A New Tonometer—The Corvis ST Tonometer: Clinical Comparison with Noncontact and Goldmann Applanation Tonometers

Abstract

PURPOSE.To compare intraocular pressure (IOP) measurements obtained using the Topocon noncontact tonometer (NCT), the Goldmann applanation tonometer (GAT), and the Corvis ST (CST), a newly developed tonometer with features of visualization and measurement of the corneal deformation response to an air impulse. A secondary objective was to assess the agreement among the devices.METHODS. Fifty-nine participants, including glaucoma patients (36 cases) and control volunteers (23 cases), were enrolled. One eye was selected randomly for further study. IOP measurements were obtained with the CST, NCT, and GAT by two experienced clinicians. IOP values were compared. Intraobserver variability and interobserver variability were assessed by the coefficient of variation and intraclass correlation coefficient. Device agreement was calculated by BlandAltman analysis. RESULTS.Mean IOP for all examined eyes was 18.9 6 5.8 mm Hg for CST, 21.3 6 6.8 mm Hg for NCT, and 20.3 6 5.7 mm Hg for GAT. There was no statistically significant difference in IOP measurements among the tonometers except between the CST and NCT. Correlation analysis showed a high correlation between each pair of devices (all P < 0.001). The CST displayed the best intraobserver variability and interobserver variability. Bland-Altman analysis revealed a bias between CST and GAT, CST and NCT, and GAT and NCT of À1.3, À2.4, and À1.1 mm Hg, with 95% limits of agreement of À6.2 to 3.5 mm Hg, À10.1 to 5.2 mm Hg, and À8.3 to 6.2 mm Hg, respectively.CONCLUSIONS. The CST offers an alternative method for measuring IOP. IOP measurements taken with these devices may not be interchangeable. (Invest Ophthalmol Vis Sci. 2013; 54:659-665)

Air-Puff Tonometry in population research – a comparison with Goldmann tonometer in individuals with suspected ocular hypertension

“…The data obtained indicate that values with TG and TA tonometers can be comparable, although the values obtained with both methods are not identical (18) . Other factors not considered in the comparative analysis of tonometers of the present study, such as refractive errors, do not influence the IOP levels obtained with TA and TG (19) .…”

Characterization of Ocular Biomechanics in Pellucid Marginal Degeneration

“…The Corvis ST is similar to the ORA, which is an NCT system that detects ocular biomechanics, corneal thickness, and intraocular pressure (IOP) information. 20,21 The Corvis ST uses a high-pressure air pulse 22 for applanation of the cornea, with a short film sequence (at 4330 frames per second) obtained within a 100-milliseconds period using an integrated ultra-high-speed Scheimpflug camera.…”

“…The Corvis ST is an NCT-based system that provides information regarding corneal biomechanics, corneal thickness, and IOP 20,21 and is thought to have enormous potential as a research and clinical tool. 15,23 In this study, we focused on ocular biomechanical parameters measured with the ORA and the Corvis ST and used these 2 devices to characterize the biomechanical properties of PMD patients.…”

The influence of intraocular pressure and air jet pressure on corneal contactless tonometry tests

“…The CorVis ST is a more recent noncontact tonometer. Using a system similar to the ORA, CorVis ST allows seeing the reaction of the cornea to an air impulse, and it is able to operate on corneas with IOP ranging between 1 and 60 mmHg (Hong et al, 2013). A high-speed Scheimpflug-camera (4330 frames/s) records the movements of the cornea.…”