a 26-gauge needle connected to a pressure sensor. Linear regression analysis and the coefficients of variance (CV) were used to compare the data obtained from the various tonometers.
Results:
Compared with intraocular pressure, the CV was 10% for the Tono-Pen XL, 17% for the Schiötz, and 19% for the Perkins tonometer. The coefficient of determination (r(2)) was 0.74 for Tono-Pen XL, 0.60 for Schiötz and 0.78 for Perkins tonometry. The IOP values obtained with the Tono-Pen XL scattered homogeneously around the intraocular IOP, while the Perkins and Schiötz tonometers underestimated intraocular measured IOP.
Conclusion:
Of the three tonometers evaluated in this series of paediatric glaucoma patients, the Tono-Pen XL most closely reflected true IOP.