EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/422211
EW MEETING REPORTER 70 December 2014 Reporting from the 2014 Asia-Pacific Association of Cataract & Refractive Surgeons annual meeting, Jaipur, India With the RBF model, surgeons will have to input only 3 measured variables—axial length, corneal power, and anterior chamber depth —dropping effective lens position and vergence calculation inputs. Based on several studies of the mod- el's refractive results, RBF formulas have been shown to deliver power calculation accuracy on par with, or better than, the most advanced theoretical models in use today. Half diopter accuracy has consistently been between 92% and 96%, Dr. Hill said, far better than he or his colleagues anticipated. The RBF model will open up a brand new era of IOL power calcu- lation, Dr. Hill said, making tailored IOL selection possible for large population groups with previously ignored anatomical differences. "One of the ironies of all the lens power calculation formulas we've had to date is that they're based on eyes of European ances- try," he said. "Anyone who lives in Hong Kong will tell you that some of the formulas we love in Europe and North America don't work for southern Chinese." The RBF formula will allow surgeons to make IOL calculations more specific and sensitive for the ethnic groups that have ocular anatomical differences such as shorter anterior chambers and longer vitreous cavities. RBF power calculations represent a robust approach based on pattern recognition and data interpolation, Dr. Hill concluded. "When we have this much sensitiv- ity and this much accuracy, we can begin to do things that have not been done before." Dr. Hill gave the first APACRS Lim Lecture since the passing of Prof. Lim, who founded the APACRS and was a renowned ophthalmol- ogist in the Asia-Pacific region and around the world. In an interview with EyeWorld prior to the meeting, Dr. Hill said he was honored to give the APACRS Lim Lecture this year. "It is indeed a great honor to be asked to give such an important lecture dedicated to the father of Southeast Asian Ophthalmology," Dr. Hill said. "Almost singlehand- edly, Prof. Lim transformed our specialty in this region. Leading by example, he became a most be- loved educator, humanitarian, and pioneering surgeon. His passing on August 30 will be mourned by many whose lives and careers he touched." Perfect cut, clarity, prediction The Combined Symposium of Cataract and Refractive Societies (CSCRS) is a unique forum where the major regional societies—the APACRS, the American Society of Cataract & Refractive Surgery (ASCRS), the European Society of Cataract & Refractive Surgeons (ESCRS), and the Latin American Society of Cataract and Refractive Surgeons (ALACCSA-R/LASCRS)— join forces. The first CSCRS was held at the 2005 APACRS annual meet- ing in Beijing, and has since been held at the annual meetings of the involved societies. "For us, it's the highlight of our meeting," said Dr. Barrett, president of APACRS. This year, the CSCRS focused on the various strategies and technol- ogies that allow surgeons to create that "perfect cut" to achieve "perfect clarity" and "perfect prediction." In Dr. Barrett's talk on "Toric IOL Prediction," he focused on ways to optimize outcomes with toric IOLs. Dr. Barrett recommended using three devices to assess every patient: one primary (an optical biometer) and two secondary (a topographer and a manual keratometer). Toric IOLs require that surgeons measure surgically induced astigma- tism (SIA) and axis alignment. When measurements of these parameters are not available, surgeons can base their refractive target calculations on assumptions of one or both. Howev- er, in a study of 54 eyes, Dr. Barrett found that using known (measured) SIA with assumed axis alignment provided substantial improvement over calculating with assumed SIA and assumed axis alignment; measuring both further improved outcomes, but not as substantially. In terms of alignment, Dr. Barrett described the use of the toriCAM app he developed togeth- er with a macro lens and a felt tip pen. The app converts the surgeon's mobile device into a digital marking aid. Exploring digital markers further, Cesar Espiritu, MD, Metro Manila, Philippines, talked about these devices that allow surgeons to place incisions and align toric IOLs "where they should be." Specifically, he described the components of current digital mark- erless systems: an image guidance system that uses conjunctival blood vessels, iris characteristics, white-to- Graham Barrett, MD, and Ronald Yeoh, MD, honor Abhay Vasavada, MD, the recipient of the APACRS Gold Medal and this year's organizing chairman. Supported by