Comparing Excimer Lasers For Vision Correction Surgery

Does the type of laser make any difference? What about excimer lasers?

Wavefront-guided excimer lasers are the latest generation lasers, which boast the most advanced laser algorithms (as outlined by Jack Holladay, M.D.). Co-dydramol the wavefront-guided lasers, therefore, tend to result in the smoothest post-op corneas and the lowest degrees of higher order aberrations (HOA’s) in vision, which translates into sharper vision with greater contrast sensitivity and less risk of halos, ghosting, and other night vision disturbances.

But, is one brand of laser better than another? In order to answer this question and back up the answer with data, one needs patients’ eyes randomized to treatments with two or more different excimer lasers and prospective follow-up of results. At this point in time, there is an extreme paucity of this type of study that compares the most modern of lasers across the board. There certainly are a few studies that compare older generation lasers.

A single study that compared custom LASIK, that is wavefront-guided (WFG) LASIK, utilizing two separate excimerlaser systems is underway and has presented preliminary data. In this study, Alcon’s CustomCornea and the Bausch and Lomb Zyoptix system’s results were compared. In this study, fifteen patients (30 eyes) were treated with CustomCornea and 15 patients were treated with the Zyoptix system and patients have been followed up to one month. All of the patients’ flaps were created with the Intralase femtosecond laser (IntraLASIK).

At one month post-op, their report states, “the percentage of eyes with uncorrected visual acuity (UCVA) of 20/20 and 20/40 was similar with 93% and 100%, respectively, for CustomCornea eyes and 90% and 97%, respectively, for Zyoptix eyes. A difference between the two groups is in the percentage of eyes with UCVA of 20/16, 20/12.5, and 20/10 with 80%, 47%, and 13%, respectively, for CustomCornea and 70%, 10%, and 0%, respectively, for Zyoptix.

Obviously, both sets of results show extraordinary results; however, Alcon’s CustomCornea outperformed the Zyoptix system in this small study with short-term follow-up. Longer-term follow-up may indeed change these early results, as post-op refractions can be unstable for at least several months following LASIK.

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A review of the literature reveals no other comparisons between the most advanced, wavefront-guided, excimer lasers. There certainly are theoretical and methodical differences between machines, but these differences may not necessarily translate into any definite differences in visual acuity outcomes.

Will You Have A Choice As To Which Excimer Laser Is Used?

At the present time, the large majority of excimer lasers procedures in the U.S. are being completed on VISX machines. VISX presently dominates the U.S. market and most reports suggest that approximately 70% of excimer lasers are being completed with VISX machines. Therefore, statistically speaking, you are most likely to have your excimer lasers on a VISX machine if you reside in the U.S. There’s good reason for this: VISX has an excellent track record and remains on the cutting-edge of technology with their machines and broad FDA approval to treat myopia, hyperopia, and astigmatism, especially with their wavefront-guided CustomVue Star S4 excimer laser system.

If you intend to have your excimer laser procedure and a VISX machine will be used, I would strongly advise you to have your procedure completed with the CustomVue Star S4 excimer laser system, and if you have any significant astigmatism (greater than 0.5 Diopters), I would also advise that you shouldn’t hesitate to be sure their latest invention, Iris Registration, is also used. This latter technology images the detail of the iris during the wavefront data-gathering phase of the procedure and then appropriately rotates the beam of the excimer lasers based on the rotational movement of the eye during the laser procedure itself. Iris registration probably plays little role in the procedure in patients who have no significant astigmatism.

Likewise, with other excimer lasers (and there are many excellent systems), I would strongly advise that you take it upon yourself to be certain your eye surgeon is using the latest technology because, as the studies have shown, it makes a difference in your outcome! Don’t listen to any advice that suggests “it is all in how your surgeon uses the machine” and/or “it is the surgeon that makes all the difference”. If that were true, why wouldn’t all refractive surgeons is using the Summit Apex excimer lasers that were FDA approved in 1995, which has now been largely abandoned? Well, for the same reason that you’re probably not viewing this on a 1990 vintage computer… they both keep improving! Now trust me, I’m not denying that your surgeon is the most important element here. He or she definitely is. The best surgeons also tend to use the latest technology, which is partly how they stay on the forefront and get the best results.