EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/153099
August 2013 Diagnostic technologies for February 2011 cataract surgery the steep axis prior to surgery. Then, after phaco, he used ORA to measure the aphakic refraction. Dr. Cionni also used ORA for pseudophakic measurements and to confirm the correct position of the lens implantation. In 55% of the eyes studied, or 36 cases, ORA recommended a cylinder power change, Dr. Cionni said. It recommended a power decrease in 27 cases and an increase in nine cases. The average cylinder reduction was 84%. Dr. Cionni concluded that the ORA improved results with the toric IOLs. Moving to the next aberrometric level Image from the new VerifEye hardware upgrade to the ORA aberrometry system Source: Sydney L. Tyson, MD Congress in San Francisco demonstrated exactly how intraoperative aberrometry helps. Robert J. Cionni, MD, medical director, The Eye Institute of Utah, and adjunct clinical professor, John A. Moran Eye Center, University of Utah, Salt Lake City, said he was already getting good results with his aberrometer for toric IOL patients, but he still some- times encountered refractive surprises. That led him to give the topic some further investigation. The study he presented included 65 eyes scheduled for cataract surgery with toric IOL implantation. All eyes had at least 1.5 D of keratometric astigmatism. He used a standard toric IOL nomogram to select the initial cylinder power and marked Improving patient centration and cooperation with aberrometry Intraoperative aberrometry has a learning curve, Dr. Cionni said. One challenge that surgeons have to learn to properly manage is patient centration and cooperation. To help with this, Drs. Cionni and Tyson shared a few pearls: • Make sure the IOP is between 20 and 30 mm Hg. • Keep the corneal surface moist, and make sure that incisions are not leaking. "Some surgeons like to use a cohesive viscoelastic, and some like to use balanced salt solution. I like to use balanced salt solution because it's more physiologic," Dr. Cionni said. • Don't overhydrate your incision as it could give you false readings. • To keep patients looking in the right direction, Dr. Cionni places both hands on their head to stabilize them and asks them to look at the small red light and tell him when it disappears. "If they say at the end it's gone, I know they've been looking at it," he said. • Work with anesthesiology to tell them what you're doing, so the patient will not receive a high dose of sedation just prior to an acquisition. • Expect more challenging work with eyes that have a large number of higher-order aberrations or eyes with keratoconus or post-radial keratotomy. The ORA is undergoing a hardware update called VerifEye that surgeons believe will further strengthen what it can offer in the OR. VerifEye can provide real-time feedback about the patient's refractive state. "This is in contrast to the previous system, which captured a series of physiciancommanded static measurements to assess the refractive state of the eye," said Dr. Fisher, who tested out VerifEye. It also helps surgeons monitor the effect of toric IOL lens rotation and the effect of limbal relaxing incisions as they are created, he added. Dr. Tyson has also tested VerifEye. "Prior to VerifEye, it wasn't as easy to determine when that eye was stable enough to get an acquisition. The lid speculum, ocular surface, and IOP could affect it," he said. Dr. Tyson believes the VerifEye hardware update is a timesaver that will lead to improved outcomes. "VerifEye incorporates a new processor that allows for faster and more accurate results," Dr. Fisher said. Dr. Cionni said his experience with VerifEye anecdotally shows that 94% of patients are within a half diopter of their target spherical refraction. "Those are truly LASIKlike results," he said. Eyeing the Holos wavefront aberrometer Another wavefront aberrometer under development is the Holos (Clarity Medical Systems, Pleasanton, Calif.), Dr. Chang said. Dr. Chang has been involved in developing the first clinical prototypes, EW FEATURE 39 and the first marketable models are expected later this year. "What is exciting about the Holos technology is that it's an entirely new method of performing wavefront aberrometry," he said. "Traditional wavefront applications in ophthalmology have been based either on Hartmann-Shack or TalbotMoire technology. Clarity essentially came up with a different streamlined technology to measure and calculate the wavefront in a much shorter amount of time. As a result, the operating surgeon can look at a display screen in the OR at any given moment and see the actual refraction instantaneously and continuously in real time." Dr. Chang likens the Holos aberrometry technology to watching a video instead of looking at snapshots. "For example, you will have a quantitative (numerical refraction) and qualitative (linear indicator of cylindrical amount and axis) display that you can monitor immediately before and after you make an incision. With a toric IOL, you can rotate the lens and instantaneously see the refraction in real time. The qualitative display will permit us to dial the IOL right into the optimal position," he said. Dr. Chang sees this technology as potentially eliminating the need to mark the eye for toric IOLs— something that surgeons who have used VerifEye also noted. "We would use preoperative keratometry and topography to decide with the patient if astigmatism correction is needed or desired. Then we would use intraoperative aberrometry to confirm the amount of toric correction and the axis at which to orient the IOL," he said. EW Editors' note: Dr. Chang has financial interests with Clarity and Calhoun Vision. Drs. Cionni and Tyson have financial interests with WaveTec. Drs. Cionni and Fisher have financial interests with Alcon (Fort Worth, Texas). Contact information Chang: 650-948-9123, dceye@earthlink.net Cionni: 801-263-5732, rcionni@theeyeinstitute.com Fisher: 850-784-3937, bfisher@eyecarenow.com Tyson: 856-691-8188, sydtyson@comcast.net