EyeWorld Asia-Pacific December 2015 Issue

46 EWAP REFRACTIVE December 2015 Markerless IOL alignment technologies potentially prevent errors by Louise Gagnon EyeWorld Contributing Writer Adaptation period to digital technology will be required A utomated technologies such as markerless IOL alignment solutions offer ophthalmologists the opportunity to decrease the potential for errors in toric IOL placement in patients undergoing cataract surgery, said Ike Ahmed, MD , assistant professor, University of Toronto, and clinical assistant professor, University of Utah. “Hitting the refractive mark is a multifactorial process,” Dr. Ahmed said. “Accurate biometry is important, IOL calculations and selections are as well, and image- guided surgery may be one of the pieces of the puzzle.” Currently, ophthalmologists manually place markings in the IOL surgical process, but the manual method leaves more room for errors than a digital approach, Dr. Ahmed said. The appeal of an automated, computer-guided system is that it reduces the potential for miscalculations on the part of the operator, and it bridges the office and clinic to the surgical space, Dr. Ahmed explained. The software guides placement of the IOL to ensure accurate orientation and refractive precision. “One of our biggest considerations is errors and the accurate transmission of data,” he said. The computer-guided systems use various fields and dropdown menus where data are entered, saved, and stored on a USB key. That device is then brought to the surgical unit where the data is retrieved. Some devices are able to connect via LAN or a cloud-based system. “Having the transmission of data be automated addresses that concern [about errors]. We think of the surgical environment as our sacred environment, but it is isolated from the office and the clinic. There is little communication between these nodes.” It is vital that there be accurate axis alignment of the IOL for success in toric lens implantation, Dr. Ahmed said. Importing data from the office into the operating room and to the microscope using markerless IOL technologies is an adaptation process for ophthalmologists because it modifies the current workflow. Dr. Ahmed discussed the benefits of two systems that offer markerless IOL alignment: the Callisto Eye (Carl Zeiss Meditec, Jena, Germany) and the Verion Image Guided System (Alcon, Fort Worth, Texas). The Zeiss suite facilitates the transfer of biometry data between the IOLMaster 500 or 700 in the ophthalmologist’s office and the digital system in the operating room, Dr. Ahmed said. “These are attempts to avoid marker solutions and have a markerless system,” Dr. Ahmed said. “We are not used to having overlays on top of our microscopes, but you can think of it like having a heads- Views from Asia-Pacific Cesar Ramon G. ESPIRITU, MD Chairman, Department of Ophthalmology Manila Doctors Hospital United Nations Avenue, Ermita, Metro Manila, Philippines Tel. no. +63-2-5252260 Fax no. +63-2-5243011 local 4080 Espiritueyemd@me.com M arkerless IOL alignment technologies address two major sources of errors in the surgical management of astigmatism. The first, and the less important of the two, is the uncommon possibility of a mistake in the assignment of corrections between different eyes in a surgical list. The efficient, automated transmission of data from the clinic to the operating suite, replacing the old practice of bringing hard copies of patients’ charts and surgical plans, practically eliminates implanting the wrong IOL. The more important (and common) cause of unacceptable post-surgical refractive residual is the incorrect placement of a toric IOL. By accurately digitally marking the eye to negate cyclorotation and other micromovements during surgery, plus guiding the surgeon in the proper positioning of the IOL, it is expected that the correction of preoperatively measured astigmatic error would have a higher degree of success compared to the manual method. What the current systems fail to address, however, is the determination of the true preop astigmatic error which can only be achieved by accurately measuring both the anterior and posterior corneal curvatures and the net axis. I have been using two technologies which are the Verion Image Guided System (Alcon) and the Callisto Eye (Carl Zeiss Meditec). Both have their own surgical planners built into the system but neither input posterior corneal curvatures and the resulting shift in axis in their calculations for the appropriate toric power of the IOL and its recommended position. More than the sources of error previously discussed, this is most likely the reason why results still fall short of expectations and, to the exasperation of both surgeon and patient, why postop refractive surprises occur, although both much less than with the manual method. This Achilles heel should be addressed in order to improve results. We will never be able to accurately correct what we can’t accurately measure. Editors’ note: Dr. Espiritu is a consultant for Alcon. up display when you are driving a car. You will know when you need to look up when you are driving a car, but you focus on the task at hand, whether that is driving or the capsulorhexis.” Dr. Ahmed admitted the