Eyeworld

EW GLAUCOMA 74 November 2015 Editors' note: Drs. Kotecha and Vajaranant have no financial interests related to this article. Contact information Kotecha: aachal.kotecha@ucl.ac.uk Vajaranant: thasarat@uic.edu measure corneal hysteresis, pro- viding a corneal-compensated IOP reading (IOPcc). ORA readings are quick—they take only 2–3 seconds—but their repeatability coefficient may appear relatively large if there are signif- icant variations in IOP caused by the ocular pulse. No study has yet compared the ORA to manometry to determine its accuracy. Evidence suggests that the ORA is less affected by corneal thickness than GAT, but some evidence sug- gests that the ORA IOPcc is not com- pletely immune to corneal changes post-refractive surgery, Dr. Kotecha said. She thinks this method is more useful for characterizing changes in corneal biomechanics post-refractive surgery. A third option is rebound tonometry, which may be the most useful of all the available methods for diseased or transplanted corneas. In rebound tonometry, a probe is bounced off the cornea or the sclera and the rate of the probe's deceleration is used to calculate IOP. Rebound tonometry is quick, but readings are affected by corneal thickness, and it requires some skill to hit the same spot on the cornea each time. Two rebound tonometry options are currently available: the ICare transcorneal tonometer (ICare, Vanda, Finland) and the Diaton transpalpebral tonometer (Tonom GmbH, Münster, Germany). Both tonometers are hand-held and require no anesthetic. ICare tonom- eter readings are affected by corneal thickness but less affected by corneal edema, so they may be more useful than other methods in pathologic or transplanted corneas, Dr. Vajaranant said. The Diaton tonometer mea- sures pressure through the eyelid and rebounds against the sclera, making no corneal contact, so this method could be an alternative for keratoprosthesis patients, she added. Will GAT remain the gold standard? Considering that patients now have more options for laser refractive surgery, corneal inlays, and trans- plants, Goldmann tonometry is no longer enough, Dr. Kotecha said. All of these tonometry alternatives have their own relative advantages and disadvantages, but they are not interchangeable. It is unclear wheth- er one will win out over the others, but knowing these options, physi- cians can now choose the method that they feel might be best for each patient's condition. EW Reexamining continued from page 72 EyeWorld Blog Focusing on Refractive • Advances in technology • Refractive advice • Surgical techniques • Ask a question • Post a comment • Recommend a topic Visit: Blog.EyeWorld.org " All of these tonometry alternatives have their own relative advantages and disadvantages, but they are not interchangeable. It is unclear whether one will win out over the others, but knowing these options, physicians can now choose the method that they feel might be best for each patient's condition. "

• Cover
• _GoBack
• _GoBack (1)