Comparison of dynamic contour tonometry with goldmann applanation tonometry

Area of Science:

• Ophthalmology
• Optometry
• Biomedical Engineering

Background:

• Intraocular pressure (IOP) measurement is crucial for diagnosing and managing glaucoma.
• Traditional tonometers like Goldmann applanation tonometer (GAT) are influenced by corneal properties.
• The dynamic contour tonometer (DCT; Pascal tonometer) is a novel device designed for IOP measurement independent of corneal biomechanics.

Purpose of the Study:

• To compare the dynamic contour tonometer (DCT) with the Goldmann applanation tonometer (GAT).
• To assess the influence of ocular structural factors on IOP readings from both devices.
• To evaluate the intra- and interobserver variability of DCT and GAT in healthy subjects.

Main Methods:

• A prospective study involving 228 eyes.
• Comparison of IOP measurements obtained by GAT and DCT.
• Analysis of the effects of central corneal thickness (CCT), corneal curvature, axial length, and anterior chamber depth on IOP readings.
• Evaluation of intra- and interobserver variability by four observers measuring IOP in eight eyes.

Main Results:

• High concordance was observed between DCT and GAT IOP readings.
• DCT readings were consistently higher than GAT readings (median difference: +1.7 mm Hg).
• Unlike GAT, DCT readings showed no significant influence from CCT, corneal curvature, astigmatism, anterior chamber depth, or axial length.
• DCT exhibited significantly lower intraobserver (0.65 mm Hg vs. 1.1 mm Hg) and interobserver (0.44 mm Hg vs. 1.28 mm Hg) variability compared to GAT.

Conclusions:

• DCT provides IOP measurements highly concordant with GAT but independent of corneal properties.
• DCT demonstrates superiorly low intra- and interobserver variability.
• The DCT is a suitable and reliable method for routine clinical tonometry.