Comparison of Tono-Pen and Goldmann applanation tonometers for measurement of intraocular pressure in healthy children.

PubMed ID: 22459105

Author(s): Bradfield YS, Kaminski BM, Repka MX, Melia M; Pediatric Eye Disease Investigator Group, Davitt BV, Johnson DA, Kraker RT, Manny RE, Matta NS, Schloff S, Weise KK. Comparison of Tono-Pen and Goldmann applanation tonometers for measurement of intraocular pressure in healthy children. J AAPOS. 2012 Jun;16(3):242-8. doi: 10.1016/j.jaapos.2011.12.150. Epub 2012 Mar 28. PMID 22459105

Journal: Journal Of Aapos : The Official Publication Of The American Association For Pediatric Ophthalmology And Strabismus, Volume 16, Issue 3, Jun 2012

PURPOSE To assess the agreement of intraocular pressure (IOP) measured with the Tono-Pen and the Goldmann applanation tonometer (GAT) in normal children and adolescents.

METHODS A total of 439 subjects from birth to <18 years of age without anterior segment anomalies or glaucoma had their IOP measured with the two instruments by separate, masked examiners in the office or under general anesthesia.

RESULTS On average, the Tono-Pen measured values slightly lower than the GAT for IOP 11 mm Hg in the office setting. Using the average of GAT and Tono-Pen IOPs to estimate the true IOP, the average difference (GAT – Tono-Pen) was 0.4 mm Hg at IOP of 10 mm Hg and -3.0 mm Hg at IOP of 20 mm Hg. The 95% limits of agreement on the average difference between instruments were ± 6.4 mm Hg in the office setting and ± 6.8 mm Hg under general anesthesia. Larger differences between instruments were found with younger age. Standard error of measurement with the Tono-Pen was 1.44 mm Hg and 1.82 mm Hg for the office and anesthesia settings, respectively. Thicker corneas were associated with higher IOP with both the GAT and the Tono-Pen.

CONCLUSIONS In normal children, average differences between IOP measured by Tono-Pen and GAT were small, although there was substantial test-retest variability. Younger age was associated with larger average differences, as was higher IOP in the office setting.