Glaucoma is the second leading cause of blindness worldwide. Quigley and Broman (2006) estimated that by 2020, 1,618,718 individuals in the Middle East would have glaucoma; the corresponding estimate for 2020 is 2,295,407 individuals. The intraocular pressure (IOP) measurement is vital for monitoring the effectiveness of treatment and evaluating the risk of glaucoma progression. Since IOP reduction is the objective of treatment, accurate IOP assessment is essential for monitoring the efficacy of therapy and for assessing the risk of glaucomatous progression.
The Goldmann applanation tonometer (GAT) has been considered the gold standard for measuring IOP for a number of decades . However, GAT measurement of IOP is associated with calibration errors, contamination, and certain corneal features, such as central corneal thickness (CCT), corneal curvature, and axial length. Recently, advances in technology, including the dynamic contour tonometer (DCT; PASCAL, Ziemer Ophthalmic System, Port, Switzerland), ocular response analyser (ORA; Reichert Ophthalmic Instruments, Buffalo, NY, USA), and Auto Kerato-Refracto-Tonometer (TRK-1P); Topcon Corporation, Tokyo, Japan), have led to the introduction of several instruments to increase the accuracy of IOP measurements and reduce the risk of infection. However, it is unclear which of these instruments is best for precise measurement of IOP.