Eyeworld

JUN 2012

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

Issue link: https://digital.eyeworld.org/i/78708

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48 EW SECONDARY FEATURE February 2011 Astigmatism June 2012 Tools for aligning toric IOLs by Faith A. Hayden EyeWorld Staff Writer The ORA interoperative aberrometer Source: Mark Packer, M.D. E very cataract surgeon knows that accurate posi- tioning of toric IOLs is essential to optimally correct astigmatism and give a patient the best vision possi- ble. 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, M.D., Vienna, Austria. "Then we've had to use some kind of mark- ing ring in the operating theater to find the steep meridian and try to adjust the lens to that very merid- ian. 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.), the iTrace/Zaldivar Toric Caliper (Tracey Technologies, Hous- ton), Callisto Eye and Z Align (Carl Zeiss Meditec, Jena, Germany), SMI Surgery Guidance (SensoMotoric Instruments, Germany), and Holos (Clarity Medical Systems, Pleasan- ton, Calif.)—that streamline the toric IOL workflow. The iTrace/Zaldivar Caliper Source: Tracey Technologies ORA The ORA interoperative aberrometer is the most recent generation of the system formally known as ORange, said Shamik Bafna, M.D., Cleve- land Eye Clinic, Cleveland. Al- though 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." The ORA isn't without draw- backs. 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, re- sults 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 con- sistent. 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 topog- raphy-based display that is part of the iTrace System and was created in conjunction with Roberto Zaldivar, M.D., Mendoza, Argentina. The Zaldivar Caliper can be used to measure the angle difference be- tween the surgical marks and the toric placement axis. The iTrace is five systems in one, providing cataract and refractive surgeons auto-refraction, corneal topography, ray tracing aberrometry, pupillome- try, 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 learning curve, said Dr. Zaldivar, but it is possible for a surgical team to become too comfortable and de- pendent on the tool. Even so, "it's a system that eliminates big amounts of error that most [surgeons] pro- duce even if they don't know they produce it," he said. SMI Surgery Guidance The SMI Surgery Guidance is a three-part system compromised of the Reference Unit, Surgery Pilot, and Microscope Integrated Display. The SMI Surgery Guidance system Source: SensoMotoric Instruments The system supports precise posi- tioning of the incision, limbal relax- ing incisions, centering and sizing of the capsulorhexis, centering of mul- tifocal IOls, and the exact orienta- tion of toric IOLs. The Reference Unit determines the K-values, limbus, and pupil loca- tion of the patients' eye and simulta- neously captures a high-resolution reference image of the eye, pupil center, eye structure, and vessel structure. The Surgery Pilot is a touch-screen computer connected to the microscope camera where the measurements and images taken with the Reference Unit are dis- played. "The measurement data is stored on a USB stick so the transfer of the data from the Reference Unit to the Surgery Pilot is easy," said Chen Weng, clinical marketing man- ager, SensoMotoric Instruments. Before surgery begins, the surgeon chooses the target axis, incision, lens locations, and rhexis location and diameter. After this planning stage is complete, the Microscope Integrated Display provides a tracking overlay. "The system is totally contact and marker free," Ms. Weng. "We don't touch the patient's eye like other systems may. This is real-time tracking with real-time guidance. It optimizes the entire workflow, and we are much more precise than the manual markers." Callisto Eye and Z Align The Callisto Eye and Z Align is a modular platform that works seam- lessly with the OPMI LUMERA 700 surgical microscope (Carl Zeiss Meditec) to help surgeons align toric IOLs, position incisions and LRIs,

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