Take-home message: A sophisticated integrated formula for IOL power prediction is the featured capability in upgrades to Clarity Medical Systems’ intraoperative wavefront aberrometer.
Reviewed by Warren Hill, MD
An integrated IOL formula (HOLOS Barrett Intraocular Lens Formula) is the centerpiece of a set of recent upgrades to a wavefront aberrometer (HOLOS IntraOp, Clarity Medical Systems).
IOL power predictions based on this new formula—along with integrated aphakic data acquired during surgery—are expected to enhance the precision and accuracy of IOL power selection and help surgeons to achieve the desired refractive outcomes.
External consultants Graham Barrett, MD, Warren Hill, MD, and Douglas D. Koch, MD, developed the IOL power selection algorithm for the system, a continuous, real-time intraoperative aberrometer.
The technology incorporates elements from the Barrett Universal II and the Barrett Rx formulas. The Barrett Universal II formula provides surgeons a calculated IOL power for desired spherical equivalent and postoperative outcomes using preoperative biometry measurements, whereas the Barrett Rx formula incorporates data from the Barrett Universal II formula, as well as the calculated effective lens position and planned refractive outcome to predict IOL power.
“The Barrett Universal II formula is considered by many to be the most accurate theoretical formula currently available,” said Dr. Hill, medical director of East Valley Ophthalmology in Mesa, AZ, and a consultant to Clarity Medical Systems. “Dr. Barrett has brought to the exercise of HOLOS interactive aberrometry that same skill and understanding to help the algorithm produce outstanding results for surgeons.
“It’s one thing to plan, but another thing to know,” Dr. Hill said.
He explained that while surgeons generally presume their preoperative measurements are correct, by using intraoperative aberrometry they have the ability to confirm the measurement or make adjustments in order to better achieve the plaaanned objective.
The ±0.50 D accuracy for most physicians using standard formulas for IOL power and standard technology is about 78%, Dr. Hill said, whereas the accuracy with the HOLOS system is significantly better.
“It will take those physicians who are at 78% and easily move them into mid-80% and possibly approaching 90% for a ±0.50 D accuracy,” he said. “It’s a chance for them to do much better.”
The new HOLOS Barrett formula incorporates intraoperative aphakic measurements to provide an enhanced accuracy prediction of IOL power requirements, said Barry J. Linder, MD, chief medical officer, Clarity Medical Systems.