Related Experiment Video
Updated: Aug 14, 2026
Evaluation of Capnography Sampling Line Compatibility and Accuracy when Used with a Portable Capnography Monitor
Published on: September 29, 2020
[Comparative study between the non-contact pneumotonometer Canon TX10 and the Goldmann tonometer]
H Sánchez-Tocino1, R Bringas-Calvo, D Iglesias-Cortiñas
1Departamento de Oftalmología, Hospital Río Hortega de Valladolid, España. hsanchez@auna.es
Purpose:
To study and contrast the measurement of intraocular pressure (IOP) with an air non-contact tonometer (Canon TX-10) with that obtained with the Goldmann tonometer.
Methods:
Intraocular pressure was measured in 649 subjects with both the pneumotonometer and the Goldmann tonometer. Statistically significant differences between the results obtained by both tonometers and the influence of variables including age, corneal thickness, and corneal curvature were studied.
Results:
The mean age of the study population was 48.5 years, standard deviation (SD) 7.6 years, with a range of 22-68 years. The mean IOP was 15.4, SD 2.7 mm Hg, (range 8-25) with the Goldmann tonometer and 15.6, SD 2.9 mm Hg (range 8-29) with the pneumotonometer. There was a statistically significant difference between the measurements using the air pneumotonometer and the Goldmann tonometer (p<0.001). The mean of the differences between both tonometers was 0.24, SD 2 mm Hg. Seventy-five percent of measurements were in the range of +/-1, 85% in +/-2, and 95% in the Bland and Altman's interval of 4.42, -3.94. These differences were more significant for higher values of IOP, in thicker corneas and in corneas with greater curvature. A correlation between IOP and age was not found (p=0.247).
Conclusions:
The pneumotonometer is a useful and reliable instrument for measuring the IOP providing there is additional checking in cases with borderline values of IOP, or excessive corneal thickness and/or curvature.
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