|
|
For other articles and previous issues click here. February 23, 2004 Combating
Cataracts Author and lecturer Denis Waitley, PhD, once said, “Life is the movie you see through your own eyes.” But what happens when we can’t see with our own eyes anymore? As we get older, this task becomes more and more difficult—a problem most often due to cataracts, a disease of the eyes that causes clouded vision and, if left untreated, blindness. Cataracts is more common than most people might think. “If you live long enough, it’s likely you’ll get them,” says John Ciccone of the American Society of Cataract and Refractive Surgery. According to the National Eye Institute, one-half of all Americans are afflicted with cataracts or have had to undergo cataract surgery by the age of 80.1 And while the disease is not yet preventable, cataract progression to blindness is rare, thanks to advancements in cataract surgery that have made maintaining healthy vision a simple and virtually painless process. Cataracts Defined According to Robert J. Cionni, MD, medical director of the Cincinnati Eye Institute, a cataract forms when the lens begins to become cloudy. “It is a common misconception that cataracts form on the surface of the eye, but they actually form in the lens,” he explains. “The lens is normally transparent. However, as we get older, the lens may begin to develop cloudy opacities that can distort vision. When it does so, we call the lens a cataract.” The yellowing is common in everyone’s lenses, says Cionni. “The natural yellowing process has been known to begin as early as the age of 4, but it gets more intense as we get older,” he explains. “Recent findings suggest that the yellowing filters blue light, which some believe can be as harmful to the eyes as ultraviolet light [see sidebar], but the yellowing can be caused by certain diets or hereditary components.” Even though all lenses yellow over time, only some
will develop cataracts. “The causes for cataract formation
are multifactoral,” Cionni says. “People with diabetes
are more likely to develop cataracts, as are those who have had
trauma to the eye or take certain medicines such as steroids. But,
cataracts most frequently form as a result of the natural aging
process.” Generally, cataracts afflict people over the age
of 60, Ciccone says. “As cataracts progress, they increasingly
scatter or block light traveling from the lens to the retina, which
causes vision to be cloudy or blurred.” The World War II Connection According to the Fred Hollows Foundation, a nonprofit organization dedicated to preventing blindness, “In the 1940s, British ophthalmologist Harold Ridley treated World War II fighter pilots and was surprised to find that fragments from shattered cockpit canopies, lodged in their eyes, were not causing vision problems.”3 Ciccone says that this is where Ridley got the idea for the intraocular lens (IOL), an artificial, replacement plastic lens that is inserted into the space where the natural lens had been. “The IOL takes over the lens’ job of focusing light onto the retina, which allows vision to be restored,” he says. “Ridley noticed that the eyes tolerated, instead of rejected, the canopy fragments, which were made of a plastic called PMMA [polymethyl methacrylate], so he made his first IOLs out of that material.” Prior to the introduction of the IOL, cataract surgery went through several stages of progress, Cionni says. “One of the earliest techniques is called couching, and it involves placing a needle into the eye to loosen the lens and allowing it to fall into the back of the eye, where it doesn’t interfere with vision,” he explains. “While this was performed through a very small incision, it was necessary to wear thick-lensed ‘Coke bottle’ glasses to focus light properly.” Following the introduction of Ridley’s IOL, intracapsular surgery was introduced. In this process, an incision was made halfway across the eyeball so that the cornea could be lifted to reach the lens. Once the lens and capsule surrounding it were removed, the IOL was inserted. “While this procedure got the job done, the IOL would often cause damage and dislocate out of position,” says Cionni. To combat this problem, extracapsular surgery was developed, which is very similar to intracapsular, but removes only the nucleus and cortex through a 10-millimeter to 12-millimeter incision, leaving the outer lens sack. The small sack is left in place, and the IOL is inserted into the membrane, keeping it in place more effectively. Technology Takes Off In the February 2002 edition of EuroTimes, the online newsletter of the European Society of Cataract and Refractive Surgeons, Kelman explained the reasoning behind his idea for phacoemulsification. “Finally, it occurred to me that if you take a punching bag and slowly press the knife against the punching bag, the bag will move with the knife. If, on the other hand, you rapidly accelerate the knife into the bag, the knife will remain stationary, and that is the secret of phacoemulsification.”5 Phacoemulsification works “because of the high-frequency sound waves emitted through a tiny vibrating ultrasound tip,” explains Cionni. “Because the cataract is being broken up into tiny fragments and then aspirated, a large incision isn’t needed to remove the lens.” Since its introduction, this procedure has become the method of choice for most cataract surgeons, but new advancements are being made all the time. For example, AquaLase, which was launched approximately one year ago, uses small pulses of heated fluid (approximately 4 microliters) to break up the cataract, Cionni says. Regardless of the method used, cataract surgery is one of the most common procedures performed in the United States, with approximately 2 million procedures per year, according to Ciccone. Cionni says that it is a quick and relatively easy process for patients to endure. “Speed doesn’t equal quality, but a good cataract surgery can be performed in approximately a half-hour,” he says. “Patients generally go home on the same day, and they notice an improvement in their vision almost immediately. Once you’ve had a cataract removed, there is remarkable improvement. I tell my patients that there is a 99% chance they’ll see better after surgery.” Ciccone agrees. “Many patients, especially
those who have had cataracts for a while, are amazed at how bright
and intense colors are immediately after surgery,” he says.
“They were deprived of vibrant color for so long that it’s
like they’re kids in a candy store when they see how improved
their vision is. Emotionally, it’s a big reward.” In addition to regular checkups, Ciccone recommends
using the following statements to determine whether or not cataract
surgery is right for you. “If any of these statements apply
to you, you should inform your doctor,” he says. These questions, as well as more information about cataracts, can be found at the American Society for Cataract and Refractive Surgery’s Web site at www.eyesurgeryeducation.com. The National Eye Institute also has information at www.nei.nih.gov/health/cataract/cataract_facts.htm. — Kara McDonald is an editorial assistant at For the Record. References
“A growing body of evidence shows that high-frequency blue light may lead to retinal damage and cause age-related macular degeneration [AMD],” says Robert Cionni, MD, medical director of the Cincinnati Eye Institute and a clinical investigator of the AcrySof Natural lens, which is the first IOL on the market that filters blue light. When the eye is exposed to blue light, it causes a pigment in the retina called A2E to form free oxygen radicals, which in turn can cause damage that leads to worsening of AMD, one of the leading causes of blindness in the world, he adds. James Bolling, MD, chair of the department of opthamology at the Mayo Clinic in Jacksonville, Fla., agrees. “Chronic exposure to light is one of the things we think causes degenerative eye diseases,” he has said. “We’ve known for a long time that ultraviolet light causes damage. But blue light, which is part of the visible spectrum, could actually be damaging to the retina over a long period of time.” Cionni explains that when patients have their lenses replaced with IOLs during cataract surgery, they are also removing a natural blue light filter. “Research suggests that the natural yellowing of our lenses over time acts as a blocker for blue light, so when a clear IOL is implanted, patients are losing that filter and the eye is being exposed to more blue light than ever before,” he says. While the medical world has yet to make a definitive
conclusion on whether or not blue light is as harmful as ultraviolet
radiation, Cionni believes that without blue light-filtering lenses,
cataract surgery patients are put at a potential risk. “We’ll
have to spend at least five to 10 years studying the potential protective
effect of this blue light-filtering IOLs, but for now, I believe
that evidence is strong enough to suggest that blue light-blocking
lenses are the IOLs of the future.” |
 |
 |