Issues in Custom LASIK: QUALITY OF VISION
What the FDA trial results tell us about progress.
BY DESIREE IFFT, EXECUTIVE EDITOR

On January 30, the Council for Refractive Surgery Quality Assurance (CRSQA) issued an advisory memorandum to all users of wavefront-guided excimer lasers. The memo states in part that it has come to the organization's attention that patients are commonly being told that wavefront-guided excimer lasers are approved by the FDA to treat and correct higher-order aberrations (HOA). It further states that "a review of the relevant documentation will find the FDA approvals do not include language that supports the contention that wavefront-guided excimer lasers are FDA approved to correct HOA."

ILLUSTRATION: JIREH DESIGN

This undoubtedly would come as a surprise to many of the patients who've been reading about wavefront refractive surgery on the Internet for months, even years, and perhaps to some ophthalmologists as well.

The sole purpose of the CRSQA memorandum is to encourage honest, accurate communication between surgeons and their patients. But it also underscores the fact that confusion exists in the marketplace over exactly what the recent wavefront FDA approvals cover and -- more importantly -- what capabilities the procedures have to improve patient quality of vision compared with standard procedures.

In an effort to clarify these issues, this article points to key aspects of the FDA labeling, including the Professional Use Information Manuals, associated with the three platforms approved for wavefront-guided LASIK. It also presents opposing surgeon opinions of what the trial data do or do not show.

Overall, Trial Results Were Excellent

On the key FDA clinical trial criterion of postoperative UCVA at 6 months post-op, all three wavefront-guided platforms achieved results superior to conventional LASIK:

► After treatment with Alcon's CustomCornea, 98.6% of spherical myopia eyes were corrected to 20/40 or better, and 79.9% were corrected to 20/20 or better.

► After treatment with VISX's CustomVue, 100% of spherical myopia eyes were corrected to 20/40 or better, and 95.8% were corrected to 20/20 or better, and among astigmatic myopia eyes, 99.5% were corrected to 20/40 or better, and 93.2% were corrected to 20/20 or better.

► After treatment with Bausch & Lomb's Zyoptix, 99.4% of spherical and astigmatic myopia eyes were corrected to 20/40 or better, and 91.5% were corrected to 20/20 or better.

Comparison of UCVA results is complicated because patient inclusion criteria varied among the FDA studies, but taken as a whole, the outcomes are impressive.

Beyond Visual Acuity

When the analysis moves beyond post-op refraction is when it becomes more difficult to determine if, and why, custom LASIK is superior to standard LASIK. Other quality of vision parameters, such as contrast sensitivity and higher-order aberration levels, come into play. Here is a summary of FDA labeling information, some of which relates specifically to quality of vision:

Approval Range

► Alcon CustomCornea: Myopia up to 7.00D with less than 0.50D of astigmatism at the spectacle plane. (Up to -8.0D of myopia and -1.5D of astigmatism can be treated, as long as the manifest refraction is within a diopter of the wavefront refraction.)

► VISX CustomVue: Myopic astigmatism up to -6.00D MRSE, with cylinder between 0.00 and -3.00D.

► B&L Zyoptix: Myopia with sphere up to -7.00D and cylinder up to -3.00D and MRSE less than or equal to -7.50D at the spectacle plane.

Eyes Evaluated/Follow-Up

► Alcon CustomCornea: Total 426 eyes. Of all eyes treated, 426 were available for analysis of safety at 3 months, and 424 eyes were followed for 6 months. Accountability at 3 and 6 months was 100% (one patient was deceased). Of these eyes, 139 were evaluated for effectiveness with 100% accountability at both 3 and 6 months.

► VISX CustomVue: Total 351 eyes. Of all eyes treated, 318 were evaluated for effectiveness with 98.8% accountability at 3 months, 277 eyes with 96.9% accountability at 6 months, 102 eyes with 95.3% accountability at 9 months, and 86 eyes with 95.6% accountability at 12 months.

► B&L Zyoptix: Total 342 eyes. All treated eyes, 340, were available for analysis of safety at 3 months and 6 months, with all eyes being followed for 6 months. Accountability at 3 and 6 months was 100%. All 340 eyes were evaluated for effectiveness with 100% accountability at both 3 and 6 months.

Contrast Sensitivity

► Alcon CustomCornea: Post-op contrast sensitivity was compared with pre-op contrast sensitivity using the VectorVision CSV 1000. (change of greater than 2 levels (>0.3 log) at 2 or more spatial frequencies for spherical myopic eyes; mesopic illumination with neutral density filters in front of eyes) At 6 months, 2.2% of patients improved on photopic testing and 0.7% were worse. Also at 6 months, 15.2% of patients improved on mesopic testing, and 5.8% were worse.

The Professional Use Information Manual states: "Minor improvements with CustomCornea LASIK were noted in visual acuity and contrast sensitivity relative to conventional LASIK with the LADARVision 4000 system."

► VISX CustomVue: Labeling does not include information about contrast sensitivity.

► B&L Zyoptix: Post-op contrast sensitivity was compared with pre-op contrast sensitivity using the Vision Sciences CST 1500 with FACT charts. (change of greater than 2 levels (>0.3 log) at 2 or more spatial frequencies for spherical myopic eyes) At 6 months, 24.4% of patients improved on photopic testing, 72.1% stayed the same, and 3.5% were worse. At 6 months 22.7% improved on mesopic testing, 75.2% stayed the same, and 2.1% were worse.

Comparison to Standard Treatment/Higher-Order Aberrations (HOA)

► Alcon CustomCornea: Data on 25 patients (50 eyes) was used to compare CustomCornea LASIK to conventional LASIK. Twenty of those patients received CustomCornea LASIK in one eye and coventional LASIK in the other. (Five patients received conventional in both eyes.)

The labeling states that the amount of post-op HOA was less for CustomCornea LASIK eyes than for conventional LASIK eyes. At 6 months, the average increase in HOA was 82% for conventional LASIK eyes and 20% for CustomCornea eyes.

For most patients, CustomCornea LASIK did not reduce HOA from baseline levels prior to surgery. However, the percentage of patients with reduced HOA at 6 months post-op compared with before surgery was 14% for conventional LASIK eyes and 38% for CustomCornea LASIK eyes.

► VISX CustomVue: Labeling states: "Although the WaveScan WaveFront System measures the refractive error and wavefront aberrations of the human eyes, including myopia, hyperopia, astigmatism, coma, spherical aberration, trefoil, and other higher-order aberrations through sixth order, in the clinical study for this PMA, the average higher order aberration did not decrease after CustomVue treatment."

► B&L Zyoptix: Forty patients in the FDA trial underwent conventional LASIK in one eye and Zyoptix LASIK in the other eye. The amount of post-op HOA was less for Zyoptix LASIK eyes than for conventional LASIK eyes. At 6 months, the average increase was 45.3% for conventional LASIK eyes and 13.4% for Zyoptix LASIK eyes.

For most patients, the Zyoptix LASIK did not reduce HOA from baseline. In the 40-patient contralateral study, the percentage of patients with reduced HOA at 6 months post-op compared with before surgery was 12.8% for conventional LASIK eyes and 37.5% for Zyoptix LASIK eyes.

The label also states: "Although the ZyWave Wavefront System measures the refractive error and wavefront aberrations of the human eyes, including myopia, hyperopia, astigmatism, coma, spherical aberration, trefoil, and other higher order aberrations through fifth order, in the clinical study for this PMA, the average higher-order aberration did not decrease after Zyoptix Personalized Vision Correction."

How the Data is Playing in the Real World

It's important to be aware that in the cases where a clinical trial compares standard with custom results, the number of eyes analyzed is small. Also important: None of the three approved platforms decreases preoperative HOA in all patients, which is why none are officially FDA-approved for HOA correction. Submitted data did not show that higher-order aberration correction was predictable or consistent.

What all the wavefront-guided platforms clearly do, however, is induce far less HOA than standard LASIK.

Therein lies their real impact: improvement of overall quality-of-vision, according to Steve Schallhorn, M.D., a refractive surgeon and captain in the U.S. Navy. Dr. Schallhorn leads the Navy's efforts to improve vision quality for pilots and other personnel whose vision is crucial. He has analyzed his own cases as well as raw PMA data from the Alcon and VISX custom trials. "No matter how you crunch the numbers, the quality of vision with wavefront-guided LASIK is slightly but significantly better than with standard," he says. "That doesn't mean everyone will improve. You get results distributions with both custom and standard; some patients improve; some patients stay the same; and some get worse. But the bell curve has shifted toward improvement with custom. I'm convinced that fewer patients, not zero patients, but fewer patients, will have problems like glare, halos and poor night vision."

The levels of improvement are clear in the responses to patient satisfaction questionnaires that were part of all three wavefront-guided LASIK FDA trials. Each trial's surveys were structured differently, but these crucial subjective outcomes were similar. When asked about night vision, for example, across the board, more patients were very satisfied or satisfied post-op compared with pre-op, and fewer were dissatisfied. Most early adopters of custom technology, who have now had time to compile some of their own data, are reporting objective and subjective improvements in their patients. (See "Barriers to Perfection," above.)

Meanwhile, other surgeons are drawing different conclusions and remain unconvinced that custom procedures are superior for the majority of patients. David Wallace, M.D., a Los Angeles refractive surgeon, has performed 9,000 LASIK procedures, only some of which were wavefront-guided. "I can only support custom when there's a clear reason to," he says.

He recommends it (in preference to conventional LASIK) only in specific situations, such as when astigmatic hemimeridians aren't 180 degrees apart, or are 180 degrees apart but of a different magnitude. He also supports its use in cases of asymmetric topography, and when patients volunteer that one eye is subjectively 'weaker' than the other and shows greater HOA on wavefront analysis. "Since July of last year, I have done wavefront analysis as a part of every consultation, but I look for hard clinical benchmarks," he says. "Conventional LASIK is good, and I resent people implying otherwise. Some patients are unhappy with their standard LASIK results. I'm just not sure it's true that the problems are related to higher-order aberrations and that treating them will eliminate the problems."

Dr. Wallace's Web site, www.la-sight.com, he says, offers comprehensive content and does not endeavor to overstate or oversell the advantages of wavefront-guided LASIK. The site's Advanced Laser Optics page lists what he sees as the important issues that need to be addressed, such as the inability of any laser system to compensate for the distortion of the beam as it strikes the cornea. He also says that he has been able to achieve excellent quality-of-vision results without using his laser's pupil tracker just by using a fixation ring. And he says that no matter how precise the laser, creating and repositioning a corneal flap alters the aberration profile. "The point is that wavefront is not the 'magic bullet'," he says.

Not a Magic Bullet, but a Turning Point

Those in the know agree with Dr. Wallace's magic bullet statement. During one of the FDA Ophthalmic Devices Panel meetings, a representative of one of the companies presenting custom LASIK data phrased it this way: "It is true that even after our wavefront-guided surgery, that the higher-order aberrations are generally higher. They're higher by an amount that's significantly much less than what we get with our conventional surgery. We believe that's beneficial to the patient. Our theoretical endpoint is to make them zero, and we clearly are not achieving that yet, but by shooting for that as the theoretical target, we are limiting what happens to them and that's where we are with the current state of the technology."

And a physician-investigator commented: "From a clinical standpoint, this is a step along the way because before we weren't even measuring the patient's preoperative aberrations, other than sphere and cylinder. Now we're finding other things that we find clinically significant in the population that the aberrometer can measure."

Regarding quality of vision, Dr. Schallhorn says "we're not at Nirvana yet, but we have taken the crucial first step." He believes the emphasis in refractive surgery has officially changed to quality of vision and that the industry will look back on this time of initial wavefront approvals as the turning point.