Exposing the LASIK Scam

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Can the Wavefront Challenge be met?
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PostPosted: Fri Sep 21, 2007 11:14 am 
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OSN SuperSite Top Story 9/20/2007

Study finds better outcomes with wavefront-guided vs. conventional PRK for myopia

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Regarding changes in higher-order aberrations, total higher-order root mean square increased 1.18 times in the wavefront-guided group and 1.6 times in the conventional PRK group. In addition, coma significantly increased by a factor of 1.74 in the conventional PRK group.

Spherical aberration increased by a factor of 2.09 in the wavefront-treated group and by a factor of 3.56 in the conventional PRK group, according to the study.

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PostPosted: Sun Oct 28, 2007 6:49 pm 
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http://www.osnsupersite.com/view.asp?rID=6057

OCULAR SURGERY NEWS U.S. EDITION October 1, 2005
Modern excimer improvements due to more than wavefront technology, optics expert says
A better understanding of the radial compensation function and other optical concepts has helped to improve LASIK outcomes.
By Tim Donald, ELS

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Dr. Holladay noted that when the three main U.S. ophthalmic excimer laser manufacturers, Visx, Bausch & Lomb and Alcon, introduced their wavefront-guided systems, they reported improvements in visual acuity outcomes over their older, conventional excimer refractive systems.

?And in fact we did get better outcomes when wavefront came along,? he said. ?But as I explained in my Barraquer Lecture last year, the three factors that resulted in the biggest improvement for wavefront had little to do with wavefront.?

Delivering the Barraquer Lecture at the American Academy of Ophthalmology meeting last year, Dr. Holladay outlined the three reasons he believes that modern wavefront-guided lasers achieve better refractive results than conventional treatments.

One reason is that the U.S. manufacturers have now taken the radial compensation function into account and included it in their ablation profiles.

The second is that the manufacturers have been required by the Food and Drug Administration to specify the minor axis of astigmatism as the size of the optical zone in astigmatic treatments, which are oval.
Dr. Holladay explained: ?With the previous standard systems, if you wanted to do a plano -4.00 X90 treatment, when you specified a 6-mm optical zone on the laser, you?d actually get a 4.5-mm-by-6-mm optical zone. But the 4.5-mm axis was the one that was critical. A few years ago I pointed out to the FDA that the smaller dimension was the one that was critical, and they began to require subsequent software to consider the smallest dimension as the effective optical zone. So previously when you did a plano -4 X90 with a standard treatment you got a 4.5-by-6-mm optical zone. But when you do it with wavefront now you get a 6-by-7.5-mm optical zone, and that?s not a fair comparison between the two types of treatment.?

The third reason is that the manufacturers have learned how to create a smoother central cornea and avoid the central islands that older systems sometimes induced, he said.

?All three of those things were included in the new wavefront treatment protocols, so there?s no question that the wavefront-guided treatments were better, but it had little to do with the wavefront measurements on the patients,? Dr. Holladay said.

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PostPosted: Tue Feb 12, 2008 2:54 pm 
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http://www.escrs.org/PUBLICATIONS/EUROT ... ionand.pdf

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There are significant limitations, he said, to the whole principle of custom ablations. ?Wavefront-guided ablations do not treat all the higher order aberrations and they induce some postoperative higher order aberrations. Every time we do a refractive procedure whether it is LASEK or PRK or LASIK, we have some induction of higher order aberrations and this is true even with custom ablations.? Dr Wilson said there are daily fluctuations in the wavefront aberrations and aberrations vary with pupil size. Aberrations, he said, change with age and variations in aberrations occur with accommodation. He also pointed out that wound healing and biomechanical changes alter aberrations after surgery. ?When you add all of these together, how can this possibly be a meaningful application? Having said all that, except in the case of patients where I am concerned about the 20 to 40 per cent additional tissue that is removed, over the last four years I have come to the point where I use custom ablation on everyone that I feel is a good candidate.

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