Dynamic Contour Tonometry (DCT) compared with Goldmann Applanation Tonometry (GAT) in intraocular pressure measurement in patients with penetrating keratoplasty

Abstract

Purpose: : To compare Dynamic Contour tonometry (DCT) with Goldmann applanation tonometry (GAT) in post-keratoplasty corneas, and to assess the influence of central corneal thickness (CCT), corneal curvature (CC) and time after penetrating keratoplasty (PKP) on IOP measurement.

Methods: : This cross-sectional study included one eye of 53 post-penetrating keratoplasty patients. All subjects underwent GAT and DCT IOP measurements in random order, and CCT, CC and astigmatism evaluation. The Bland-Altman method and multivariate regression analysis were used to assess inter-tonometer agreement and the influence of CCT, and CC on IOP.

Results: : DCT significantly underestimated IOP compared with GAT (GAT minus DCT 6.67 ± 7.47 mmHg (95% C.I. 3.97 - 9.36)). In only 33 of the 53 patients IOP measurements with DCT were reliable whereas it was possible to measure IOP adequately with GAT in 49 of 53 patients. A significant relationship between the realibility of the IOP measurements with DCT and CC, the flattest corneal curvature axis (K1), was found.

Conclusions: : On the contrary to prior studies, DCT underestimated IOP compared with GAT. The low agreement found between GAT and DCT and the difficulties in obtaining IOP measures with DCT suggest lesser reliability than GAT in post-PKP patients.

Keywords: intraocular pressure • cornea: clinical science • cornea: clinical science