Laser surgery¡¯s new technology¡¦ and lingering questions
by Brian P. Dunleavy
Stephen F. Brint, MD, wrote the book on laser surgery. Well, actually, he co-wrote one of the definitive consumer guides to laser surgery—¡°The Laser Vision Breakthrough¡±—with Dennis Kennedy, OD, and Corinne Kuypers-Denlinger. Back in 1991, he was arguably the first MD to perform laser in situ keratomileusis (LASIK), the most commonly used form of laser vision correction today. In short, he has treated hundreds of patients for their vision correction needs using an excimer laser.
|Those who were initially skeptical of the procedure are now coming in. Patients are doing their homework and they are more sophisticated in their knowledge of laser vision correction than even a year ago.|
—Stephen F. Brint, MD
¡°I see everyone now, from blue-collar workers to doctors, attorneys and engineers,¡± notes Dr. Brint, who serves as a clinical advisor to Alcon, manufacturer of the LADARVision excimer laser system. ¡°Those who were initially skeptical of the procedure are now coming in. Patients are doing their homework and they are more sophisticated in their knowledge of laser vision correction than even a year ago. More than anything else, though, when they come they have questions about their quality of life after surgery.¡±
Outcomes, risks and side effects with laser vision correction have been a hot topic since the U.S. Food and Drug Administration approved the excimer laser for use in the mid-1990s. The national consumer press has generally cast laser vision correction in a somewhat negative light. A USA Today article entitled ¡°LASIK Risks Understated¡± (June 28, 2001), for instance, stated that ¡°thousands are learning what [radio and TV commercials for the procedure] don¡¯t say: The surgery can cause life-altering complications that sometimes can¡¯t be fixed.¡±
The article went on to cite several troubling statistics:
• up to 5 percent of laser surgery patients experience some complication, according to industry analysts and the FDA (it should be noted that laser manufacturer-sponsored studies place this number at roughly 1 percent), including dry eye, light sensitivity, night vision problems, halos, redness, glare problems, blurred visions, headaches and tearing or burning
• LASIK is ¡°too new to know if there are any long-term ill effects beyond five years after surgery,¡± according to the Federal Trade Commission
• a study conducted by Oliver Schein, professor of ophthalmology at Johns Hopkins University, found that 41.5 percent of 176 LASIK patients surveyed said they had more difficulty driving after the surgery
This is by no means the only negative report on laser vision correction. Criticism of the procedure in newspapers and magazines and on television news programs is so common optical has come to rely on them to maintain its competitive edge over laser surgery, particularly here in the U.S. But while the flow of negative press about laser surgery hasn¡¯t ebbed, neither has the number of patients flocking to surgery centers. According to VisionWatch, a continuous consumer survey available through Jobson Research, the number of laser surgery patients increased from less than one million in 1999 to more than 1.2 million in 2000 and more than 1.8 million this year (projected).
Reasons for this abound. First, prices for the procedure have dropped in recent years, from over $1,500 per eye, to a range of $500 to $2,000 for the complete surgery, making it more affordable to more patients. Second, improvements to the excimer laser technology have increased the eligible patient population beyond myopes to includes those with astigmatism and hyperopia (approved systems can correct up to +4.00D to +6.00D).
In addition, though laser manufacturers—including Alcon, B&L, Visx and others—may not acknowledge much of the criticism, they have certainly developed technology designed to address it by making procedures more accurate and less invasive. Some of the current technology buzzwords in the laser arena are:
Wavefront: Those endorsing Wavefront technology say it will allow surgeons to correct patients to vision of 20/10 or better. Currently, surgeons ablate the cornea based on the results of corneal topography. Wavefront, however, provides a more complete picture of the cornea, measuring light rays as they pass through the eye to glean the refraction of the ¡°whole¡± eye. The system also uses smaller, minute ablations of the cornea to affect correction, reducing healing time.
Laser Thermokeratoplasty (LTK): In LTK, the doctor uses a laser to heat a series of small, dot-shaped areas of the cornea. This causes the corneal tissue to expand and make the curvature steeper. Used primarily for farsighted patients, LTK can also be performed on presbyopic patients, creating ¡°multi-focality¡± on the cornea, though, experts say, its benefits have not yet been proven. Presbyopic patients are generally treated by correcting for distance with laser, then using a spectacle prescription for near vision.
Broad Beam Lasers: A broad-beam laser uses a relatively large beam diameter (from 6 to 8 millimeters) to ablate the cornea. Because it offers the shortest procedure time, there is less likelihood of over-correction and decentration—a complication caused by movement of the pupil. A disadvantage is an increased possibility of center islands—a complication related to ablation. However, ophthalmologists have learned to manage center islands by using several short laser pulses to ablate the cornea instead of one longer pulse.
¡°Flying Spot¡± Lasers: These systems have the potential to produce the smoothest ablations with a smaller beam (less than 1mm in some cases) and use radar technology to track the eye¡¯s movement. They also have the potential to treat irregular astigmatism. Flying Spot lasers must be linked to eye tracking to ensure proper centration. A narrow beam contacts the eye at lightning speed in a pattern allowing the eye to clear in one place before contacting that area again. The laser beam covers a broad surface area, but does not penetrate as deep as in RK procedures. Unlike the broad beam, the full width of the flying spot beam is placed on the cornea during every pulse. This technology produces a smoother corneal shape and helps increase the accuracy and efficiency of the surgery.
Even with technology such as this, laser manufacturers aren¡¯t any closer to eliminating the need for eyewear altogether. Even if laser surgery exceeds projections, presbyopes, children and others not eligible for laser correction (those with autoimmune, immunodeficiency, women who are pregnant or nursing or those with a history of ocular disease or trauma, for instance) will still need eyewear. Plus, until laser surgery has a proven success and safety record over time, there will always be those who prefer traditional modes of correction. To date, experts say, less than 5 percent of all myopes and hyperopes in the U.S. have undergone laser vision correction.
¡°Fear is still the industry¡¯s biggest obstacle,¡± admits an executive with one manufacturer. ¡°But at some point, refractive surgery is going to be the standard, an accepted thing that happens to a majority of people when they reach their early 20s. I don¡¯t know how far off that is, but I can¡¯t imagine with the technology we¡¯re working on and developing for the future that it won¡¯t happen.¡±