Intraoperative aberrometry changing standard of care for cataract surgery

Intraoperative wavefront aberrometry has raised hopes and concerns in less than 2 years since its launch.

Some surgeons are confident that the technology will transform cataract surgery, enabling increased accuracy in individualizing lens powers and lens choices and consequently decreasing the need for laser enhancements. Others are more skeptical that the added cost of investing in the new technology is a true value to their practice and patients — at least for now.

WaveTec Vision Systems introduced the ORange wavefront aberrometer at the 2009 American Society of Cataract and Refractive Surgery meeting. The novel form of wavefront analysis offered the opportunity to measure a patient’s refraction during surgery, after wounds were introduced, to make the postoperative result more predictable.

ORange, named because it is used in the “OR” on a “range” of applications, attaches to the surgical microscope to allow for real-time measurements of sphere, cylinder and axis. In about 2 minutes, the device analyzes the wavefront data to help surgeons determine aphakic power calculation and neutralize astigmatism. With its high resolution and dynamic refractive range of –5 D to +20 D, ORange can accommodate almost any eye encountered during cataract surgery.

John A. Hovanesian, MD, FACS, emphasizes patient satisfaction as a measure of the value of new technology. Image: Hovanesian JA

ORange user Robert J. Weinstock, MD, director of Cataract and Refractive Services at the Eye Institute of West Florida, said the device’s ability to reduce laser enhancements can benefit patients and surgeons in multiple ways.

“There will be less cost, less risk and less time spent for everybody if we can avoid doing LASIK on patients after cataract surgery,” he said.

Reduced enhancements

After incorporating ORange, the first and only intraoperative wavefront aberrometry system on the market, into his cataract surgery routine, Dr. Weinstock said he has performed a significantly reduced number of enhancements on his patients.

“Until now, we have been relying solely on preoperative information that dictates what we do intraoperatively,” he explained.

Aberrations are often measured using wavefront technologies, such as Shack-Hartmann, that rely on optical and mathematical principles to capture and analyze a wavefront. However, ORange employs Talbot-Moiré interferometry, a novel form of wavefront analysis that can accommodate the range of refractive error observed in aphakic and pseudophakic patients.

Eric D. Donnenfeld

According to Eric D. Donnenfeld, MD, an OSN Cornea/External Disease Board Member, ORange is a “state-of-the-art informational system” for surgeons. He said that measurements taken preoperatively are helpful but are not enough to make the most accurate decisions on lens power and placement.

Even though it is possible to obtain an adequate aphakic refraction, he said that the effective lens position is essential when conducting a complete analysis of the postoperative refractive error.

Dr. Donnenfeld uses ORange to analyze refraction in both the aphakic and pseudophakic state. When the two provide similar information, then he feels more comfortable with the postoperative results. If there is a difference, however, ORange allows surgeons to re-evaluate lens placement and make changes while the patient is still in the operating room.

“In maybe one in 100 cases, we’ll actually exchange the lens to improve outcomes,” Dr. Donnenfeld said. “The bottom line is: We have reduced our enhancement rate from about 40% to about 10%.”

In an article published in the Nov. 10 issue of Ocular Surgery News, Mark Packer, MD, also reported a reduced number of laser enhancements. After 1 year of using ORange as part of the manufacturer’s beta testing, Dr. Packer said his enhancement rate decreased from 18% to 3%.

Valuable in various aspects of surgery

In a subsequent retrospective case-control study, Dr. Packer observed a nearly sixfold reduction in enhancements after using ORange in a small cohort of patients who chose limbal relaxing incisions (LRI) to correct their corneal astigmatism.

Of the 37 patients who were not evaluated by ORange, six required laser enhancements postoperatively, whereas only one of the 30 patients evaluated with ORange measurements required postoperative treatment, the study said. Although not statistically significant, these results verify that the device can be beneficial in more than one aspect of cataract surgery.

P. Dee G. Stephenson, MD, FACS, ABES, FSEE, of Stephenson Eye Associates in Florida, has been impressed with the multifaceted nature of ORange because it allows surgeons to be precise with both astigmatism and IOL power calculations.

“It is rare that one machine can help you with all kinds of things, and ORange can,” she said.

Dr. Stephenson uses ORange on every patient who requires an LRI, as well as those who undergo toric or premium IOL implantation. She has found ORange aberrometry especially useful to reconfirm the power of an implant in patients with unusual corneas, such as those that are too steep or have shorter axial lengths, as well as in LASIK patients who cannot provide their preoperative keratometry readings.

“This is more than just an affirmation. If your results are good, they will be better with ORange,” Dr. Stephenson said.

Surgeons can use the device to obtain refractive measurements at all stages of cataract surgery, which is essential to reduce the number of laser enhancements.

Dr. Weinstock, for example, has added ORange to an extensive preoperative analysis, which includes immersion or A-scan biometry, manual keratometry, manifest refraction, IOLMaster (Carl Zeiss Meditec), Nidek OPD-Scan wavefront aberrometry and Orbscan topography (Bausch + Lomb).

He also uses ORange after cataract removal to determine lens power selection, and after the lens is implanted, he uses ORange to identify any residual astigmatism, thereby avoiding unsatisfactory refractive outcomes.

Robert J. Weinstock

Dr. Weinstock takes ORange measurements to position toric IOLs on the correct axis and to make or extend LRIs in order to get nearer to the correct postoperative refractive state.

“If a patient has a better surgical result and a better visual acuity, they’re obviously going to be happier postoperatively,” he said.

Increased patient satisfaction

According to John A. Hovanesian, MD, FACS, an OSN Cornea/External Disease Board Member, patient satisfaction measures the value of any new surgical technology.

Several years ago, Dr. Hovanesian and his colleagues at Harvard Eye Associates surveyed patients who had received presbyopia-correcting IOLs. All the IOLs resulted in similar rates of satisfaction, but he said the only factor that correlated strongly with patient satisfaction was uncorrected distance visual acuity, which is affected by residual refractive error after surgery.

“There is a spectrum of patient satisfaction that we should always keep in mind,” Dr. Hovanesian said. “We owe it to patients to offer reasonable technology to improve the quality of our results.”

In some cases, however, technological advances do not always trump a surgeon’s diverse clinical experience.

Although ORange can help achieve desired refractive results, Dr. Hovanesian said that surgeons should not always trust devices whose findings may conflict with their “clinical common sense.” Instead, he believes that the data obtained from any machine should be combined with one’s own expertise to deliver the best possible results to patients.

Evolving formulas

According to Dr. Donnenfeld, the data gathered from ORange helps to create a more effective model for lens positioning. He said WaveTec is conducting regression analysis using the previous nomogram to evaluate the results of implantation from first-generation patients, which could increase the accuracy of the present generation of aphakic aberrometry.

As WaveTec continues to refine the nomogram, Dr. Donnenfeld predicted that surgeons will be able to use intraoperative aberrometry more efficiently by applying additional guidelines to lens power selection.

Dr. Donnenfeld is involved in a study that is assessing the use of ORange in patients who have had previous LASIK or PRK surgery — a group from which it is perhaps most difficult to obtain accurate measurements during cataract surgery.

In a separate study, he and his colleagues are investigating outliers, specifically, the high myopes and high hyperopes for whom regression analysis formulas are not as useful as they are for mainstream patients. The investigators are comparing results from ORange analysis with predictions from preoperative IOL formulas.

Dr. Donnenfeld hopes to complete the latter study in about 3 months and intends to present partial results at the 2011 ASCRS meeting.

According to Dr. Stephenson, ORange users regularly contribute to the development of more accurate IOL calculations by inputting their data into the ORange database.

“It is a work in progress,” she said, explaining that when enough information is gathered, the formulas are recalculated, and the outliers are evaluated. These data allow WaveTec to adjust how the readings are interpreted by the machine.

“The more the database is enlarged, the more accurate ORange can continue to be,” she said.

Costs to patients, practices

Dr. Hovanesian said that increased accuracy is an important goal in cataract surgery, but he said physicians have become too comfortable with an outdated standard of care.

“Ophthalmologists are perfectionists,” he said. “Yet we have fallen into a habit of choosing lens powers and implanting lenses for our patients based upon a standard of care, and now we can do better than that.”

A higher standard of care does not come without a price. For example, premium IOL implantation is not covered by Medicare, so patients can choose to pay out of pocket for the service. With a higher price, however, comes higher expectations of postoperative refraction.

In order for practices to grow, Dr. Hovanesian said it is important for surgeons to strive for better refractive outcomes, which includes adopting new technologies such as ORange. However, Dr. Hovanesian is not a current ORange user, and he said that there is a natural resistance from surgeons to take an interest in intraoperative aberrometry.

“Basically, we are buying an insurance policy against needing to do an enhancement. And yet, if I were a patient, I would buy that insurance policy because I would not have to go through another procedure and take all the intended risks,” he said. “So, on reconsideration, there is greater value for these technologies than immediately comes to mind to us as surgeons.”

Dr. Weinstock said he is not worried about the cost of incorporating ORange into his surgical routine, saying that the device is reasonably priced considering the money it can save a practice in the long term.

By reducing enhancement rates, he said ORange not only reduces subsequent costs to the practice, but also increases the chance for referrals. While physician referrals are often sufficient, patients may be more likely to trust a cataract surgeon who has been recommended by someone with a positive first-hand experience.

“Patients are going out there in the community and telling their friends that they are seeing well right away, and that adds tremendous value to the practice,” Dr. Weinstock said.

Because ORange is an extra service not associated with standard cataract surgery, Dr. Weinstock charges patients an out-of-pocket expense to help defray the cost of purchasing the device, as well as the fee associated with using it. He said this extra charge also covers any additional preoperative testing, as well as intraoperative LRIs.

Not all surgeons charge extra for ORange. Dr. Stephenson, for example, said ORange is already incorporated into her toric and premium IOL packages. She charges patients undergoing LRIs the same price, regardless of whether or not they are analyzed by ORange.

While it is up to the surgeon to decide how to bill patients for ORange, both parties should consider the comprehensive benefits of the technology before being immediately discouraged by costs.

Future advancements

With femtosecond laser technology on the rise, cataract surgery has the potential to become even more accurate as the two technologies coalesce, enabling greater precision and increased accuracy in the operating room.

Dr. Stephenson said in an ideal scenario, ORange will be able to attach to femtosecond lasers during LRI procedures, allowing surgeons to get closer to the correct axis and increase their chances of getting the most on-target result.

She added that the information gleaned from ORange readings has untapped potential, meaning surgeons could eventually find new ways to apply the technology to other surgical procedures.

In fact, Dr. Donnenfeld said he has already found practical applications for ORange outside the arena of traditional cataract surgery. He and his colleagues have used the machine after corneal transplantation to evaluate effective lens position, as well as during IOL exchanges to confirm the correct IOL power.

Despite these innovations, Dr. Donnenfeld said he believes future advancements should focus on IOL position in the aphakic setting, which would help surgeons avoid future lens exchanges or laser enhancements.

“I would predict, almost with certainty, that in the very near future we will be doing higher-order aberration analysis on patients in the aphakic state, looking at mostly spherical aberration and then hand-picking the right intraocular lens to correct the pre-existing higher-order aberration,” he said.

According to Dr. Hovanesian, choosing the wrong IOL power nullifies the benefits of any system that increases the accuracy of lens position. However, he echoed Dr. Stephenson’s thoughts that femtosecond lasers will be used to reduce variability during cataract surgery, as predictable outcomes are perhaps the most important aspect of any ocular surgery.

“By controlling our capsulotomy, we’re going to have more predictable forces of capsule healing that modifies the effective lens position,” he said. “It’s going to allow us to craft our surgeon constant for any individual lens with a smaller standard deviation of the attempted vs. the achieved refraction.”

In addition, Dr. Hovanesian said surgeons can look forward to another intraoperative aberrometer that is currently being developed by Clarity Medical Systems. The system, which has not been approved by the U.S. Food and Drug Administration, allows for real-time wavefront mapping to provide a “moving refraction” that can reduce variability even more.

While the device is still in the early stages of testing and development, Dr. Hovanesian said it has the potential to become a meaningful competitor because of its advanced technology.

“It’s definitely a system to keep our eye on,” he said.

Although he has not yet incorporated intraoperative aberrometry into his practice, Dr. Hovanesian said he recognizes the benefits of the technology and offered some advice to surgeons who may be unconvinced of its value.

“We have to stop thinking of intraoperative wavefront as being an overpriced insurance policy and start thinking about it as a pathway toward delivering the result that we are promising with premium IOLs,” Dr. Hovanesian said. – by Courtney Preston and Matt Hasson

To take full advantage of new diagnostic technologies, what steps should IOL manufacturers take to improve IOL power and sizing?

Reference:

• Packer M. Effect of intraoperative aberrometry on the rate of postoperative enhancement: Retrospective study. J Cataract Refract Surg. 2010;36(5):747-755.

• Eric D. Donnenfeld, MD, can be reached at Ophthalmic Consultants of Long Island, 2000 N. Village Ave., Rockville Centre, NY 11570; 516-766-2519; fax: 516-766-3714; e-mail: eddoph@aol.com. Dr. Donnenfeld is a consultant to WaveTec.
• John A. Hovanesian, MD, FACS, can be reached at Harvard Eye Associates, 24401 Calle De La Louisa, Suite 300, Laguna Hills, CA 92653; 949-951-2020; fax: 949-380-7856; e-mail: drhovanesian@harvardeye.com. Dr. Hovanesian has no financial interest in the products mentioned in this article.
• P. Dee G. Stephenson, MD, FACS, ABES, FSEE, can be reached at Stephenson Eye Associates, 200 Palermo Place, Venice, FL 34285; 941-485-1121; e-mail: eyedrdee@aol.com. Dr. Stephenson has no financial interest in the products mentioned in this article.
• Robert J. Weinstock, MD, can be reached at The Eye Institute of West Florida, 148 W. 13th St., SW, Largo, FL 33770; 727-581-8706; fax: 727-586-3743; e-mail: rjweinstock@yahoo.com. Dr. Weinstock is a paid consultant to WaveTec.