Abstract:
The dynamic contour tonometer (DCT, Pascal tonometer)was recently introduced as a new method of intraocular pressuremeasurement, supposedly independent of corneal properties. Inthis study we analysed the correlation of dynamic contour tonometryand Goldmann applanation tonometry (GAT) and investigated theinfluence of central corneal thickness (CCT) and corneal curvature.We also considered preferential patient groups for both methods.
In a prospective study of 100 eyes without glaucoma,intraocular pressure was measured using DCT and GAT, followedby measurements of CCT and corneal curvature.
A clear correlation between DCT and GAT was found (R= 0.693; P = 0.000). DCT generally resulted in higher IOP measurements(median difference + 1.8 mmHg). Unlike DCT, GAT was remarkablyaffected by CCT (Fig.1), but neither method was significantlyinfluenced by corneal curvature (Fig.2). In order to obtainvalid readings, DCT required a more extensive selection of patientsthan GAT.
DCT seems to be a reliable method for IOP measurementwhich, unlike GAT, is not influenced by CCT. In clinical practice,advantages from DCT can be expected for cooperative patients,outpatients, and patients with sufficient bilateral ocular fixation,whereas GAT measurements are more reliable in case of patientswith inadequate cooperation, poor vision or nystagmus.
Keywords: intraocular pressure • cornea: basic science • cornea: clinical science