Intraoperative wavefront aberrometer aids refraction, astigmatism

A new measurement modality can help surgeons avoid refractive surprises and enhancements

Jack T. Holladay

An emerging wavefront aberrometry technology offers real-time refractive status and improves astigmatism correction during cataract surgery, according to two surgeons who have used the system. They said intraoperative measurements optimize refractive outcomes of toric IOLs and limbal relaxing incisions.

Surgeons can check refraction and exchange lenses during cataract surgery. Image: Donnenfeld ED

OSN Cornea/External Disease Section Editor Eric D. Donnenfeld, MD, FACS, and OSN Optics Section Editor Jack T. Holladay, MD, MSEE, FACS, discussed the ORange System from Wave- Tec Vision.

“It’s a technology that, once you’ve tried it, it’s very difficult to understand how you really existed without it,” Dr. Donnenfeld said. “It just makes sense to be able to do adjustments on the table and not have to worry about bothering patients with postoperative surgery.”

ORange, named because it is used in the “OR” on a “range” of applications, is an intraoperative wavefront aberrometer that attaches directly to the surgical microscope, connected to a processor and touch screen monitor, according to WaveTec. This system allows physicians to capture wavefront data of the patient’s eye to guide the physician in making adjustments real time to optimize the outcome.

In Dr. Donnenfeld’s experience in more than 100 procedures, the ORange recommended adjustments in 35% to 40% of toric IOL cases and approximately 50% of LRI procedures.

Wavefront measurement

The ORange System uses Talbot Moire technology instead of Shack-Hartmann aberrometry or other wavefront measuring techniques, Dr. Holladay said.

“Basically, this technique is more robust than Shack-Hartmann or Tscherning in terms of its ability to get good measurements, which was a little bit of a problem for us in the past during surgery,” he said.

Talbot Moire technology enables a surgeon to check refraction and exchange the lens if necessary, avoiding the need to perform a lens exchange at a later date. It can also help surgeons reduce or eliminate refractive surprises in patients who have had previous refractive surgery.

“I think that’s one of the biggest advantages that it’s going to have,” Dr. Holladay said.

ORange is easy to use and adds only about 1 minute to each procedure, Dr. Donnenfeld said. However, it requires a few minor adjustments in technique.

“There are some small nuances,” he said. “The patient has to be perpendicular, and they have to follow a red light. But it’s very similar to the results we achieve with Shack-Hartmann aberrometry after the surgery.”

LRIs, toric IOLs

Most cataract surgeons perform the LRI procedure at the beginning of surgery and measure astigmatism at the end of the case using the ORange system in order to determine if additional enhancement is necessary, Dr. Holladay said. The system requires that the eye is inflated to at least 30 mm Hg in order to achieve a measurement that will predict postoperative refractive outcomes, he said.

“The data show that we had a significant reduction down to less than 0.5 D of astigmatism with toric IOLs and/or LRIs,” Dr. Holladay said. “The doctors that have used this have taken the second measurement and the enhancement on the table at the time of the original surgery. That’s very exciting.”

Inserting a toric IOL about 1 hour counterclockwise — about 30° — from the intended axis helps the surgeon double-check the original refraction and astigmatism. The position and power of the toric lens can be combined with the ORange measurement at that axis to give the surgeon the exact number of degrees to rotate the IOL to its optimal position.

“You get a chance to preview what the patient’s refraction is going to be 6 weeks out while you’re still on the table, so you can fine-tune things,” Dr. Holladay said. “Both with your LRIs and toric IOLs, you get to do your incisions and your rotation of the lens to a position that duplicates what you’re going to do in the clinic 6 weeks later.”

The ORange System has also been used for corneal transplants, piggyback IOL insertion and other procedures, Dr. Donnenfeld said.

“It’s something I believe will significantly improve surgical outcomes and will become a very welcome addition to our armamentarium in the OR,” he said. – by Matt Hasson

• Eric D. Donnenfeld, MD, FACS, can be reached at OCLI, 2000 North Village Ave., Rockville Centre, NY 11570; 516-766-2519; fax: 516-766-3714; e-mail: eddoph@aol.com.
• Jack T. Holladay, MD, MSEE, FACS, can be reached at Holladay LASIK Institute, Bellaire Triangle Building, 6802 Mapleridge, Suite 200, Bellaire, TX 77401; fax: 713-668-7336; e-mail: holladay@docholladay.com; Web site: www.docholladay.com.