EyeWorld Asia-Pacific September 2016 Issue

45 EWAP CATARACT/IOL September 2016 continued on page 52 IOL power, the RBF calculator uses a given set of measurements and a postop refractive target, Dr. Hill said. “This technology is then used to identify a basic underlying pattern combined with a sophisticated form of data interpolation,” he said. “What we currently do when selecting an IOL power is enter our measurements into a theoretical formula and hope for the best. Using the most modern theoretical formulas like Barrett and Olsen, the outcomes are excellent,” Dr. Hill said. However, theoretical formulas are usually based on regression algorithms, and there are always exceptions that can snag the numbers—even if the regression algorithm is particularly sophisticated. “This is because the human eye is like a Chinese puzzle in terms of the enormous number of probable and improbable combinations of axial length, Ks, and anterior chamber depths,” he said. By contrast, the pattern recognition and data interpolation used with the RBF calculator works in a different manner and is fundamentally better suited to keeping track of the complex, nonlinear relationships that define certain aspects of the human eye, Dr. Hill said. Because of this unique approach, the RBF calculator brings something new to surgeons. “The RBF calculator not only suggests the necessary IOL power to achieve the refractive objective, but it also tells the user whether or not an individual calculation is within an internal boundary model,” Dr. Hill said. Boundary models are a commonly used tool in engineering, used to define the limits of accuracy for a specific type of calculation. Tracking outcomes A team of 24 volunteer ophthalmologists in 13 countries from around the globe have gathered patient data and provided feedback on the RBF calculator over the past 6 years, Dr. Hill said. Haag-Streit (Köniz, Switzerland) helped fund work on the RBF calculator. Peter Maloney from MathWorks (Novi, Michigan) guided Dr. Hill and colleagues through model development; current core investigators include Douglas Koch, MD , and Li Wang, MD , Houston; Adi Abulafia, MD , Tel Aviv, Israel, and David Goldblum , Basel, Switzerland. As part of the investigation within cataract surgery, the RBF calculator was retrospectively evaluated by 13 of the project’s surgeons in eight countries. Its use led to a weighted mean accuracy of 95%, which was an enormous improvement on the current mean accuracy of 78%, which is most commonly seen using the most popular theoretical formulas, Dr. Hill reported during the Charles Kelman Lecture at the 2015 American Academy of Ophthalmology annual meeting in Las Vegas. Results from a Haag-Streit study that Dr. Hill presented at the 2016 ASCRS•ASOA Symposium & Congress found that in a multicenter, prospective study of 459 eyes, 91% were within ±0.50 D of the intended target. The axial length of the eyes in this main group ranged from 20.97 mm to 29.10 mm. The calculator reached the ±0.50 D target in 98.4% of patients with axial myopia (n=62; axial length greater than 25 mm) and 84.5% of patients with axial hyperopia (n=58; less than 22.5 axial length). A little more than Double protection, double safety ! Tomography Biomechanics Now, measurable biomechanics – Corvis ® ST ! And for you that means: twice as much information for twice as much safety in pre-op screening for keratorefractive surgery. Enhance your practice with the world’s first tonometer capable of measuring and interpreting the biomechanical properties of the cornea. In combination with the tomography values from the OCULUS Pentacam ® , it gives you maximum safety and efficiency in refractive screening. OCULUS Corvis ® ST – take care of more patients with greater safety ! Want to learn more about corneal biomechanics? Check out www.corneal-biomechanics.de for more information, scientific material and lectures from the experts. OCULUS Asia Ltd. Hong Kong Tel. +852 2987 1050 • Fax +852 2987 1090 www.oculus.de • info@oculus.hk 92% of normal eyes (n=347; axial length 22.5 mm to 25 mm) were within ±0.50 D. In a poster at the Association for Research in Vision and Ophthalmology (ARVO) annual meeting earlier this year, the RBF method also gave excellent