Intraoperative aberrometry can prove its worth
The technology can help take the guesswork out of complicated IOL implantation.
By Lisa B. Samalonis, Contributing Editor
Intraoperative aberrometry can remove some of the guesswork of more complex cataract surgery cases, according to David F. Chang, MD, clinical professor at the University of California, San Francisco.
“Many times, our preoperative calculations leave us uncertain about which of two toric or spherical IOL powers to select,” he says. “For these situations, intraoperative aberrometry can serve as the tie-breaker.”
Dr. Chang notes that clinical studies tend to look at mean refractive errors, but in practice, cataract surgeons are trying to tighten their standard deviation by avoiding the 0.75 D (or more) surprise. This is important because of the lofty patient expectations that accompany use of refractive IOLs, says Dr. Chang, who is also in private practice in Los Altos, Calif.
This article explores how cataract surgeons have used intraoperative wavefront aberrometry to fine tune outcomes in challenging cataract cases.
THE TECHNOLOGY
The WaveTec ORA
Intraoperative aberrometry systems provide real-time data to surgeons during cataract surgery. The ORA System with VerifEye from WaveTec Vision (Aliso Viejo, Calif.) provides continuous streaming refractive assessment of the patient’s eye, allowing for more precise measurements, and refined IOL power recommendations with unique algorithms for standard eyes and the difficult post-refractive eyes.
The system’s pseudophakic measurements give surgeons accurate information on rotating toric IOLs to the proper axis and to assess the effect of limbal relaxing incisions (LRI) during surgery.
The two intraoperative aberrometry systems: the Holos IntraOp (left) that is still awaiting FDA approval; and the ORA System with VerifEye by WaveTec Vision.
ORA VerifEye attaches to the operating microscope and obtains aphakic refractions to calculate IOL power and determine sphere, cylinder and axis. “While the literature shows that 60% to 75% of cataract cases end up within 0.50 D of the formula predicted postoperative spherical equivalent, surgeons using ORA are achieving this goal 85% of the time in their Premium IOL cases. Some ORA surgeons are achieving this 93% of the time,” says Michael Breen, OD, vice president of clinical affairs with WaveTec.
The ORA System is presently the only commercially available intraoperative aberrometer for cataract surgery, and has been used in more than 150,000 procedures to date, according to WaveTec.
The Holos IntraOp
Another system, Holos IntraOp from Clarity Medical Systems Inc. (Pleasanton, Calif.), is in development and a product launch date has not been announced. The sequential scanning wavefront aberrometer, which attaches to the operating microscope, enables rapid data acquisition and real-time data display with highly accurate wavefront refractive measurements (sphere, cylinder, and axis) throughout the surgery.1
“This technology is a fundamental departure from how other devices detect, measure and display wavefront data,” says Barry J. Linder, MD, MS, chief medical officer of Clarity.
Holos is also capable of sampling selective regions of the wavefront. The company says its wavefront technology allows detailed algorithmic data analyses on a streaming basis, resulting in the ability to apply in-depth metrics. The Holos system, which has moved through alpha and beta prototypes, is being further refined before its commercial release.
“During the last several years of clinical experience, Holo’s continuous real-time streaming data, which Clarity invented, has provided an understanding of the variables involved in the surgical environment that may influence wavefront measurements,” says Dr. Linder.
Clarity’s Scientific Advisory Board members will have access to the product in the near future and will report on their experiences.
HOW INTRAOPERATIVE ABERROMETRY AIDS SURGERY
Continuous real-time data
“Both ORA VerifEye and Clarity’s Holos provide the surgeon with a continuous display of refractive data,” Dr. Chang says. “This is very valuable in allowing us to assess how consistent the refractions are, and how they are affected by a variety of factors, including the lid speculum, ocular surface drying, and patient fixation. I was amazed at how sensitive the intraoperative measurements are to a variety of artifacts, and one has to be extremely careful to avoid basing decisions on misleading data.”
Robert Osher, MD, professor at the University of Cincinnati and medical director emeritus of the Cincinnati Eye Institute, likewise extols the virtues of intraoperative wavefront aberrometry. “I have spent my entire career championing the mission of emmetropia,” he says. “For three and a half decades the dream of confirming emmetropia on the table has been unattainable until now. Intraoperative wavefront aberrometry may be capable of both aligning toric lenses and confirming emmetropia in the operating room.”
Comfort level in the OR
Dr. Chang notes he uses the ORA VerifEye system in the OR. “Compared to earlier iterations, the new system is able to provide streaming refractive data, and the time needed to complete the measurements and calculations has been considerably shortened,” he says.
“Intraoperative wavefront aberrometry provides an additional useful tool for optimizing our outcomes with refractive IOLs and astigmatic keratotomy,” Dr. Chang adds. He notes that he uses wavefront aberrometry as a confirmatory check for multifocal and toric IOL power.
He uses intraoperative aberrometry in other cases to refine toric IOL alignment following implantation, or to confirm the preoperative plan before undertaking manual astigmatic keratotomy, and then to assess the refractive result immediately after surgery.
Preoperatively, Dr. Chang’s staff enters the patient data into the cloud-based system. Intraoperative aberrometry adds only a few minutes to each case and the learning curve is short, he says. “The cost of providing this elective refractive service is bundled into the refractive IOL or astigmatic keratotomy out-of-pocket fee,” he says.
Mitchell Jackson, MD, uses intraoperative aberrometry with patients who receive premium or toric IOLs at his Lake Villa, Ill., practice. In the aphakic mode for power selection, he uses intraoperative aberrometry to “help refine the power of the lens implant.” For patients receiving toric IOLs, he uses the pseudophakic mode for axis refinement.
DIFFICULT OR COMPLEX CASES
Dense cataracts
Intraoperative aberrometry can also be helpful for patients who chose a basic IOL but have dense cataract or dense posterior subcapsular cataract where a biometric reading is difficult to obtain. “In these cases we recommend intraoperative aberrometry because once we remove the cataract we have better odds of being within a reasonable refractive error,” Dr. Jackson says.
In addition to improving precision in IOL selection and placement, intraoperative aberrometry can help patients understand premium IOLs because they understand they are getting an additional service. Dr. Jackson explains the service to patients, as “a laser guided, real-time on-the-OR table reading to help pick the proper lens implant for your eye.”
Billing for intraoperative aberrometry
Intraoperative aberrometry can be tricky from a coding perspective, says Kevin J. Corcoran, COE, CPC, CPMA, FNAO, president of Corcoran Consulting Group in San Bernardino, Calif. The key issues include who bills, when and why.
Mr. Corcoran notes that cataract surgery typically does not include intraoperative wavefront aberrometry. However, surgeons do use intraoperative wavefront aberrometry to address refractive errors in some cases, including patients in whom presbyopia-correcting IOLs or toric IOLs have been implanted, and those who get limbal relaxing incisions for the correction of astigmatism.
“In these cases, intraoperative aberrometry can be billed. Otherwise it should not be billed separately,” Mr. Corcoran says.
To bill, use an advanced beneficiary notice, or ABN, to obtain the patient’s agreement that they will pay the fee for intraoperative aberrometry because Medicare will not, Mr. Corcoran explains.
“Any coding problem disappears when it is realized that intraoperative wavefront intraoperative aberrometry is part of a larger, non-covered service,” he says.
However, it is problematic when the surgeon performs intraoperative wavefront aberrometry for conventional IOLs or for patients who do not have astigmatism.
“The service may be performed, but there is no way to bill it, either to the patient or Medicare,” he says, noting that controversy surrounds this last point. “Some surgeons think that if they do it, they can bill the patient just because they did it. The trouble is there must be a good reason why you are billing the patient,” he says, adding that CMS would consider it part of the cataract procedure and therefore not billable.
A white paper on handling reimbursement for intraoperative wavefront aberrometry is available at tinyurl.com/WavefrontWhitePaper.
Overall, he says intraoperative aberrometry helps with precision and reproducibility. “We are between 93% to 94% within 0.50 D now in most cases,” he says. In post-LASIK patients the number is closer to 97% because of advanced testing and careful measurement and evaluation, including biometric formulas.
Correcting astigmatism
Jonathan Talamo, MD, clinical associate professor at Harvard Medical School who practices in Waltham, Mass., has used intraoperative aberrometry in his refractive cataract surgery cases for three years. He has found it valuable for refractive cataract surgery, especially when correcting astigmatism.
He and his partner Kathryn Hatch, MD, presented their collective experience comparing a consecutive series of toric IOL outcomes with and without aberrometry at the 2013 AAO meeting. They found they were 2.5 times more likely to achieve within 0.50 D of intended cylinder with a toric IOL if they used aberrometry during surgery to help adjust the implant.
“We took two identical groups of patients and found that we got about a 57% reduction in astigmatism in the non-aberrometry group and 75% in the aberrometry group, which was a statistically significant difference,” Dr. Talamo says.
He added they achieved residual astigmatism within 0.50 D of target in 78% of patients in the aberrometry group vs. only 33% in the non-aberrometry group. “The mean residual astigmatism was 0.68 D in the non-aberrometry group and 0.46 D in aberrometry group,” he says. “That was statistically significant as well.”
In addition, they found they changed the amount of cylinder in the toric IOL in 25% of cases. In a third of patients they did one or more adjustments of the lens rotationally once it was in the eye. “We found you don’t always get it right the first time: you may have to adjust the power or position of the IOL. Using intraoperative aberrometry reduces the absolute amount of residual refractive astigmatism and, as a result, it also improves the uncorrected acuity,” Dr. Talamo says.
Post-refractive eyes
One of the most important applications of intraoperative aberrometry is IOL power calculation in post-LASIK eyes, says Dr. Chang, co-author of a recent study2 that compared intraoperative aberrometry with relying solely on preoperative calculations.
The retrospective consecutive cases series included 215 cataract patients with previous myopic LASIK or photorefractive keratectomy. In 246 eyes (215 first eyes/31 second eyes) the authors found that intraoperative wavefront aberrometry achieved the greatest predictive accuracy over other preoperative methods. Sixty-seven percent of eyes were within 0.50 D and 94% were within 1.00 D of the predicted outcome. They concluded that intraoperative aberrometry most accurately predicted IOL power estimation in challenging eyes with prior refractive surgery.
REFERENCES
1. Krueger RR, Shea W, Zhou Y, Osher R, Slade SG, Chang DF. Intraoperative, real-time aberrometry during refractive cataract surgery with a sequentially shifting wavefront device. J Refract Surg. 2013;29:630-635.
2. Ianchulev T, Hoffer KJ, Yoo SH, Chang DF, Breen M, Padrick T, Tran DB. Intraoperative refractive biometry for predicting intraocular lens power calculation after prior myopic refractive surgery. Ophthalmology. 2014;121:56-60.
Case: Intraoperative aberrometry for lens selection
This case of a 61-year-old woman demonstrates how intraoperative wavefront aberrometry during cataract surgery can help refine lens selection.
Three different preoperative measurements show three significantly different readings: IOLMaster measured corneal curvature of 2.48 @ 177; autorefraction measured 1.50 @ 177; and other device measurements were 1.12 @ 171.
The target refraction was plano, and our preoperative plan was to implant a 13.50 D SN6AT3 AcrySof IQ Toric IOL (Alcon, Fort Worth, Texas).
To avoid over correcting astigmatism based on the available data, the surgeon selected a toric IOL that corrected the lowest amount of measured astigmatism (about 1.25 D by corneal topography). In the operating room, intraoperative wavefront aberrometry indicated 2.37 D (Figure 1). The surgeon stayed with his original plan and implanted the T3 lens.
Figure 1
ORA system indicated a more powerful lens would have had a better outcome (Figure 2), and the post-insertion measurement shows residual astigmatism (Figure 3). OM
Figure 2
Figure 3
— Jonathan Talamo, MD
Disclosures | |
David F. Chang, MD, disclosed he is a consultant for Clarity but has no financial interest in WaveTec. | |
Mitchell Jackson, MD, has no relevant conflicts to disclose. | |
Jonathan Talamo, MD, disclosed he is a consultant to WaveTec and serves on its medical advisory board. | |
Robert Osher, MD, disclosed he is a consultant to Clarity Medical. | |
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