Richard A. Levinson, M.D. > Equipment and Technology F.A.Q.

Equipment and Technology F.A.Q.

SHOULD I CHOOSE LASIK OR PRK?

LASIK and PRK both are safe and provide excellent outcomes. Both use an Excimer Laser to reshape your cornea. In PRK, the correction is placed on the surface of the cornea; in LASIK, a thin flap of corneal tissue is lifted and the correction placed on the underlying corneal bed and the overlying corneal flap then repositioned. LASIK has minimal discomfort and the visual improvement is evident within hours. PRK is slightly safer and more predictable than LASIK but has more initial discomfort and takes longer for the vision to stabilize. If the thought of the flap in LASIK makes you uncomfortable, I would strongly encourage you to consider PRK. The risk associated with the flap is small, but in 1-2% of LASIK patients, flap complications do occur. The vast majority of the flap complications are not visually threatening and are easily treatable without resultant vision loss. LASIK patients have minimal discomfort lasting for a few hours; PRK patients experience mild to moderate discomfort (watering, light-sensitivity, burning, grittiness) lasting for 48-72 hours post-op; the vision takes longer to clear up after PRK than LASIK. 98% of LASIK patients can see to drive without correction within 24 hours; PRK patients are very blurry for 2-3 days post-op, usually can see about 20/40 4-5 days post-op (well enough to pass a drivers license vision test and perform most daily activities), and slowly improve over the following weeks to months. LASIK and PRK have similar long-term visual results although, in my experience, PRK seems to give slightly better visual outcome long-term. PRK has a lower retreatment rate (1-2% vs 2-5% for LASIK) and may have somewhat less glare and dryness than LASIK. PRK may be slightly safer long-term, especially for people under 30 years of age. You will not experience any discomfort during the actual PRK procedure. During the actual LASIK procedure, you will experience mild to moderate pressure on your eye for 30-45 seconds. Once again, both LASIK and PRK give excellent long term results. In summary, PRK is slightly safer than LASIK but is more uncomfortable post-operatively and takes longer for the vision to stabilize.Custom Wavefront is available with both PRK and LASIK. Presently, 80% of my patients are choosing PRK and 20% LASIK. Interestingly, 5 years ago, the numbers were reversed. The pendulum has recently strongly swung towards PRK due to PRK’s very high safety profile and excellent visual outcome. Also, PRK is less expensive than LASIK because with LASIK there is an additional fee for the Intralase Femtosecond Laser that makes the flap. There is no flap in PRK.

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WHAT IS THE DIFFERENCE BETWEEN THE DIFFERENT EXCIMER LASERS? WHICH EXCIMER LASER DO YOU USE?

All Excimer Lasers are identical in one respect only; they all use an argon/fluoride gas laser source which delivers energy to the cornea at 193 mm wavelength. However, each Excimer uses a different “delivery system”, i.e. spot size and firing frequency to apply the Laser energy to the corneal tissue. For nearsightedness, Laser delivery systems can be divided into two groups based upon the “spot size” of the laser beam; the large spot-size lasers, called “broad beam” lasers (VISX and Summit Lasers) and small spot-size lasers, called “flying spot” lasers (WaveLight, Nidek, Technolas and Autonomous-LADAR Lasers). The VISX Star S4 actually uses a combination of “broad beam” and “flying spot” delivery. The broad beam lasers deliver a large, homogeneous, uniform energy pulse to the cornea. This results in very smooth tissue removal. The flying spot lasers apply energy in very small “dots” and create a tissue removal pattern similar to pixels in a digital image. The flying spot tissue removal is “grainier” than the “broad beam” laser pattern but has the advantage of being able to apply energy to very small areas with pinpoint accuracy. This is useful in Custom Wavefront treatments. The VISX Star S4 is the only Excimer Laser available that uses both a “broad beam” and “flying spot” technology on each patient. This offers the advantage of both laser systems. The VISX Excimer Laser is, in my opinion, the “state-of-the-art” Excimer Laser. The VISX Star S4 Excimer and WaveLight EX500 both have an “auto-tracker”, ensuring that the Excimer Laser stays centered on your cornea even if you have difficulty holding your eye still. The VISX also has “iris-registration” which automatically precisely aligns the orientation of the astigmatism correction. The orientation of the astigmatism is critical for accurately treating astigmatism. The WaveLight does not have “iris-registration” so we have to visually approximate the orientation of the astigmatism correction, which isn’t as accurate as VISX for treating astimagtism. The WaveLight EX500 fling-spot Excimer Laser does have the advantage of being a very fast-firing Laser. This is advantageous in treatments of long duration, especially in hyperopic (farsighted) treatments. In longer treatments, the cornea has a tendency to dry out and this can result in decreased accuracy of the Laser correction. The WaveLight is more predictable on hyperopic corrections.

I have used the Technolas Excimer Laser, a “flying spot” Laser, but found it to be slow and it removes too much corneal tissue. The long treatment time results in increased dehydration of the cornea, and inconsistent Laser outcomes. Also the Technolas removes up to 50% more corneal tissue than the VISX for any given power and diameter optical zone. The extreme amount of tissue removed by the Technolas can structurally compromise the cornea and is a major reason most Laser Surgeons have stopped using the Technolas. The Autonomous (LADAR) Excimer Laser takes almost twice as long as the VISX for treating nearsighted patients, and this is somewhat of a problem. Also, the Autonomous is a more expensive laser to operate, costing about $250 more per eye.

At this time, I use the VISX Star S4 with CustomVue (Wavefront) Technology and the WaveLight EX500. I use the VISX for myopic (nearsighted) and astigmatism correction and the WaveLight for hyperopic (farsighted) correction.

The NIDEK Excimer Laser is the Laser-of-choice of “cut-rate” Laser Centers. They use the NIDEK because it is a less expensive Laser than the VISX. I am not aware of any Laser Centers, other than the “cut-rate” Laser Centers, that use the NIDEK Excimer Laser in the Denver area. The only advantage for the NIDEK is that it is less expensive to operate.

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WHAT ARE THE ODDS OF ELIMINATING MY NEED FOR GLASSES OR CONTACTS AFTER LASER VISION CORRECTION?

In the thousands of cases of Laser Vision Correction I have performed, 90% of patients have 20/25 or better vision without correction, and 97% of patients will see well enough to pass a driver’s test (20/40) without correction.

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WHAT IS THE INTRALASE LASER AND iLASIK?

First of all, I think the IntraLase is wonderful and, although it does add extra expense to the LASIK procedure, the improved safety and visual results with the IntraLase is money well spent.

What is the IntraLase. This is a little tricky, so pay attention! In LASIK a thin flap of tissue is lifted off the top of the cornea. The underlying cornea is then reshaped with the Excimer Laser and the corneal flap repositioned. Two technologies are presently available for making the corneal flap. One, the older technology, is the Microkeratome, a mechanical device that uses a metal blade to create the LASIK flap. The other, newer technology for lifting the flap is the Intralase Laser. (The Intralase is a separate laser from the Visx Star S4 Excimer Laser. Once again, we use the Excimer Laser to reshape the cornea in LASIK and PRK. We use the Intralase to create the corneal flap in LASIK). The mechanical Microkeratome works extremely well and has been used safely and successfully in millions of Lasik procedures for over ten years. However, the Intralase is better technology because of increased safety and better visual results. The IntraLase uses billions of little bubbles, instead of a metal blade, to create the LASIK flap. Patients tend to see better (7% better to be exact) after LASIK with the Intralase than with the Microkeratome. But even more importantly, the Intralase is safer than the Microkeratome. The Microkeratome is very safe but the Intralase is safer, having a lower incidence of flap complications. And when the rare complications do occur with the Microkeratome or the Intralase, complications with the Microkeratome tend to be much more difficult to manage than complications with the Intralase. There is an additional fee for the Intralase.

iLASIK is the name we use to describe LASIK when we use the Intralase femtosecond Laser the VISX Star S4 CustomVue Excimer Laser together.

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WHAT DOES 20/20 OR 20/40 VISION MEAN?

The 20/20 nomenclature is an old system devised by Hermann Snellen, a Dutch Ophthalmologist, in 1862. 20/20 means the viewer can see at 20 feet what a “normal” person would see at 20 feet. 20/40 means the viewer sees at 20 feet what the “normal” person can see at 40 feet, i.e. the viewer can’t see quite as well as “normal”. This system is somewhat misleading. 20/40 vision is not twice as bad as 20/20 vision. In fact, most people with 20/40 or better vision can, and usually do, function without wearing correction. 20/40 vision or better is required to pass a drivers test in Colorado. After LASIK, 97% of patients have 20/40 or better vision and over 80% have 20/25 or better vision. In the “real world” the difference between 20/20 and 20/25 vision is negligible. Interestingly, Snellen used test subjects to determine what people with “perfect” vision could see, and called that level of vision “20/20”. It turns out that his test subjects were slightly nearsighted and, therefore, people with perfect vision actually see better than 20/20. The “perfect” human eye can see slightly better than 20/10!

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WHO MAKES SURE YOUR LASERS ARE WORKING CORRECTLY?

Each Excimer Laser and Femtosecond Laser costs approximately $500,000. It is too expensive for individual doctors to buy the numerous Lasers needed to offer the full spectrum of technology required to provide state-of-the-art Laser Vision Correction. I use the Lasers at TLC Laser Vision Center because they have made the commitment to provide the most advanced technology available. They have both the VISX and WaveLight Excimer Lasers and the Intralase Femtosecond Laser. No other Laser Center in the Denver area has both the VISX and WaveLight Lasers. Along with this commitment to offer the most advanced technology available, TLC has been meticulous in continuously maintaining and calibrating their equipment. I, and over a dozen other Laser Surgeons have used the equipment at TLC since 1996, and I have not had one complication due to equipment failure. Both VISX and Alcon, the manufacturers of the Lasers, have strict maintenance and daily calibration verification systems that TLC meticulously follows.

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WHO IS A GOOD CANDIDATE FOR LASER VISION CORRECTION?

Laser Vision Correction is well suited for active people who find glasses and contacts to be a nuisance and those who simply don’t want to be so dependent on corrective lenses. If you wear glasses or contacts and are over 18 years old, you are probably a good candidate. Your lens prescription should be stable at distance for at least one year and you should be free of medical problems related to your eyes, primarily cataracts. You should also make sure you have realistic expectations about Laser Vision Correction. Although Laser Vision Correction has the potential to greatly reduce or eliminate dependence on corrective lenses, there can be no assurance that you will obtain perfectly corrected vision. The vast majority of patients can function without glasses or contacts after Laser Vision Correction, although, occasionally, Laser Vision Correction patients may wear a mild glasses correction to fine-tune their distance vision. People who are most satisfied with the results of Laser Vision Correction clearly understand the potential risks and side effects and have realistic expectations of what their vision will be like after surgery.

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CAN LASER VISION CORRECTION HELP ALL VISION PROBLEMS?

There are 4 types of refractive problems that Laser Vision Correction can correct::

1. Myopia (nearsightedness) occurs when the cornea is too steep relative to the length of the eyeball. As light enters the eye, the visual image focuses in front of the retina, resulting in a blurred or distorted view. Without correction, nearsighted people have blurry distance vision but can see well at near. The FDA approved the use of the Excimer Laser for Myopia in November, 1995. Laser Vision Correction works extremely well for nearsightedness. In myopia, the Excimer Laser flattens the central cornea, focusing the image on the retina.

2. Astigmatism (asymmetrical cornea) occurs when your eye is shaped like a football, unlike a normal eye, that has a round shape similar to a basketball. Uncorrected Astigmatism causes blurred vision both at near and far. In April 1997, the FDA approved Excimer Laser correction of Astigmatism. The Excimer Laser works extremely well for treating Astigmatism.

3. Hyperopia (Farsightedness) occurs when the cornea is too flat relative to the length of the eyeball. Hyperopia requires people to exert focusing power to see at near and far. The normal eye only has to exert focusing power to see at near. When farsighted people are young and have ample focusing power, they usually see well both at near and far. However, with aging, people lose focusing power; farsighted people will begin to notice difficulty seeing at near and as they continue to age, will also note difficulty focusing at distance, as well. In November, 1998 the FDA approved the Excimer Laser for the correction of Hyperopia. The Excimer Laser works well for correcting Farsightedness. In farsightedness, the Excimer Laser steepens the central cornea, focusing the image on the retina.

4. Presbyopia is an age-related condition that causes people from the mid-forties and older to need reading glasses or bifocal lenses to read. Presbyopia is a result of loss of elasticity in the lens of the eye. Presbyopia cannot currently be corrected with the Excimer Laser. The Excimer Laser can, however, used to create a condition called Monovision, where one eye is corrected for near vision and the other is corrected for distance vision. I know monovision may sound somewhat ridiculous, but monovision actually works very well and allows most patients over the age of 45 to function without glasses correction for both reading and distance vision.

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WHAT ARE THE LONG TERM RESULTS? WILL MY EYES DETERIORATE IN THE FUTURE?

Since 1987, millions of Excimer Laser procedures have been performed worldwide. Laser Vision Correction appears to be very stable, and recurrence of refractive error after six months is uncommon. There does not appear to be any increased risk of macular degeneration, cataracts, retinal detachments or any other eye problem related to LASIK treatment. The one long term risk that has been identified with Laser Vision Correction is “ectasia”. In approximately 1 in 2000 Laser Vision Correction patients, the cornea will develop weakening and instability, i.e. ectasia, after Laser Vision Correction. Ectasia results in progressive blurry vision that may not be correctable with glasses, contacts or Laser retreatment. With adequate pre-operative screening, we can identify, and not operate on, patients that are at risk of developing ectasia. However, ectasia has rarely been reported in patients after Laser Vision Correction that have no known risk factors. Ectasia does occur in the general population, i.e. people that have never had Laser Vision Correction, in approximately 1 in 2000 people so not all cases of post-op ectasia may be due to the Laser Vision Correction

The “K” in LASIK stands for “keratomeleusis”, which is the “flap cutting” step in LASIK. Keratomeleusis, without Lasering, has been performed since 1959, primarily in South American, as a treatment for extremely high nearsightedness. So we, in fact, have over 40 years experience with the most “invasive” step in the LASIK procedure, the cutting of the flap. From this 40+ years of experience we have learned how deep we can safely treat the cornea without causing long-term damage to the cornea. Arguably, we have more “long term” information on the “flap cutting” in LASIK than we do with soft contact lenses, which have “only” been available for about 35 years.

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WHAT IS WAVEFRONT ANALYSIS AND CUSTOM CORNEA TECHNOLOGY? HOW GOOD IS IT?

Wavefront analysis is a new way of analyzing the cornea. Wavefront technology was initially developed by astrophysicists to improve the quality of optics in telescopes. Wavefront analysis involves sending a reference light ray into a telescopic mirror system and measuring the reflecting light ray as it exits from the mirror system. Sensors can detect the location of the exit reference light ray. The difference between the position of the reflected wave and the location of where the wave should theoretically have been in a “perfect” system can be determined. Then, by adjusting the reflecting mirror surface with small servo-mechanical “suction cups” located on the backside of the mirror, aberration (distortion) can be removed from the mirror system. Wavefront analysis has significantly improved the quality of images in telescopes such as the Hubble Telescope. Wavefront analyzers are now available for analyzing human visual systems. I use both the VISX CustomVue and the WaveLight Wavefront systems. Both work well but I found the results to be better with the VISX CustomVue Wavefront system. The VISX wavefront system measures each eye and identifies, and treats, each eye based on that eye’s unique corneal shape. It is a true custom treatment. The WaveLight uses pooled wavefront measurements to optimize its treatment pattern, but the WaveLight is not a true custom treatment.

VISX Custom Wavefront adds another level of accuracy and predictability to Laser Vision Correction and increases the quality of vision after Laser Vision Correction, especially at night or in dim lighting situations. Wavefront does add $250 per eye to the cost of LASIK and PRK, but I feel it is worth the extra expense. Not every patient is a candidate for Wavefront or even needs Wavefront, especially if you have small pupils (under 5 mm in dim light). Please contact my office if you have more specific questions regarding Wavefront-guided Laser Refractive Surgery.

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SHOULD I WAIT FOR LASER VISION TECHNOLOGY TO GET EVEN BETTER?

Anytime we deal with advanced technologies we have come to expect continuous, ongoing improvements. And you could argue why buy a new car, a new computer or undergo LASIK today when the technology will be “better” in the future. However, at least with Wavefront guided LASIK, the Laser Vision technology appears to be stabilizing. We can look 3-5 years down the FDA “pipeline” for new technologies, and there is presently nothing “revolutionary” on the horizon. I would expect in the future for the FDA to approve the use of Wavefront technology on a wider group of patients, including Farsighted patients. However, the Wavefront-guided LASIK we have today gives excellent results for 98% of patients and it appears to me that waiting for future technologic improvements will not give you access to significantly better visual outcomes.

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WHAT IS CK?

CK (conductive keratoplasty) is a refractive surgical procedure somewhat similar to LASIK. CK reshapes your eye by using a small needle-like probe that applies radio-wave energy to the surface of the cornea. The radio-wave energy causes the corneal tissue to slightly “shrink”, thus reshaping the cornea. By applying the energy in a specific pattern and inducing a controlled “shrinking” of the corneal tissue, refractive changes can be induced. CK is an outpatient procedure that takes less than a minute to perform. The cornea is numbed with eye drops. The needle-like probe applies the energy in a circular pattern approximately three millimeters from the center of the cornea. Depending on how much correction is required, anywhere from 6 to 18 “spots” of energy are applied. There is mild to moderate discomfort after CK. The refractive change is almost immediate.

CK can only treat mild amounts of farsightedness; it cannot treat nearsightedness or astigmatism. This limits its usefulness. If you have good uncorrected distance vision, (and are over the age of 45), CK can also be used to create Monovision, allowing you to read without glasses. In monovision your non-dominant distance eye can be treated with CK, making it a reading eye. (This will blur your distance vision in the treated eye, but with both eyes open, you can see both distance and near.) CK does not give you back the focusing power you lost with age.

CK has three major drawbacks. The first drawback is that CK’s effect regresses within 1-2 years, and CK is not as effective if reapplied a second time. The second drawback is that CK not only cannot treat astigmatism, but it can actually induce astigmatism, which then is difficult to correct. The third drawback is the very limited number of patients that are actually candidates for CK.

I see no advantage to CK over LASIK. In fact, I would recommend LASIK over CK. LASIK is much more precise than CK and can treat a much wider range of farsightedness, astigmatism and nearsightedness. LASIK uses an Excimer laser with 1/4 micron (1/200 of a hair) precision to reshape your eye. CK uses radio-waves to shrink the corneal tissue and does not have the precision of LASIK. LASIK can be repeated, if necessary, to enhance the visual outcome. CK cannot be enhanced. LASIK has a very stable long term effect; CK’s effect regresses over 1-2 years. LASIK can treat astigmatism (just about everybody has astigmatism), CK cannot treat astigmatism. CK and LASIK cost approximately the same, take about the same amount of time to perform, regain vision at about the same rate, and are both performed with only eye drops to numb the eye. LASIK has very minimal discomfort; CK is more uncomfortable than LASIK, especially for 2-3 days after the procedure. I don’t really understand why anyone would choose CK when LASIK and PRK is available.

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DIDN’T A MOUNTAIN CLIMBER WHO HAD PREVIOUS REFRACTIVE EYE SURGERY HAVE A PROBLEM WITH HIS EYES WHILE CLIMBING MT. EVEREST?

Yes. However, the climber had Radial Keratotomy (RK) performed many years before he climbed Mt. Everest. He did not have LASIK or PRK. In RK, deep incisions are made in the cornea which flatten the cornea by structurally weakening the cornea. At very high altitudes, such as Mt. Everest, the decreased atmospheric pressure caused the cornea to pathologically flatten further. This caused the patient to experience the onset of farsightedness, making it very difficult for him to see. This would not occur with LASIK or PRK because the cornea is not structurally weakened by these procedures.

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WHAT IF I DON’T GIVE THE RIGHT ANSWERS WHEN YOU MEASURE MY EYES? WILL I GET A BAD RESULT?

Absolutely not!!! I realize some people get extremely nervous that they will give the “wrong” answer when I do the “which is better, 1 or 2” measurements. This measurement, which is called the “refraction”, is used for calculating the amount of tissue the Excimer Laser will remove, so it is important. However, when I am doing the refraction on you I am not obediently following your responses. Before I even start your refraction, I will take computerized measurements of your eyes which will give me an extremely precise “objective” refraction. I then give you the opportunity to “fine tune” my objective measurements. All you need to do is tell me which of the two choices I give you make the letters look clearer. If neither choice is better, that is actually the end point I want; that means the refraction we have attained is precise because any subtle adjustment to your refraction is making your vision blurrier. To add even more precision, I will have my ophthalmic assistant refract you, and I will refract you myself, twice. These three “human” measurements, and the computerized “objective” refraction are then compared, and they better be extremely close, otherwise, I will keep rechecking your refraction until I get a consistent refraction result. And to add even more precision, consider Custom Wavefront.Wavefront measurements use a scanning Laser mapping of your eye; we avoid having to depend on the the refraction, and your responses.

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I HAD A LASER VISION CONSULTATION WITH A “LASER CENTER” AND THEY CLAIMED THAT THEY HAD ACCESS TO “SPECIAL” TECHNOLOGY AND USED “SPECIAL” TECHNIQUES THAT NOBODY ELSE USED AND THAT THEIR RESULTS WERE BETTER THAN EVERY OTHER LASIK SURGEON’S RESULTS. WHAT MAKES THEM BETTER?

eware of any Laser Vision Center that makes unreasonable claims, including claims that they are the “best”, were the “first”, or that they are the “only one” to do something “special”. Laser Vision Correction is not a secret, magical, mystical procedure. Laser Vision Correction is a highly predictable, reproducible procedure based on the research and shared experience of thousands of extremely smart scientific investigators and surgeons who have collectively performed over 20 million Laser Vision procedures. I attend two major Laser Vision meetings a year – The American Academy of Ophthalmology meeting every fall and the American Society of Cataract and Refractive Surgeons meeting every spring. These meetings present to all Laser Vision Surgeons the most up-to-date information on Laser Vision Correction, based on the shared research and clinical experience of the top Laser Vision Surgeons in North America, Europe and Asia. This information is widely disseminated and readily available to all Laser Surgeons, around the world. The goal is to continuously improve Laser Vision Correction results by sharing information and experience about what works, and what doesn’t work, in Laser Vision Correction.

In my opinion, any Laser Vision Surgeon who claims to do something “special” is either arrogant and making exaggerated, boastful claims (remember, this is Laser Vision Surgery, not the World Wrestling Federation!), or is exposing you to unnecessary risk by using techniques that are “special” only because no other experienced Laser Vision Surgeon deems those techniques safe and/or beneficial.

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DOES NASA ALLOW ASTRONAUTS TO HAVE LASER VISION CORRECTION?

Yes! The following is a press release from AMO, the manufacturer of the VISX Excimer Laser and the IntraLase Femtosecond (Bladeless Lasik) LASER, which, when used together, is called iLASIK.

NASA approves iLASIK for astronauts SANTA ANA

Calif. Sept. 21, 2007 / PRNewswire / – Advanced Medical Optics, Inc. (AMO) today announced that the National Aeronautics and Space Agency (NASA) has approved the company’s LASIK technologies for use on U.S. Astronauts. The NASA decision was made following review of extensive military clinical data using AMO’s Advanced CustomVueT LASIK with the IntraLase™ Method, which showed the combination of technologies provides superior safety and vision. Approved for use on consumers almost a decade ago, more than 11 million LASIK procedures have been performed to-date, making it the most-common elective surgical procedure in the U.S. But it wasn’t until LASIK developed into an all-laser procedure that NASA approved it for use on pilots, mission and payload specialists who face extreme, physically demanding conditions in space. The all-laser LASIK technologies, which utilize wavefront guided and femtosecond lasers, have also been cleared for U.S. Military personnel, including most recently Air Force pilots. NASA’s approval is further evidence that today’s LASIK exceeds all established standards of safety and effectiveness,” said Steven Schallhorn, M.D., Retired captain of the U.S. Navy, investigator in multiple studies involving use of LASIK and other refractive surgeries for treatment of nearsightedness, farsightedness and astigmatism, and Medical Director for Optical Express. “NASA followed the Naval Aviation clinical studies closely with a particular interest in both safety and quality of vision under extreme conditions. Wavefront guided and femtosecond lasers were proven to provide excellent safety with consistent visual results of 20/20 or better. LASIK was able to withstand even the most extreme rigors of warfare and flight. All surgical procedures have risks, but with this exceptional track record, the average consumer has nothing to fear from LASIK.”

LASIK is a two-step procedure. The IntraLase™ FS (femtosecond) laser replaces the hand-held microkeratome blade historically used in creating LASIK corneal flaps — the first step of the procedure. The computer guided, ultra-fast laser virtually eliminates almost all of the most severe, sight threatening LASIK complications related to microkeratomes. The laser creates an optimal corneal surface below the flap, allowing for better visual outcomes from the second step of the procedure where wavefront guided technology maps, and then custom-corrects vision based upon the unique characteristics of an individual’s eye. This sophisticated measurement provides 25 times more precision than measurements using standard methods for glasses and contact lenses. LASIK’S FINAL FRONTIER Though LASIK has been around for almost a decade, concerns about the harsh aviation environment prevented its use. To date, aeromedical professionals have been cautious of employing the procedure on Military aviators who frequently encounter environmental extremes such as high altitude, dry air, wind blast and “G” forces. In space, these and other conditions add even higher levels of concern due to the extreme precision needed during flight and space walks. Dr. Schallhorn, himself a Retired naval aviator, spearheaded the majority of the Defense Department’s research in laser vision correction. Some notable results of the many clinical trials conducted include: An evaluation of Custom LASIK in 100 Military personnel showed that 95 percent achieved 20/20 uncorrected vision or better; these patients, on average, were previously only able to read the first line (the big “E”) of the vision assessment chart.

1 In a study of different methods to create the LASIK flap, 370 naval personnel underwent bilateral wavefront-guided LASIK with either the femtosecond laser or microkeratome blade. One week after surgery more than 76 percent of femtosecond laser patients achieved an uncorrected visual acuity of at least 20/16 (better than 20/20) compared to 58 percent of microkeratome patients.

2 In an evaluation of 785 aviators, 89% of Navy pilots rated their ability to land on an aircraft carrier as moderately to significantly better after laser vision correction. None said it was worse after surgery.

3 A separate study determined that over 90 percent of marksmen had improvement in marksmanship skills after laser vision correction; a significant result given the visual precision of marksmen.

4 “Today’s news further validates AMO as the global leader in laser vision correction technologies,” said Jim Mazzo, AMO chairman, president and CEO. “Our Advanced CustomVueT LASIK with the IntraLase™ Method is the only procedure in the U.S. to incorporate the technologies specifically approved for use by NASA.” In the U.S. Laser vision correction market, the Advanced CustomVueT LASIK procedure with the IntraLase™ Method has become the new standard and is rapidly becoming the most widely performed laser vision correction procedure. In fact, the majority of premier ophthalmic teaching institutions, including Duke University Medical School, the Wilmer Eye Institute at Johns Hopkins, the Bascom Palmer Eye Institute at University of Miami, and Stanford University, totaling over 16 domestic and international teaching institutions use Advanced CustomVueT LASIK with the IntraLase™ Method to train the next generation of LASIK surgeons. Advanced CustomVueT LASIK with the IntraLase™ Method The Advanced CustomVueT laser vision correction procedure stands in a class of its own with the broadest range of FDA-approved indications. When combined with the power and precision of the IntraLase™ Method, the Advanced CustomVueT procedure represents the most advanced LASIK procedure available to patients today. The IntraLase™ FS laser, the first technology for a blade-free LASIK procedure, replaces the handheld microkeratome blade historically used in creating LASIK corneal flaps — the first step of the procedure — with a computer guided, ultra-fast femtosecond (femtosecond) laser. The IntraLase™ laser virtually eliminates the majority of the most severe sight-threatening LASIK complications related to use of the microkeratome.

5 Additionally, by creating an optimal corneal surface below the flap, the IntraLase™ Method provides for better visual outcomes — taking patients to 20/20 vision and beyond.

6 More than one million LASIK procedures using the IntraLase™ Method have been performed.

Source: Captain (Retired) Steven C. Schallhorn, “US Navy study: Custom PRK versus custom LASIK”. Presented at the European Society of Cataract and Refractive Surgeons annual meeting; September 8, 2006; London, UK.

Source: Tanzer DJ, Schallhorn SC. Comparison of visual outcomes with femtosecond and mechanical microkeratomes for wavefront-guided LASIK. Presented at the American Academy of Ophthalmology annual meeting; November 13, 2006; Las Vegas, NV.

Source: Schallhorn SC, Tanzer DJ, ‘Refractive Surgery in Naval Aviation’, Presented at the Aerospace Medical Association annual meeting, May 15, 2006, Orlando, FL.

Source: Captain (Retired) Steven C. Schallhorn, “Refractive Surgery in the Navy”, Presented at the Aerospace Medical Association annual meeting; May 17, 1999; Detroit, Michigan. Source: Binder PS: “One thousand consecutive IntraLase laser in-situ keratomileusis flaps” Journal of Cataract and Refractive Surgery. V32. June 2005.

Source: Durrie DS, Kezirian, GM: “Femtosecond Laser versus Mechanical Keratome Flaps in Wavefront-guided Laser in situ Keratomileusis: A Prospective Contralateral Eye Study” Journal of Cataract and Refractive Surgery, V31, Jan. 2005.

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I was told that the WaveLight wavefront “optimized” Excimer Laser is more precise than the the VISX Star S4 CustomVue Excimer Laser system. Is that true?

Both Excimer Laser systems are based on wavefront measurement technology. The WaveLight Excimer averages wavefront data from a large sample of human eyes to determine your “wavefront” treatment. The WaveLight uses a “one-size-fits-all” wavefront treatment profile. The WaveLight Excimer does not custom treat each eye based on the unique wavefront profile for that eye. The VISX CustomeVue Wavefront system actually measures your eye and maps the unique, specific “higher order aberration” (HOA) profile for your eye. The VISX Wavefront system generates a specific wavefront treatment profile each patient. No two eyes are identical and the VISX system identifies, and treats the unique wavefront higher-order-aberration pattern for each eye. The WaveLight Excimer Laser does not custom treat each eye. Is this significant? In a study presented at the 2008 American Academy of Ophthalmology meeting Nov 7, 2008 in Atlanta, Jack Holladay M.D. presented the results of a study comparing the results of the WaveLight and VISX CustomVue Excimer Lasers. Approximately 100 eyes were Lasered with each system and the results compared. The VISX system had 88% of eyes with higher order aberrations (HOA) the same or better after treatment while the WaveLight had only 59% of eyes with HOA the same or better. The conclusion of Dr. Holladay’s study was that “wavefront guided ablations (the VISX CustomVue Wavefront system) provides the best optical results for the vast majority of patients, especially with medium or high higher-order aberrations pre-op”. This suggests, at least in this study, that the VISX CustomVue Wavefront system gave better results than the WaveLight wavefront “optimized” (one-size-fits-all) system.

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