5 It has been shown that central corneal thickness (CCT) in these patients is higher than that in their normal peers.6-9It is now recognized that biomechanical properties of the cornea are also important, in addition to the geometric thickness. The study of CCT and corneal biomechanical characters and their effects on the measured IOP using common tonometers in this particular group may assist in our understanding and management of this unique group of patients. The Goldmann Applanation Tonometer

(GAT) is regarded as the reference standard for checking IOP. However, it is common knowledge that the accuracy Inhibitors,research,lifescience,medical of the device, that is, its ability to provide a measure of the true IOP, is Cabozantinib affected by corneal properties. The Ocular Response Analyzer (ORA, Reichert Ophthalmic Instruments, Inc., Buffalo, New Inhibitors,research,lifescience,medical York, USA) is a noncontact device that analyzes corneal biomechanical properties simply and rapidly. Variables obtained by the ORA are corneal-compensated IOP (IOPcc), Goldmann-correlated IOP (IOPg), corneal hysteresis (CH), and corneal resistance factor (CRF). IOPg corresponds to IOP measured with GAT, and IOPcc is thought to be less affected by corneal properties than GAT. The Tono-Pen Inhibitors,research,lifescience,medical XL (TXL, Reichert Ophthalmic Instruments, Buffalo, USA) is a portable hand-held instrument. It is based

on the Mackay-Marg principle and utilizes micro strain gauge technology. A 1.00 mm transducer tip, covered by a disposable single-use cap, contacts the cornea and displays the average of four independent readings.10 It is known that corneal thickness affects the measured IOP.11 The ORA has been proposed to measure IOP independent of corneal Inhibitors,research,lifescience,medical thickness, and the TXL has been suggested to be less affected by corneal thickness Inhibitors,research,lifescience,medical because of its small area of contact with the cornea while measuring IOP. We sought to determine whether the thick cornea of patients with aphakic glaucoma affects the readings of these tonometers compared to GAT. The primary purpose of our study was to determine the agreement between the measurement of IOP by the TXL (suggested to be less affected by the cornea because of the small area of contact

with the cornea while measuring IOP) and ORA (proposed to measure IOP independent of the corneal characters) with GAT, as a standard tonometer, in a group of aphakic glaucoma children with a CCT greater than 600 µ. Secondary objectives were to determine corneal biomechanical properties enough in this group of patients. Finally, we aimed to find out the effects of CH, CRF, and CCT values on the IOP measurements obtained using the aforementioned tonometers. Patients and Methods This cross-sectional study was conducted after approval from the local Ethics Committee. Informed consent was obtained from the parents of the enrolled children in the study. We used Power SSC program (version 1.00) (Sample Size Calculator and Power Analysis).