EyeWorld Asia-Pacific September 2012 Issue

33 EWAP rEfrActivE September 2012 The ORA intraoperative aberrometer Source: Mark Packer, MD The iTrace/Zaldivar Caliper Source:Tracey Technologies A look at the various systems available or under development to achieve the exact alignment essential to optimizing visual outcomes E very cataract surgeon knows that accurate positioning of toric IOLs is essential to optimally correct astigmatism and give a patient the best vision possible. Exact alignment depends on a host of often-undependable factors such as proper pre-op measurements and axis marking. “Until now, we’ve had to mark the eye before surgery,” said Oliver Findl, MD, Vienna, Austria. “Then we’ve had to use some kind of marking ring in the operating theater to find the steep meridian and try to adjust the lens to that very meridian. In the heat of the moment these things are sometimes forgotten. The patient is lying on the table, already draped, and you suddenly recognize there is no marking. “We know eyes can rotate when [a patient goes] from the sitting to lying position,” he continued. “This is variable from patient to patient so it really is quite important and mandatory to mark beforehand.” Thanks to tools for aligning toric IOLs, this cumbersome and inaccurate manual marking system may soon be ancient history. A number of systems are available or under development—including the ORA (WaveTec Vision, Aliso Viejo, Calif., USA), the iTrace/ Zaldivar Toric Caliper (Tracey Technologies, Houston, Texas, USA), Callisto Eye and Z Align (Carl Zeiss Meditec, Jena, Germany), SMI Surgery Guidance (SensoMotoric Instruments, Germany), and Holos (Clarity Medical Systems, Pleasanton, Calif., USA)—that streamline the toric IOL workflow. OrA The ORA interoperative aberrometer is the most recent generation of the system formally known as ORange, said Shamik Bafna, MD, Cleveland Eye Clinic, Cleveland, Ohio, USA. Although they may look identical, 70-75% of the inner workings of the ORA have been completely changed from the ORange, making the ORA system more accurate and consistent than its predecessor. One big difference is the light source that’s emitted, said Dr. Bafna. “In ORA, they use something called a super LED,” he said. “We’ve found that the new light source allows us to obtain and refine more precise results.” The other distinction is the aspheric lenses the ORA uses, which “help optimize things,” Dr. Bafna said. “There are other things making it easier for the surgeon in terms of aligning the eye before he starts capturing images. It’s a more user-friendly device than what the Orange was overall.” Tools for aligning toric IOLs by faith A. Hayden EyeWorld Staff Writer The ORA isn’t without drawbacks. As with any diagnostic tool, surgeons need cooperation from the patient to be able to look at the right location. Furthermore, if pressure within the eye isn’t consistent, results are inaccurate. “At this point, I go to plan B probably less than 2% of the time. It’s not really a factor,” Dr. Bafna said. “When the ORange was out initially, there were more variables the surgeon had to control. Many times surgeons became frustrated because the results were not as consistent. With the ORA, [Wavetec] has been able to reduce those variables, which has reduced the learning curve for the user.” itrace/Zaldivar caliper The Zaldivar Toric Caliper is a topography-based display that is part of the iTrace System and was created in conjunction with Roberto Zaldivar, MD, Mendoza, Argentina. The Zaldivar Caliper can be used to measure the angle difference between the surgical marks and the toric placement axis. The iTrace is five systems in one, providing cataract and refractive surgeons with auto- refraction, corneal topography, ray- tracing aberrometry, pupillometry, and auto-keratometry. With the Zaldivar Caliper the placement axis can be adjusted at any time based on the surgeon’s review of the corneal topography. “You put two marks in any place on the eye, and simultaneously it takes a measurement of the eye and tells you from this measurement what the steepest axis is,” Dr. Zaldivar said. “Because you have in the same image the mark and the steepest axis, you can calculate what the difference is between the mark and the steepest axis for one side of the eye, for example temporal, and the same for the nasal side.” The caliper doesn’t have a steep continued on page 35