||Historic Article on PRK|
Phoenix Magazine - January 1997
A NEW LASER EYE SURGERY
MAY BE THE VISION OF THE FUTURE - LIBERATING
NEARSIGHTED SUFFERERS FROM GLASSES AND CONTACT LENSES.
Penny Metzger looks amazingly refreshed as she strides into St. Joseph's Hospital and Medical Center at daybreak. Bright purple silk outfit, impeccable makeup, flawless manicure, good hair day. Oddly exuberant for today's circumstances, she confides: "This is all new and different. It's only the second time in my life I've had my body altered. The first time was to get my ears pierced. So I'm really looking forward to it."
Penny's biggest source of excitement isn't the novelty of surgery, but her impending liberation from glasses and contact lenses. Several years ago, she decided against radial keratotomy (RK), a surgical procedure that corrects nearsightedness by making tiny incisions in the cornea. Instead, she opted to wait for a laser procedure approved by the U.S. Food and Drug Administration late last year, called photorefractive keratectomy (PRK).
Corneal specialist Dr. Gary Mackman is a detail fanatic. Preparing for surgery, he re-checks the laser's optics, beams, focusing mechanisms and computer settings before coaching Penny through a practice session. These sessions, he explains, are critical to surgical success. "Before surgery, I want patients to hear the machine, see the flashing of the laser and smell the ozone going through the air. If you just sit a patient down and he looks up at the laser, which is kinda Star Wars-y, and you tell him to look at the target, he'll be distracted and uncomfortable. If all of a sudden he hears this funny clanking noise and feels a tear dripping down, he won't be concentrating on what he should be doing. You really have to prepare patients for this. I don't want the slightest distraction, which includes anything the patient isn't expecting or hasn't experienced."
Parroting the real procedure as closely as possible, Mackman props open Penny's eye with a steel lid speculum. Firing up the laser, he dispenses several drops of clear fluid on her eye. Blocking the laser from touching Penny's cornea, the drops help her anticipate the feeling of eye drops applied during the real procedure.
Reminding Penny to concentrate on a tiny light above her eye, Mackman explains: "When we do the real procedure, the patient's job is to stay focused on a green dot that's dead center in the middle of the laser beam," he says. "If Penny is looking at this dot, the laser beam is hitting where it should. If her eye strays even
slightly, the correction will be off. While patients are learning to target and getting used to everything, I'm watching how good they are at targeting."
Penny targets like pro, recalling practice sessions several months ago when her first eye was corrected. Dispensing numbing drops onto her
right eye, Mackman gently removes the cornea's sheer skin cover with a dull spatula. This outer layer, called the epithelium, will grow back in a
few days. Peering through a narrow operating microscope, he launches the procedure by pressing a foot pedal that delivers bursts of ultraviolet laser light into Penny's cornea. Guiding Mackman is a computer inside the laser, calculating and controlling the laser exposure as it projects an image on the cornea. A thread-thin light stream vaporizes precisely targeted cells, re-sculpting Penny's corneal curvature. The amount of corneal tissue removed - less than the thickness of three human hairs - depends on the amount of correction needed. As high-energy laser pulses - lasting only billionths of a second - generate soft clicking sounds, the microscopic layers of tissue being vaporized smell like a cap gun.
Twenty-six seconds later, Penny's eye is corrected. A half hour later, she marvels at seeing better than when she arrived only an hour earlier. She's also disappointed it's over. "This is one of the most technologically exciting things I've ever had happen to me," she gushes. "If I had a third eye to do, I'd have it done again."
Several weeks later she reports: "I can see when I wake up in the morning and before I shut my eyes at night. I've never been able to do that." Previously unable to distinguish objects more than six inches away, Penny rattles off new pleasures: Driving without glasses, reading the alarm clock across the room, waking up in the middle of the night to gaze at her Egyptian mural in the moonlight, traveling lighter. "I won't have to pack an extra carrying bag of wetting, cleaning and soaking solutions for my contacts, making sure everything is in a separate Ziploc bag." She's also gained a heightened sense of security: "I don't have to worry about losing my glasses and not being able to find the door in a crisis. Or if someone knocks my glasses off in a park or somewhere away from home, I can see who it is and know who to run away from." Meanwhile, her contact lenses are displayed in an empty soap dish, "looking up at me every time I walk in the bathroom, reminding me I don't have to obsess about all this anymore."
If you're fed up with the hassles and inconveniences of contacts or glasses, PRK is beckoning. Expected to be the most marketed medical procedure in history, laser surgery could make glasses and contacts obsolete for many nearsighted Americans - those unable to see clearly at a distance.
"PRK has a level of mainstream acceptance vastly exceeding anything that's preceded it," observes Douglas Koch, associate ophthalmology professor at Baylor College of Medicine. Researchers estimate 80 to 90 percent of the 60 million nearsighted people in the United States are eligible for the surgery. Analysts predict between 400,000 and one million people may have the procedure by 1999 - surpassing some 350,000 RK surgeries performed annually.
For folks who have been skittish about radial keratotomy, PRK is an attractive alternative. While radial keratotomy corrects myopia by flattening the cornea through deep incisions, PRK resculpts the cornea without cuts, reducing dependence on surgical dexterity. Additionally, the laser treatment doesn't weaken the cornea and doesn't leave patients seeing starbursts. The technique is also well tested. More than half a million PRK procedures have been performed in 45 countries over the past eight years. In this country, all patients in a three-year FDA study experienced improved vision: 20/40 or better in 95 percent of eyes, and 20/20 or better in 66 percent of eyes.
Although PRK doesn't require cuts or stitches, it's still surgery and therefore carries potential risks. "If you do one infinitesimal thing wrong, you can have a problem," notes Mackman. Double vision or over-correction can occur if the laser's aim is slightly off. Even if the laser is expertly operated, haziness can develop during healing if the cells under the cornea's surface cloud. This haze usually fades and disappears within six months. Other possibilities: Temporary halos or glare, and a balance problem between eyes. A balance problem can cause an altered image of the size or position of objects, making judging distance or depth perception more difficult.
There's no point in considering PRK if you're satisfied with glasses or contacts, or if you won't settle for anything less than 20/20 vision. "There's no surgery on earth that's perfect," Mackman points out. "The main problem with these procedures is there will always be a small percentage of patients who will get over-or under-corrected." But if you're willing to take the chance that you may still need glasses part time - in exchange for clearer vision without glasses during activities like driving, playing tennis or golfing - PRK may be for you.
Here's something else worth knowing: While the FDA has approved only two excimer lasers, doctors are using unapproved imported or homemade lasers. You may want to ask your doctor if he or she is using the FDA-approved Summit Technology or VISX laser. In an unusually strong warning in July, the FDA said doctors using unapproved lasers, known as "black boxes," must obtain government permission to study these devices and tell patients these lasers are experimental. "For firms or doctors that don't file investigation device evaluation applications, we're prepared to take action against them," says FDA spokeswoman Sharon Snider. "This could be a warning, seizure of their laser, an injunction or other kinds of penalties."
The Barnet-Dulaney Eye Clinic & Cataract Institute is a national leader in the use of homemade lasers. Doctors at the Phoenix facility began using one of only four unapproved custom eximer lasers in the United States in March 1995. "The question of the FDA's authority in this situation is, at best, a legal gray area," says Dr. David Dulaney. "The FDA has visited us, inspected our laser and sent us letters, but they've taken no action. We have a legal opinion that tells us that to have an engineer design and build a laser to our specifications has much legal basis." Additionally, he says, "our patient brochure that is part of our informed consent process, makes a huge point of this being a non-regulated, non-approved laser. I don't remember a single person canceling surgery because we use an unapproved laser. It doesn't seem to be an issue, frankly."
Using an unregulated procedure called laser assisted stromal in-situ keratomileusis (LASIK), Barnet-Dulaney physicians treat not only the FDA-sanctioned cases of mild to moderate nearsightedness, but higher levels of myopia - as well as farsightedness and astigmatism. During LASIK, the surgeon shaves off a thin, outer layer of the cornea. This corneal flap is then flipped up like a hinge and gently folded back. Next, the excimer laser reshapes the underlying corneal tissue. The surgeon then replaces the flap to its original position, where it naturally bonds and therefore requires no stitches. As in PRK, this reshaping of the cornea allows light rays to bend or reflect onto the retina, providing clearer vision.
The FDA's slow approval for new medical devices prompted Dulaney to build his own laser, he says. "The problem with the FDA process is that the Summit laser just approved was designed 10 years ago," he complains. "If you go outside of the U.S., where doctors have their choice of many lasers they can buy, I would venture to say that no international surgeon today would buy a Summit laser because they're totally out of date. International surgeons laugh at us. There are at least three, maybe more, advanced lasers that are made and sold in other countries. Our laser is patterned after these lasers used abroad, containing advanced software and technology that can treat any range of nearsightedness, as well as astigmatism and hyperopia [farsightedness]."
Although the first Summit laser was built 10 years ago, it has been redesigned multiple times, points out Mackman. Additionally: "With 400 Summits worldwide and 250,000 worldwide cases, this laser has the longest track record and more experience than any other lasers out there. The other machines may have extra bells and whistles, but they're not they're not necessarily more advanced because they haven't been subjected to rigorous safety and efficacy trials."
LASIK's advantages over PRK, say proponents, include the ability to correct farsightedness, astigmatism and all ranges of nearsightedness. Other benefits are reduced risk of healing haze, postoperative infection and post-operative pain. Sight is also restored faster than with PRK, where it generally takes three to six months until healing is complete and the patient's vision stabilizes.
Should you be concerned about risks from unapproved lasers? No, says Dulaney. "We have no doubt from a patient care standpoint, that what we're doing is fine." The data-gathering process used at his facility, he says, is similar to an FDA clinical trial, which "is just an accumulation of data done under a so-called protocol." With 4,000 procedures performed at Dulaney's office between March 1985 and August 1996, "we've done possibly more excimer laser surgeries than anywhere in the United States. All our complications and outcomes are documented. We have specific results we can provide to a patient. If a patient comes into our office, I can base my estimate of his outcome on a larger volume of experience than the entire Summit and VISX studies combined."
Urging consumers to postpone a decision on LASIK until FDA approval, Mackman warns, "More things can go wrong with LASIK than with PRK. The risks are higher because you're doing a hand-held procedure. There can be something wrong with the blade. You can go too far and knock the little [corneal] flap off, or the flap can fall off after you've done the surgery. We don't yet know if the benefits are worth those risks. I'm not going to subject a patient of mine to any procedure in which I can't give them reliable data to tell them what their success and failure rates are based on a legitimate scientific study."
Emory University ophthalmologist George Waring, the principal investigator for FDA clinical trials on LASIK, echoes Mackman's sentiments. "The fundamental tenant of FDA approval is that devices be proven to be safe and effective," says Waring, also a key investigator in PRK and RK trials. "The problem with these lasers is that nobody's watching. I have personal experience in seeing black-box lasers in action and seeing bad results."
If you think you've got a lot of vision-improvement choices now, grab a glimpse of tomorrow's eye-altering options: The hottest new procedure, say experts, will be a small plastic lens implanted inside the eye to treat nearsightedness. Unlike current techniques that irreversibly change the cornea's shape, the implants can be removed, returning the eye to its previous shape. Also around the corner, a laser with a tracking device. Built by a group of NASA engineers, the laser utilizes a missile-targeting system that moves with the patient's eye, eliminating PRK problems that occur when the patient diverts his eye. An intrastromal ring also is in the works. "You make an incision in the cornea and slide a plastic ring in between layers of the cornea," explains Mackman. "The shape of the cornea will change based on how thick or thin the ring is."
Finally, consider this probability: Surgical vision corrections will likely become as routine as dental work. "Over the next 15 to 20 years we're going to see different and more sophisticated types of lasers and other procedures," says Mackman. "When kids reach a certain age, they're going to be treated so they don't have to wear glasses or contacts. I think it's going to be as common as getting braces on your teeth."
What next? Hoping to accomplish the amazing, scientists and engineers across the country are working to create artificial vision to help the blind see. Striving to understand how electrical signals translate into the perception of light, researchers eventually hope to implant electrodes at the retina to do the work our eyes do. Some experts believe artificial vision could become a reality as soon as 2010. And the final frontier? "The sky's the limit," contends Mackman. "The real hope in the next century is an artificial eye that could hook up to the optic nerve in the back of the eye." Unlike artificial vision, which would require interpretation of images from brain waves and patterns, a bionic eye would work like a computerized camera that hooks up to the optic nerve and sends true pictures to the brain.
Restoring sight to millions? Nothing seems impossible these days
Cheryl A. Sweet is a Scottsdale-based freelance writer