Comparison of Dynamic Contour Tonometry with Goldmann Applanation Tonometry

University of Zurich, Zürich, Zurich, Switzerland
Investigative Ophthalmology & Visual Science (Impact Factor: 3.4). 10/2004; 45(9):3118-21. DOI: 10.1167/iovs.04-0018
Source: PubMed


The dynamic contour tonometer (DCT; Pascal tonometer) is a novel tonometer designed to measure intraocular pressure (IOP) independent of corneal properties. The purpose of this study was a comparison of the DCT with the Goldmann applanation tonometer (GAT) with respect to mean of IOP readings, the influence of ocular structural factors on IOP readings, and both intra- and interobserver variability, in a large group of healthy subjects.
In a prospective study of 228 eyes, IOP measurements by GAT and DCT were compared, and the effects of central corneal thickness (CCT), corneal curvature, axial length, and anterior chamber depth were analyzed. To evaluate intra- and interobserver variability, IOP was measured in eight eyes by four observers.
There was a high concordance between the IOP readings obtained by DCT and GAT. However, IOP readings were consistently higher with DCT than with GAT (median difference: +1.7 mm Hg, interquartile range [25th-75th percentile] = 0.8-2.7 mm Hg). In contrast to GAT, multivariable regression analysis showed no significant effect of corneal thickness, corneal curvature, astigmatism, anterior chamber depth, and axial length on DCT readings. For repeated measurements the intraobserver variability was 0.65 mm Hg for the DCT and 1.1 mm Hg for the GAT (P = 0.008). Interobserver variability was 0.44 mm Hg for the DCT and 1.28 mm Hg for the GAT (P = 0.017).
IOP measurements by DCT are highly concordant with IOP readings obtained from GAT but do not vary in CCT and have a lower intra- and interobserver variability. DCT seems to be an appropriate method of tonometry for routine clinical use.

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Available from: Michael A Thiel, Nov 26, 2014
    • "Several studies have demonstrated that Pascal's dynamic contour tonometer (DCT) can be a reasonable alternative for routine IOP evaluation in clinical practice. This conclusion is supported by those studies that have assessed DCT's reliability and by those that have compared it with other tonometers and have estimated the influence of central corneal thickness on DCT's IOP readings[2,3,10,11,141516171819202122. Most of these studies conclude that DCT yields IOP values that are independent from (i.e., not biased by) the subject's CCT and, therefore, that are much closer to the true intraocular pressure. "
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    ABSTRACT: The purpose of this study is to evaluate the concordance between intraocular pressure (IOP) values obtained with a dynamic contour tonometer (DCT) and a non-contact tonometer (NCT) in healthy patients and to investigate the effect of central corneal thickness (CCT) on IOP readings for each of the two measuring systems. The mean IOP yielded by DCT, NCT and corrected non-contact tonometer (CNCT) was 17.1 mmHg, 15.5 mmHg and 12.2 mmHg, respectively. The average CCT was 563.6 μm and the ocular pulse amplitude (OPA) was 2.8 mmHg. There was a moderate correlation between CCT and CNCT (r = 0.34, p = 0.001), a weak correlation between CCT and DCT (r = 0.03 p = 0.788) and a weak-to-moderate correlation between CCT and NCT (r = 0.27, p = 0.11). The intra-class correlation coefficient (ICC) was 0.59 for the DCT-vs.-NCT comparison and 0.56 for DCT-vs.-CNCT. The mean difference between the two instruments (DCT/NCT) ranged from 1.62 to 4.47 mmHg. We have shown that non-contact tonometer is significantly more affected by the central corneal thickness than the dynamic contour tonometer and therefore these methods are not interchangeable.
    No preview · Article · Jan 2016 · Optik - International Journal for Light and Electron Optics
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    • "DCT is a method to measure IOP by using a pressure-sensitive tip that is closely shaped following the corneal curvature to minimize the corneal deformation. The forces of both sides of the cornea are meant to be nearly equal during the measurement.7 DCT measurements have been shown to be independent of structural changes of the cornea such as corneal edema or CCT.4,9–13,20,21 However, some authors describe that DCT is not completely independent from central corneal thickness or corneal edema.14,22–26 "
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    ABSTRACT: Intraocular pressure (IOP) determination using dynamic contour tonometry (DCT) has been considered to be independent of central corneal thickness (CCT), while Goldmann applanation tonometry (GAT) is known to be influenced by various corneal properties. In this study, IOP was measured before and 1 day after cataract surgery using GAT and DCT to investigate the possible effects of corneal edema on IOP measurements. Thirty patients with advanced cataracts were included in a pilot study. IOP was measured using GAT and DCT before and 1 day after phacoemulsification. CCT was determined before and after surgery to quantify postsurgical corneal edema. CCT increased significantly (by 89.7 ± 107.4 μm, P < 0.0001) 1 day after surgery. No significant difference was found for IOP measurements using GAT and DCT before surgery (mean IOP GAT: 17.5 ± 5.7 mmHg; mean IOP DCT: 17.9 ± 6.4 mmHg; P = 0.67) and 1 day after surgery (mean IOP GAT: 16.1 ± 6.6 mmHg; mean IOP DCT: 16.8 ± 8.3 mmHg; P = 0.69). IOP values using GAT and DCT were significantly correlated before as well as 1 day after surgery (before surgery: r = 0.82, P < 0.0001; after surgery r = 0.83, P < 0.0001). Bland-Altman plots showed a high variability in the difference in IOP measurements between methods before and 1 day after surgery. GAT and DCT seem to be equally valuable in IOP determination in postsurgical central corneal edema, although large differences between both methods are present in individual patients. IOP evaluation in corneal edema remains a difficult clinical challenge.
    Full-text · Article · May 2013 · Clinical ophthalmology (Auckland, N.Z.)
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    • "sidered the gold standard of IOP measurement, chiefly, for its relatively low intra-and interobserver variability (Dielemans et al. 1994; Kaufmann et al. 2004). GAT, however, has two major drawbacks compared with rebound tonometer: (i) the use of topical anaesthetic and fluorescein dye, which can cause discomfort to patients and, rarely, allergic reaction (el Harrar et al. 1996; Boezaart et al. 2000); (ii) the use of slit-lamp biomicroscopy , which makes complicates IOP measurement for the handicapped , the elderly and children. "
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    ABSTRACT: Purpose: To evaluate the clinical usefulness of a new rebound tonometer, Icare(®) PRO (Icare PRO), by comparison with Goldmann applanation tonometry (GAT) in a study on patients with glaucoma. Methods: One hundred and seventy-two eyes of 86 subjects were enrolled in this study. All of the subjects were examined with an autorefractometer, Icare PRO, slit-lamp biomicroscope, GAT, ultrasound A-scan and pachymeter. Three intraocular pressure (IOP) measurements were obtained by Icare PRO and GAT. The intraobserver reliabilities were established by calculating the intraclass correlation coefficients. The Bland-Altman plot was used to compare the Icare PRO and GAT. Results: There was a good correlation between the IOP measurement by GAT and that by Icare PRO (r = 0.6995, p < 0.001). The intraclass correlation coefficients of Icare PRO and GAT were 0.778 and 0.955, respectively. The IOP differences between Icare PRO and GAT (mean: 1.92 mmHg; SD: 3.29 mmHg; 95% limit of agreement: -4.52 to 8.37 mmHg) did not vary over the wide range of central corneal thickness (p = 0.498), age (p = 0.248), axial length (p = 0.277) or spherical equivalent (p = 0.075). Conclusions: Although IOP with Icare PRO was higher than that with GAT, especially at lower GAT IOP value, Icare PRO was found to be a reliable method and showed a good correlation with GAT. The IOP difference between Icare PRO and GAT was not affected by the central corneal thickness, age, axial length or spherical equivalent. Icare PRO can be expected not only to be a good screening tool but also to be a good substitute for GAT.
    Full-text · Article · Mar 2013 · Acta ophthalmologica
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