As cataract surgeons manage more previous refractive surgery and toric intraocular lens patients, patient expectations for “perfect” outcomes continue to rise. One of the technologies attempting to address these realities has been Wave-Tec Vision’s ORange intraoperative wavefront aberrometer, which lets the surgeon fine-tune spherical and astigmatic lens choices by measuring the refraction when the eye is aphakic and checking the refraction after the new lens is implanted.
WaveTec Vision is currently preparing to replace existing ORange instruments with a new, more advanced version of the instrument known as the Optiwave Refractive Analysis system, or ORA. Here, two surgeons who have had the opportunity to use the new instrument share their insights regarding the differences between the ORange and ORA devices, and discuss how much the upgrade is affecting their outcomes.
Shamik Bafna, MD, director of cornea services at the Cleveland Eye Clinic in Ohio, one of the demo sites for the ORA, has been using the new device for about four months. He notes that the new model includes a number of major changes. “First, the light source is different,” he says. “Where the ORange used a laser light to take the readings, the ORA uses a super luminescent light-emitting diode, or SLED. WaveTec found that this light source produces a much sharper fringe pattern, allowing readings to be more accurate. Second, the company has improved the overall optics by switching to aspheric lenses, which allow the light to be transmitted more accurately.”
Dr. Weinstock says this also seems to be resulting in better outcomes. “We’ve been checking our patients at one day and one week, and they’ve been right on target,” he says. “The ORange was already helping me tremendously, but I think this is going to be an additional step towards increased accuracy and predictability.”
Dr. Bafna adds that in his experience, the ORA is able to measure a greater number of problematic patients than the ORange. “If the system has difficulty taking a measurement, it puts up a red flag, meaning it was unable to capture a reading,” he explains. “I find that with the ORA, I’m seeing that red flag less often.”
Improved User Interface
Dr. Bafna notes that some changes in the ORA will be immediately obvious to the user. “Those changes include what WaveTec is calling the wide field of view capture,” he says. “The ORange system screen only displayed a fringe pattern indicating the quality of the data capture; you didn’t see the eye. With the ORA, the screen also shows the eye while the data is being captured, making it possible to note potential problems. If the eye isn’t centered or the speculum is pushing on the eyeball, which can raise intraocular pressure and alter the data, you can do something about it and avoid an aberrant reading.”
“The ORA’s graphical user interface is much more sophisticated and polished,” observes Dr. Weinstock. “The screen includes a full-field view of the eye, taken with an infrared camera. That’s important because if the cornea dries out or gets mucusy or the chamber collapses, your reading won’t provide usable data. You can’t always pick that up just from seeing the little bull’s-eye reticle. Also, the new video display helps guide your centration and alignment.”
Drs. Bafna and Weinstock note several other changes for the better:
• On-demand reticle. “One big thing we were missing with the ORange was some guidance,” says Dr. Weinstock. “Now they’ve built a reticle into the software. Once you take a reading, you can press a button on the device and a reticle appears in front of one of your eyes through the microscope. You can use the hash marks on the reticle to align a toric lens or place an LRI correctly and make it the right length. The reticle looks like it’s sitting on the eye.”
• Improved algorithms. Dr. Bafna says that when he first got the ORange, he was not happy with it. “The numbers seemed inconsistent,” he says. “However, over time, Wave-Tec improved the algorithms. Today, I’m a big proponent of this technology, and with the ORA, they’ve improved the algorithms even further.”
“As with any biometry device, different formulas work better for different types of eyes,” notes Dr. Weinstock. “Traditionally, we’ve measured axial length and K-values and plugged them into the various formulas. If someone has a really long eye, you might use a Holladay II formula; if some has a short eye you might use a Haigis or SRKT formula. The ORA has its own set of proprietary formulas that it uses to calculate lens power selection for a particular eye, and it weighs the aphakic refraction and a vergence formula, in addition to K-values and axial length. Those proprietary formulas are based on the large amount of data collected from users of the ORange instrument.
“If you have a post-myopic-LASIK eye, for example, you hit a button on the ORA and tell it that; then it will use a slightly different formula to calculate the lens power,” he continues. “Likewise for a hyperopic LASIK eye, or a very long or short eye. And the company continues to refine the formulas and update them as more cases are done.” (According to the company, the software has optimized lens constants for about 95 percent of all IOLs currently in use.)
• One-step data capture. “Using the ORange was a two-step process,” notes Dr. Bafna. “First you had to make sure everything was in focus; then you’d tell the machine to capture the data. The ORA does all of this in one step, which saves time.”
• Help with marketing to patients. According to the company, the ORA comes with a kit that includes access to a user website with tools designed to help practices explain the technology to patients.
Rolling Out Soon
WaveTec plans to upgrade current owners of an ORange device to the ORA by the middle of 2012. The ORA system will cost about $40,000 with a monthly subscription fee of $3,000, allowing for unlimited use. The ORA systems will start shipping after the first of the year.
Dr. Weinstock has received consultation honorariums from WaveTec, but has no financial interest in the company or either instrument. Dr. Bafna has no financial ties to the company or either instrument.