Abstract
Purpose :
As an easy-to-use handheld device, Tono-Pen (Reichert, Inc, Depew, NY) is frequently used to screen for elevated intraocular pressure (IOP). However, Goldmann Applanation Tonometry (GAT) performed at the slit lamp is considered the gold standard for IOP measurement. This study compares the IOP obtained with Tono-Pen (TP) and Goldmann applanation (GAT) in a large-scale electronic health record (EHR) data to identify discrepant measurements and their risk factors.
Methods :
All encounters from 2013-2022 at a single academic center which included one IOP reading using TP and one with GAT within 90 minutes for the same eye were identified from electronic health records. Patient demographics, glaucoma diagnosis, and central corneal thickness (CCT) were identified. The primary outcome metrics were discrepant measurements between TP and GAT as defined in two methods: Outcome A (normal TP despite elevated GAT measurements), and Outcome B (TP and GAT IOP differences >= 6mmHg). Multivariable logistic regression was used to identify factors associated with different IOP readings obtained by the two methods in the same eye.
Results :
Our cohort consisted of 7062 patients with 7062 eligible TP/GAT IOP measurements. The mean absolute IOP difference of TP minus GAT was -0.06 mmHg (+/- 5.70 mmHg 95% CI). There was high correlation between the two measurements at an r-value of 0.759 (p<0.001). We found that TP overestimated pressures at lower IOP <15.3 mm Hg, and underestimated at higher IOP >15.3 mmHg (Figure). Discrepant measurements (outcome A) accounted for 3.13% (N=221), while outcome B accounted for 5.96% (N=421). For outcomes A and B, patients with thinner CCT had higher odds of discrepant IOP (OR 0.88 per 25µm increase, CI [0.85-0.90]; OR 0.91[0.89 - 0.93] for outcomes A and B, respectively). In addition, the male sex (OR 1.47 [1.12-1.93]; OR 1.26 [1.03-1.54]) was associated with higher odds of discrepant IOP measurements.
Conclusions :
In a real-world academic practice setting, TP and GAT IOP measurements demonstrated close agreement on average, although approximately 3% of measurements showed elevated GAT IOP despite normal TP measurements, and approximately 6% of measurements were six or more mmHg apart. Thinner CCT, and the male sex were associated with higher odds of discrepant IOP measurements.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.