Purchase this article with an account.
A. Weber, A.G. Boehm, E. Spoerl, L.E. Pillunat; The Effect of Corneal Thickness, Corneal Curvature and Axial Length on IOP Measurements Taken by Pascal Dynamic Contour Tonometry . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4444.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The aim of the study was to examine if there is an influence of central corneal thickness (CCT), corneal curvature and axial length (AL) on Pascal Dynamic Contour Tonometry (DCT) as a method which performs direct, non–invasive and continuous IOP measurements.
In a prospective clinical trial 11 eyes of 11 patients undergoing phacoemulsification (M:F=5:6; mean age 69.4±8.6y), with a corneal thickness of 554.2±29.9µm and a corneal curvature of K1= 43.37 ±1.5D and K2=43.90±2.2D were examined. Before phacoemulsifikation the anterior chamber was canulated at the temporal corneal limbus. In a closed system the IOP was directly set to 15, 20 and 35 mmHg by manometric water column. The different IOP levels were adjusted in a random sequence. IOP was measured by DCT and by intracameral manometry as the gold standard. In addition for statistics DCT readings were compared with Goldmann applanation tonometry (GAT) readings.
At the IOP level of 15mmHg mean differences between intracameral IOP and IOP measured by DCT were 0.1718±1.38mmHg (P=0.69), 0.1638±1.6mmHg at the IOP level of 20mmHg (P=0.743) and 0.7591±2.08mmHg at the level of 35mmHg (P=0.254). There was no correlation between the DCT readings and CCT at all IOP levels: at 15 mmHg (P=0.435), at 20mmHg (P=0.313), at 35mmHg (P=0.078) and also no correlation between the DCT readings and corneal curvature:at 15mmHg (P=0.616), at 20mmHg (P=0.223), at 35mmHg (P=0.188).
From other studies we know that there is an effect of CCT and corneal curvature on applanation tonometry. Therefore, Pascal Dynamic Contour Tonometry: (agreement limits for 15mmHg ±2.8mmHg, for 20mmHg ±3.2mmHg and for 35mmHg ±4.1mmHg) seems to be a good alternative for IOP measurements if corneal thickness or curvature needs to be considered.
This PDF is available to Subscribers Only