Differences in intraocular pressure measurements by tonometer type in children with glaucoma and suspected glaucoma

To compare methods for obtaining intraocular pressure (IOP) measurements in children with glaucoma or suspected glaucoma.

The medical records of children (<18 years) with glaucoma or suspected glaucoma with IOP measured by Goldmann applanation tonometry (GAT) and either pneumotonometry or rebound tonometry at a single institution from March 2018 to August 2024 were reviewed retrospectively. The difference between measurements was recorded for each eye. Correlation and Bland-Altman analysis were used to evaluate the level of agreement between tonometers. A linear mixed effects model identified characteristics associated with IOP differences.

A total of 157 eyes of 89 patients were included. GAT was used in all eyes, pneumotonometry in 79 eyes, and rebound tonometry in 78 eyes. The mean IOP by GAT, pneumotonometry, and rebound tonometry was 17.3 ± 5.5 mm Hg, 18.8 ± 5.5 mm Hg, and 20.4 ± 6.0 mm Hg, respectively. Pneumotonometry and rebound tonometry measured higher than GAT with a mean difference of 1.4 ± 3.2 mm Hg (limits of agreement [LOA]: 7.6 mm Hg, -4.3 mm Hg) and 3.1 ± 3.5 mm Hg (LOA: 10.0 mm Hg, -3.9 mm Hg). Correlations between GAT and both pneumotonometry (R = 0.83, P < 0.0001) and rebound tonometry (R = 0.91, P < 0.0001) were strong. Pneumotonometry was associated with a smaller difference from GAT measurements than rebound tonometry (estimate, -1.54 mm Hg). The difference between measurements from rebound tonometry and GAT was influenced by CCT (estimate, 2.35 mm Hg greater discrepancy per 100 μm [P = 0.004]).

In our study cohort of children with glaucoma and suspected glaucoma, IOP measurements obtained with pneumotonometry and rebound tonometry measured higher than GAT but showed good correlation.