Comparison of intraocular tonometry using three different non-invasive tonometers in children

Graefes Arch Clin Exp Ophthalmol. 2008 Oct;246(10):1463-6. doi: 10.1007/s00417-008-0863-y. Epub 2008 Jun 14.


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.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Anesthesia, General
  • Child
  • Child, Preschool
  • Glaucoma / congenital
  • Glaucoma / diagnosis*
  • Glaucoma / etiology
  • Humans
  • Infant
  • Intraocular Pressure*
  • Prospective Studies
  • Reproducibility of Results
  • Tonometry, Ocular / instrumentation*
  • Tonometry, Ocular / standards*