Newer Intraocular Pressure Measurement Techniques

Abstract

An elevated intraocular pressure (IOP) has been shown to be one of the major risk factors for glaucoma. It is of utmost importance to obtain accurate and precise IOP when dealing with patients with ocular hypertension and glaucoma, especially patients who have undergone ocular surgery. Goldmann applanation tonometer (GAT) was first introduced in the 1950s and is still currently considered as the gold standard to measure IOP. Although the reproducibility of GAT has shown to be quite good, its accuracy provides several limitations. In particular, IOP measurements taken with GAT have been demonstrated to be influenced by many corneal parameters, including central thickness, curvature, astigmatism and biomechanics. Other disadvantages of GAT include the need for local anesthetic drops, for fluorescein and for a slitlamp. Several different methods have been proposed to overcome the disadvantages found in GAT. The newer devices used as alternative tonometric methods include the iCare rebound tonometer, the BioResonator applanation resonance tonometer, the Pascal dynamic contour tonometer, the ocular response analyzer, the Corvis ST pachy-tonometer and Ocuton S. The precision and accuracy of these alternative tonometric methods in comparison with GAT have been reported and discussed.