Custom Ablation: 1 Year and Counting
Thousands of patients are seeing clearly thanks to wavefront-guided LASIK. Here's how custom ablation stacks up against conventional laser vision correction.

At the annual meeting of the American Academy of Ophthalmology, a panel of experts discussed their experiences with wavefront-guided LASIK. This article is a recap of that discussion.

Conventional LASIK can correct lower-order aberrations such as sphere and astigmatism, but does little for -- and more importantly -- can introduce the higher-order defects of coma and spherical aberration that cause poor night vision. With customized ablations, surgeons can measure and correct a patient's unique corneal configuration, not only optimizing his visual acuity, but also improving his overall quality of vision. In clinical trials, only LADARVision improved quality of vision. (Figure 1 compares CustomCornea and conventional LADARVision as they relate to higher-order aberrations pre- and post-op.)

Fig. 1: Note pre- and post-op higher order aberrations with CustomCornea and conventional LADARVision.

Choosing Custom Ablation

Data collected from various refractive surgery centers over the past year overwhelmingly show that, compared with traditional LASIK and other custom platforms, CustomCornea achieves better clinical results.

Tom Tooma, M.D., from the TLC Laser Eye Center in Newport Beach, Calif., says. "What really made CustomCornea my platform of choice was that 85% of my patients were getting 20/20 vision and 97% of patients were getting 20/25 vision 3 months after surgery."

Mark Speaker, M.D., and Bill Tullo, O.D., collected similar results from 100 eyes at the TLC Laser Eye Center in Manhattan.

"In an early cohort of 100 CustomCornea patients, we saw significant improvements as early as day 1," says Dr. Speaker. "And the data just got better from there." CustomCornea patients achieving 20/20 or better vision at 1 day, 1 month and 3 months after surgery were 82%, 92% and 98%, respectively.

	Fig. 2: Note differences in contrast sensitivity between CustomCornea and CustomVue.

"At 3 postoperative months, 92% of our traditional LASIK patients had 20/20 or better vision, so I was really impressed by a 6% increase with CustomCornea," says Dr. Tullo.

Alan Kozarsky, M.D., of Eye Consultants of Atlanta had no trouble switching to CustomCornea. "We found the nomogram was as good as anything that we had for myopic patients before," he says. "We were getting accurate results with very few compensations to the degree that we're using the same nomogram for 20-year-olds as we are for 50-year-olds."

Wavefront Wisdom

What sets the CustomCornea system apart from other FDA-approved custom ablation systems? Unlike the Bausch & Lomb Zyoptix and the VISX CustomVue, which measure wavefronts from 6-mm pupils, LADARVision captures a 7-mm wavefront.

James McCulley, M.D., chair of ophthalmology at The University of Texas Southwestern Medical Center, found that dilating a pupil to 7.5 mm revealed 75% more spherical aberration and 46% more coma than dilating the same pupil to 6.0 mm. Dr. McCulley recommends capturing wavefront information for an area 0.5 mm wider than the intended treatment area and up to 0.5 mm wider than natural pupillary dilation.

Stephen G. Slade, M.D., from The Laser Center in Houston, agrees, saying "If you don't dilate the pupil, you're not measuring the aberrations in the periphery where they can increase dramatically."

Gathering accurate wavefront data is a vital part of planning custom ablation, but as David M. Schneider, M.D., of the Midwest Eye Center in Cincinnati points out, "These data are useless unless we can accurately place them back on the eye. If you don't have precision control and alignment through registration, which only the CustomCornea platform offers, you risk introducing misalignment errors that can cause worse problems than the errors you're trying to correct."

One indicator of CustomCornea's accuracy is how few patients require retreatment to correct residual errors. Dr. Kozarsky retreated only two LADARVision eyes since April 2003.

"Historically, our traditional LASIK enhancement rate has been 15%," he says. "Only two eyes of 965 is a significant improvement."

Dr. Tullo also reports a low enhancement rate. Fewer than 1% of LADARVision patients requested revisional surgery during the first 6 months his practice offered this service.

Improving Visual Quality

Patients who've had traditional LASIK frequently complain they have trouble seeing well at night. We now know that halos and glare in low light are caused by the higher-order defects that can be induced by the LASIK procedure itself.

"Spherical aberration is one of the most damaging aberrations to a patient's quality of vision," says Dr. Slade, "and it's the one we most frequently induce when treating the average myopic patient with conventional LASIK."

Over the past year, however, surgeons have seen a significant decrease in night-vision complaints in their CustomCornea patients. According to Dr. Tooma, data collected by Alcon showed that 13.8% of patients whose myopic astigmatism was treated with conventional LASIK said their night driving difficulty was substantially worse after their surgery.

	Fig. 4: Contrast sensitivity with conventional VISX is better than with CustomVue.

Broken down, 9.2% of patients cited more trouble with glare and 6.4% were experiencing worse halos. Only 2.2% of patients in the Custom- Cornea group developed postsurgical contrast sensitivity problems, with halos and glare dropping to below 1%, compared with traditional LASIK.

Andrew Caster, M.D., of the Caster Eye Center in Beverly Hills, Calif., explains: "We see these results not just because we're reducing preexisting aberrations, but because we're not extensively inducing new ones."

Dr. Caster measured total higher-order aberrations in 100 patients treated with CustomCornea and 27 patients treated with traditional LASIK.

Three-month dilated wavefront examination of all patients showed that compared with preoperative measurements:

• Conventional LASIK patients had a 93% increase in higher-order aberrations, compared with only 18% of patients treated with custom ablation.
• Spherical aberration increased by 98% and 38% in patients treated with conventional and custom LASIK, respectively.
• Trefoil, a third-order aberration, increased by 90% in conventional patients, compared with a 20% decrease in the wavefront group.
• Forty percent of the CustomCornea patients had an overall decrease in higher-order aberrations. None of the patients treated with conventional LASIK showed a decrease in higher-order aberrations.

Improving Contrast Sensitivity

Fewer induced higher-order aberrations may mean improved contrast sensitivity. Kerry D. Solomon, M.D., from the Storm Eye Institute in Charleston, S.C., says, "So far, only CustomCornea data are showing improved contrast compared with other conventional or custom LASIK systems."

When Dr. Caster tested pre- and post-LASIK (traditional and CustomCornea) patients he found that:

• Compared with preoperative measurements in mesopic light conditions, between 15% and 25% of CustomCornea patients showed two or more levels of improvement in contrast sensitivity at light frequencies of 3, 6 and 12 degrees per second.
• Conventional LASIK patients had poorer postoperative contrast sensitivity at almost all light levels and frequencies: Only 7% of patients showed a two-level improvement, and only at six cycles per second.
• In photopic light, between 10% and 27% of CustomCornea patients showed two levels of improvement, compared with only 7% to 15% of traditional LASIK patients.

These data show that the difference in contrast sensitivity between CustomCornea and tradition al LASIK is considerably more pronounced at mesopic light levels than at photopic levels.

"I tell my patients they'll get good results in daytime vision with CustomCornea, but they'll get a much more noticeable improvement in their nighttime vision" Dr. Caster says. Figures 2, 3 and 4 illustrate differences achieved with custom platforms vs. conventional LASIK.

Evaluating Patient Satisfaction

Clearly, these surgeons are pleased with their CustomCornea outcomes, but what do patients think? Dr. Speaker's and Dr. Tullo's traditional LASIK patients used to tell them, "This is wonderful. I can see as well as I did with my contact lenses or eyeglasses." Now, about 70% of their LADARVision patients say, "I can see better than I've ever seen before with eyeglasses or contact lenses."

Dr. Kozarsky says his patients are unequivocally happy. "My patients aren't developing the night vision or ghosting problems we've heard about so often these past 10 years."

Dr. Caster used the Johns Hopkins University Refractive Status and Vision Profile survey to evaluate satisfaction among all his LASIK patients. Preoperatively, the average patient rated his satisfaction with eyeglasses or contact lenses over the past month as 8.4 on a scale of 1 to 10 (where 10 is perfect vision). One month after surgery, the average wavefront-treated patient rated his satisfaction as a 9.0 (P=0.058). In general, 100% of CustomCornea patients said they were satisfied or very satisfied with their vision.

One Year and Counting

"Our data suggest that with CustomCornea, we can offer our patients not only improved visual acuity but also a solution to the problems that affect the overall quality of their vision," says Dr. Tullo.

"We can't measure quality of vision with Snellen acuity," says Dr. Caster, "So we have to use other criteria, such as contrast sensitivity and patient satisfaction. So far, I've been very happy with CustomCornea results."