March 2004

By Selene Yeager

If the octopus had been any clearer, it would have been in her lap. Only it wasn't. It was a safe distance away, as was an eel, which Dr. Helena Karlberg could also see with shocking clarity, even though the water was deep and the sky was dark. "I couldn't believe how crisp the marine life was, even at night," raves Karlberg of Houston, Texas. Day dives were even better. What once appeared as muted marine life were now brilliant parrotfish and detailed coral. "Everything had magnificent clarity," says Karlberg.

"I've been nearsighted for years," says Karlberg. "I tried soft contacts, but they dried out my eyes, and I never saw well with them. I didn't care for glasses. So, I would often just go blurry when I wasn't working."Then a year ago, Karlberg took up scuba. "That was the deciding factor for me to get my vision corrected. Even in good visibility, I couldn't fully appreciate the beauty of the marine environment. In poor visibility, I could barely recognize my buddy."

Karlberg scheduled herself for Lasik--a popular laser vision surgery. Because she also had astigmatism and large pupils, two characteristics that can make Lasik difficult, Karlberg had to have two surgeries. A few weeks after the second, she was 99 feet down in Cozumel, agape at the dazzling coral reefs with no regrets. "I just booked a trip to the Gulf. I can't wait to see the Flower Gardens."

Eye, Eye Captain

On dry land, vision accounts for about 65 to 80 percent of our perception. Fifty feet under water, where we can barely smell, hear, taste, or touch, the amount of information we depend on our eyes for increases exponentially.

"Almost 100 percent of your scuba diving experience is what you see," says Donald Teig, O.D., director of the Institute for Sports Vision in Ridgefield, Conn. At the very least, poor vision detracts from your enjoyment of the sport. At worst, it compromises your safety, Teig says, especially if you struggle to read your instruments, sight the boat or identify your buddy.The culprit behind most vision problems is what is known as "refractive error." To see clearly, your cornea and eye lens must bend (refract) light rays so they focus on the light-sensing retina at the back of your eye. The retina transforms those rays into impulses, which it delivers to the brain, and voila, fish and fauna in their crisp, candy-colored glory. When your eyeball is misshapen, the rays can't refract correctly, so the picture is distorted. The basic types of refractive error are:

Myopia > Nearsightedness, which affects about 70 million people in North America, is caused by a cornea that is too long, so only nearby objects are clear.

Hyperopia > Less common than myopia, farsightedness is caused by a cornea that is too short, leaving objects in the distance clear, but those nearby a blur.

Astigmatism > The cornea is irregularly shaped, so vision is blurry distant and near. Astigmatism is not an uncommon condition, and many people have some degree of it.

Presbyopia > With age, the eye lens loses flexibility, making focusing on nearby objects difficult. Almost everyone develops presbyopia by age 50, which is why people wear "reading glasses." Fortunately, scuba masks magnify objects under water about 30 percent, so mild presbyopia is fairly tolerable during dives.

There are many ways to correct refractive errors, the most popular being glasses and contact lenses. Divers also can purchase special masks with prescription lenses. But not all divers are satisfied with these choices. Prescription masks can be costly and inconvenient for infrequent divers. Glasses are not compatible with splashing waves and scuba masks. And though many divers do well with contact lenses, some have trouble wearing them comfortably in the wind and water. Among these divers, there's a growing interest in new vision-correction methods like Lasik. But divers worried about the dangers of pressure, bubbles and decompression worry if Lasik surgery is safe.

The Laser and the Deep Blue See

Lasik surgery works like this: A special instrument cuts a thin, circular flap in your cornea. Then the surgeon holds back the flap and uses a laser to reshape your cornea. It's a quick procedure--about 10 or 15 minutes per eye; then the surgeon replaces the flap, which quickly adheres to the eyeball, no stitches necessary. Depending upon individual circumstances, the outcome is often 20/20 vision, though some people may still need corrective lenses or touch-up surgery. There also are potential complications (as with any procedure) that you should discuss with your surgeon. If all goes well, you can resume your normal routine within a week, though you're advised to steer clear of racket and water sports, including scuba, for a month.

All this cornea cutting and shaping leaves some divers with a lot of questions: Can water pressure or interface bubbles on the eye disrupt the flap? Are divers at increased risk for bacteria entering the eye and causing infection? Finally, are they at higher risk for a rupture of the eye from a mask squeeze?Theoretically, all those complications are possible, but the actual risk is very low, especially if you wait at least four weeks before diving. There have been no case reports of dive-related complications since Lasik surgery was approved in the U.S. in 1996. Though it's too early to know if there are any longer-term complications, ophthalmologists are optimistic.

"Lasik surgery has been done worldwide for more than a dozen years without a hint of problems among divers," says Douglas Koch, M.D., ophthalmology professor at the Cullen Eye Institute, Baylor College of Medicine in Houston, Texas. "You equalize in the mask, so divers needn't worry about pressure once the eye heals. I've seen no problems with divers in our practice."It is very important, however, to adhere to the post-surgery advice and stay out of the water for at least four weeks, says Phillip Calenda, M.D., director of Westchester Vision Care in Scarsdale, N.Y. "There are particularly virulent organisms in marine environments that can cause aggressive, nasty infections," he says. Heal first, dive later.

Though Lasik surgery is improving all the time--new "Wavefront" technology that actually maps your eye is making correction more precise--it's still not for everyone. Complications like dry eyes, large pupils or other cornea aberrations can disqualify you as a candidate for surgery.

See Clearly, Flap-Free

For those who can't or prefer not to go under the laser, the FDA recently approved a therapeutic contact lens that corrects your vision while you sleep, so you can see lens-free during the day. This technique, called "corneal refractive therapy" (CRT), works by flattening the surface of the cornea. After a week or two, your cornea's shape is altered similar to the way it would be following surgery, says Teig.

The procedure requires an office visit, where your eyes are mapped, analyzed and fitted for the lenses. There are also follow-up visits to ensure proper progress."It's a great option for divers who are reluctant to get surgery, but don't want to worry about contacts or glasses in the sand, wind and water," says Teig, who uses CRT himself and has already fitted several hundred clients. Unlike Lasik, which isn't recommended for anyone under the age of 18, CRT is fine for kids, as long as they are mature enough to care for lenses.

As with surgical correction, pressure isn't a problem, says Teig. "The pressure isn't great enough to undo the reshaping," he says. You would need to take your lenses on dive trips, however, since the positive effects start to reverse in two or three days if you stop wearing them.Though CRT is currently only approved for nearsightedness, researchers are studying its possible effectiveness for other types of correction. "I don't need my reading glasses anymore since I've been using them," says Teig. "That's exciting, because even surgery can't correct that yet."

To find a surgeon who can perform Lasik near you, check www.lasiksurgery.com. To learn more about corneal refractive therapy, go to www.paragonvision.com.

Contact Lens Cautions

Contact lenses are generally a sound, safe choice for divers. But they're not without risks. Rigid lenses can cause corneal swelling, and soft contacts are susceptible to marine bacterial infection. All kinds of contacts can be lost in the often turbulent scuba environment. For the best results, ask your doctor for a supply of soft disposable lenses. And wear sunglasses to protect your lenses from wind and water.