A comparison of four methods of tonometry: method agreement and interobserver variability.
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There was good interobserver agreement with the GAT and moderate agreement between the NCT and GAT, which probably preclude the OBF and Tono-Pen from routine clinical use as objective methods to measure IOP in normal adult eyes.Abstract:
Aim: To compare the inter-method agreement in intraocular pressure (IOP) measurements made with four different tonometric methods. Methods: IOP was measured with the Goldmann applanation tonometer (GAT), Tono-Pen XL, ocular blood flow tonograph (OBF), and Canon TX-10 non-contact tonometer (NCT) in a randomised order in one eye of each of 105 patients with ocular hypertension or glaucoma. Three measurements were made with each method, and by each of two independent GAT observers. GAT interobserver and tonometer inter-method agreement was assessed by the Bland-Altman method. The outcome measures were 95% limits of agreement for IOP measurements between GAT observers and between tonometric methods, and 95% confidence intervals for intra-session repeated measurements. Results: The mean differences (bias) in IOP measurements were 0.4 mm Hg between GAT observers, and 0.6 mm Hg, 0.1 mm Hg, and 0.7 mm Hg between GAT and Tono-Pen, OBF, and NCT, respectively. The 95% limits of agreement were smallest (bias ±2.6 mm Hg) between GAT observers, and larger for agreement between the GAT and the Tono-Pen, OBF, and NCT (bias ±6.7, ±5.5, and ±4.8 mm Hg, respectively). The OBF and NCT significantly underestimated GAT measurements at lower IOP and overestimated these at higher IOP. The repeatability coefficients for intra-session repeated measurement for each method were ±2.2 mm Hg and ±2.5 mm Hg for the GAT, ±4.3 mm Hg for the Tono-Pen, ±3.7 mm Hg for the OBF, and ±3.2 mm Hg for the NCT. Conclusions: There was good interobserver agreement with the GAT and moderate agreement between the NCT and GAT. The differences between the GAT and OBF and between the GAT and Tono-Pen probably preclude the OBF and Tono-Pen from routine clinical use as objective methods to measure IOP in normal adult eyes.read more
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TL;DR: Baseline age, vertical and horizontal cup-disc ratio, pattern standard deviation, and intraocular pressure were good predictors for the onset of POAG in the OHTS and central corneal thickness was found to be a powerful predictor for the development ofPOAG.
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Ocular hypertension treatment study: Baseline factors that predict the onset of primary open-angle glaucoma
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Journal ArticleDOI
Comparison of the Tono-Pen to the Goldmann Applanation Tonometer
TL;DR: It is concluded that the Tono-Pen measures intraocular pressure in a manner that corresponds well to the Goldmann tonometer in the 11 to 20 mm Hg interval, and fairly well in the 4 to 10 mm HG and 21 to 30mm Hg intervals, although it lacks good correspondence in the 31 to 45 mm H g interval.