EyeWorld India September 2016 Issue

46 September 2016 EWAP CATARACT/IOL by Liz Hillman EyeWorld Staff Writer Managing astigmatism at the intraoperative stage From LRIs and toric IOLs to intraoperative aberrometry, physicians discuss pearls for the young refractive cataract surgeon A fter the preoperative assessment—evaluating measurements for astigmatism in two or three different ways, ensuring measurements are in agreement, and selecting the plan of action for limbal relaxing incisions (LRIs) or a toric IOL—then it’s time to execute the treatment plan and be prepared to manage any surprises at the intraoperative stage. First comes marking the patient for astigmatic correction ahead of surgery. Mitchell Weikert, MD , associate professor and residency program director, Cullen Eye Institute, Baylor College of Medicine, Houston, said he does a couple of things at this point. He draws a picture of the patient’s eye during the preop exam, noting any landmark blood vessels or iris features to use as reference points in the operating room. In the preoperative holding area, Dr. Weikert said his office has weighted markers to place on the eye, but he noted that some of his colleagues will simply use a pen to mark 0 and 180 degrees as reference points. One pearl Dr. Weikert offered here is to mark patients preoperatively while they’re sitting because the eye can rotate when they lie down. Bryan Lee, MD, JD , Altos Eye Physicians, Los Altos, California, does not mark the patient and instead uses the CALLISTO eye markerless system (Carl Zeiss Meditec, Jena, Germany), which has a camera integrated with the The CALLISTO toric positioning line (blue) is used to help the surgeon position an IOL. Source: Bryan Lee, MD The CALLISTO orientation line (yellow) is used to orient the ORA intraoperative aberrometer. IOLMaster (Carl Zeiss Meditec). “I have found it to be accurate and reliable, and skipping manual marking is also great for patient flow,” Dr. Lee said. Elizabeth Yeu, MD , Norfolk, Virginia, ASCRS Young Eye Surgeons Clinical Committee chair, uses the iris registration capture from the NIDEK OPD- Scan III (NIDEK, Gamagori, Japan) and Cassini (i-Optics, The Hague, the Netherlands) to streamline information into the LENSAR laser system (LENSAR, Orlando, Florida) in order to identify the steep meridian. When she uses the LenSx laser (Alcon, Fort Worth, Texas) for surgery, which can be integrated with the Verion Image Guided System (Alcon), Dr. Yeu creates 12 and 6 o’clock limbal reference marks at the slit lamp as she does not have access to the Verion platform. Dr. Yeu does not use intraoperative aberrometry currently but did while she was at the Cullen Eye Institute. Calling the results fairly positive, particularly for the information intraoperative aberrometry can provide in totality, Dr. Yeu maintains that the best corneal measurements are likely those that are captured preoperatively on a naive cornea, untouched by drops and the pressure changes from a lid speculum. “I reviewed my last 6 months of toric cases leading up to [the ASCRS•ASOA Symposium & Congress], and using my preoperative diagnostics, 94% of my toric cases were within half a diopter of refractive residual astigmatism. The Total Corneal Astigmatism (TCA) information provided through near instantaneous capture with the Cassini has provided great insight into the cornea’s true refractive power and astigmatism. I would love to see how intraoperative aberrometry would compare to that and potentially augment the outcome in my hands because I think that it is a great technology,” Dr. Yeu said. Dr. Lee said that while he uses intraoperative aberrometry to help select the IOL’s spherical power, he does not change an IOL’s toric power based on it. “After putting the IOL in, I use aberrometry to tweak the toric positioning,” he said. “It’s ideal if it confirms everything is correct, but if there is a significant discrepancy, I rely on my preoperative measurements. I also use the aberrometer to help titrate my incisions when performing an LRI.” Dr. Weikert offered several pearls for those using intraoperative aberrometry. He uses ORA (Alcon) to confirm his preoperative measurements, help align the IOL to the optimal position, and as a tiebreaker when continued on page 48