Spotlight ON TECHNOLOGY & TECHNIQUE

Intraoperative Aberrometry Goes Real-Time

By Samantha Stahl, Assistant Editor

Talk to any cataract surgeon about goals, and it's a pretty sure bet that they'll say they strive to avoid enhancement procedures to fix residual refractive error. As patients invest a good chunk of money in a premium procedure, they expect perfection the first time around. Many tools have developed in recent years to increase procedural accuracy, but intraoperative wavefront aberrometry has been an especially intriguing new concept.

Holos IntraOp, a new aberrometer currently in development by Clarity Medical Systems, looks to raise the bar by offering real-time intraoperative wavefront scanning. Real-time data acquisition and display of refractive results are accompanied by simultaneously recorded video.

Need for Speed

With Holos, “the surgeon receives instantaneous refractive feedback based on surgical interventions–i.e., a wavefront refractive ‘movie’ versus still images captured at a point in time,” explains Barry Linder, MD, chief medical officer for Clarity Medical Systems. Surgeons can confirm that a target refraction has been achieved during surgery.

Dr. Linder draws an analogy to pulse oximetry monitoring, which offers real-time acquisition and data display, versus a blood gas measurement's single point in time data capture, with results available after the fact.

He argues that real-time data is critical for a variety of applications that involve dynamically changing refractions, including limbal relaxing incisions or proper axial positioning of a toric IOL to neutralize astigmatism, and also accurate centration of a multifocal IOL in the capsular bag.

Another major advantage: speed.

“Due to the real-time nature of the data acquisition and display, the device does not add procedure time,” Dr. Linder says. “Early clinical investigators have said that in fact, overall procedure time may be saved since the preoperative measurements and corneal marking of the axis may not be required.”

He notes that high data acquisition rate also “reduces any potential blurring of data due to the eye's movement or change in refraction, thereby producing accurate and reproducible data.”

The system's technology will be especially useful for cataract surgery in post-LASIK patients, in whom IOL formulas tend to be less accurate, as well as the aforementioned patients having astigmatic correction with either toric lenses or limbal relaxing incisions, according to Dr. Linder. He also points out the high reproducibility of measurements and control and flexibility in selecting the region of interest and resolution. The device also uses a compact, ergonomic footprint when connected to the operating microscope.

Striving for Perfection

“We're always trying to tighten our accuracy in obtaining emmetropia and orienting toric lenses. In my practice, we obtain 90% of patients within one half diopter of targeted emmetropia and I'm still not satisfied, even though the national average is stated to be about 50%,” says Robert Osher, MD, of Cincinnati. Despite various new surgical techniques, he feels that his practice “just can't nail it in every case,” but having an intraoperative scanning wavefront aberrometer like the Holos device would likely improve our outcomes.

The Holos IntraOp provides real-time intraoperative wavefront scanning.

“It would be great to confirm the refractive error on the table for our standard lenses, and in particular our multifocal and toric lenses. This is a real-time system with immediate feedback, which could be a tremendous asset to the surgeon in contrast to a static system,” he says. In his astigmatism patients, Dr. Osher is especially interested in more accurate IOL alignment since each degree of inaccuracy reduces the astigmatic correction by 3.3%. Studies in both Europe and his own practice show that it is common to miss by five degrees in alignment with the current technology, Dr. Osher explains. He looks to Holos to fulfill two existing challenges: to confirm emmetropia on the table and to more accurately correct astigmatism by precise toric lens alignment.

Pricing plans and a definitive release date are still to be determined, but there is substantial enthusiasm building among the developers and others in the know. Dr. Osher says that the surgeons with whom he has discussed Holos are in agreement that “If the technology bears fruit and proves reliable, we will have a very powerful new weapon in refractive cataract surgery.” OM

For more information, email rhunt@claritymsi.com.