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A sophisticated integrated formula for IOL power prediction is the featured capability in upgrades to Clarity Medical Systems’ intraoperative wavefront aberrometer.
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.
Upgrades to the technology platform, introduced last fall, also include the cloud-based InSight physician portal. During surgery, the portal integrates preoperative biometric information and intraoperative data.
Postoperative results are also entered via the portal, Dr. Linder said.
This makes the database valuable to surgeons not only for obtaining quick access to the results of a procedure but also as a mechanism by which they can identify ways to modify their technique at various steps and further improve their outcomes.
“With time, as the data accrue in the portal, this will allow the IOL team that developed the formula to further optimize the overall formula, as well as algorithmically develop physician factors for each of the surgeons who are putting their postop data into the portal and thereby further enhance their results,” Dr. Linder explained.
Outcomes data should begin to appear in the database within the next few months, and the manufacturer will provide surgeon users the analytical tools to assess their outcomes.
The software update for the aberrometer also includes enhancements to the graphical user interface. The goal was to have the HOLOS aberrometer fit into the cataract surgery workflow, Dr. Linder said.
The system automatically detects when the eye is in the phakic, aphakic, and pseudophakic states so that no interaction with the device by the surgeon or the operating room staff is required.
When it detects high-quality measurements, it automatically begins to calculate the predicted IOL using the HOLOS Barrett Intraocular Lens Formula.
In order to better manage the flow of data available during surgery, the manufacturer has designed a novel data display summarizing each IOL prediction from the formula in the form of a histogram, Dr. Linder said.
“It’s an intuitive and immediate visual representation of an enormous amount of data to give the surgeons confidence in the most common predictions from the IOL formula,” he said.
Another component of the software upgrade addresses astigmatism management.
A toric IOL alignment is provided in the graphical user interface to allow surgeons to identify the correct position of the lens. This is achieved when the user aligns, in real time, the toric IOL with a white line on the screen while simultaneously watching the magnitude of the refractive astigmatism decrease.
For toric IOLs, Dr. Hill said the process represents a net solution, taking into account the toricity and alignment of the lens, the posterior corneal astigmatism, and the anterior cornea.
Warren Hill, MD
Dr. Hill is a consultant to Clarity Medical Systems.