Along a Pacific atoll, frogmen are swimming past kaleidoscopic schools of fish, undulating plants and spiky sea urchins in search of a drab white boulder made of coral. It's a medical find: the ideal material for an artificial eye.
In an operating room in Baltimore, Dr. Darab Hormozi is implanting a coral ball into a patient blinded in one eye by a nail. Once six muscles are surgically attached, the fake eye will move in tandem with the real one -- even though it can't see a thing.
But the implant won't look real until John J. Kelley Jr., a member of the small fraternity of artisans called ocularists, adds a plastic facade that has all the right aesthetic details -- flecked iris, milky white sclera, even the spidery blood vessels that creep along the margins.
Once that's done, you'll think the prosthesis is looking right through you.
For hundreds of years, European and American craftsmen and scientists tried in vain to fashion an artificial eye that looks and moves like the real thing. The first implant was blown glass. Further attempts were made with silk, wood, cork, gold, aluminum, rubber, sponge, silicone and steel.
The eyes were fine in some respects. They filled the socket, preventing the bony orbit from closing in on itself. Skilled craftsmen, adept with paints and techniques of glass blowing, could give them a natural look. But they were missing something.
They would move, but in a floating, disembodied fashion that would draw unwanted curiosity. In recent years, ophthalmologists have caught on to the wonders of coral -- a material that, because of its microscopic pores and uncanny resemblance to human bone, can be made to move like a puppet on a string.
It can dart from side to side or make wide, sweeping rolls. But Dr. Hormozi, a Baltimore ophthalmologist who has implanted 80 coral balls over the last three years, seems equally impressed with the way the eye shifts almost imperceptibly when someone looks at a stationary object.
"You get that targeting motion that is characteristic of the living eye rather than the dead motion of the dead eye," said Dr. Hormozi, a specialist in ocular plastic surgery at the Greater Baltimore Medical Center and St. Agnes Hospital.
"If you're looking in someone's eye and the eye looks funny, you're not making eye contact. And if you avoid looking at someone's eye, you lose the power of conversation."
Someone who lost an eye in an accident may want a prosthetic eye. So, too, may the person who had an eye surgically removed because of illness, infection or a congenital deformity.
Timothy Prechtel, 22, of Edgemere, had his right eye removed last year because of a painful condition dating to childhood. His problem began when a young playmate tossed a nail that found his eye.
Surgery restored his sight, but a lingering pain grew so intense that doctors eventually had to deaden all sensation -- including sight -- with a chemical injection when he was 13.
Last year at GBMC, Dr. Hormozi removed the eye when it became infected and replaced it with a coral ball. "The old eye was shriveled up, dying," said Mr. Prechtel, a technician for Bethlehem Steel.
A convincing look
For at least a century -- long before coral entered the picture -- the artificial eye has been a two-part device.
The foundation is a ball that's implanted deep in the eye cavity. It is sealed from the outside world inside a tough sac known as sclera, the same tissue that gives the natural eye its "white" on either side of the iris.
If surgeons can't salvage the sclera from the patient's original eye, they obtain it from an eye bank -- a repository of donated tissues used for transplant. Sealing the implant prevents transmission of germs from the environment into the eye cavity.
To give the device a convincing look, ocularists fashion a shell that hugs the sphere the way a contact lens hugs a living eye. The shell -- made for many years of glass, but since the 1940s made of plastic -- is what gives the artificial eye the look of anatomical correctness.
Dr. Arthur Perry, a San Diego ophthalmologist who invented the coral ball, said he was troubled by the artificial eye's immobility when he began seeing patients as a young resident in the mid-1970s.
"People would come in -- their eye would look great, but as soon as they'd move the good eye on the other side, their implant wouldn't look right," he said.
This posed a scientific challenge -- a maddening one.
In most cases, the patient with a blind eye on one side and a seeing eye on the other had functioning muscles in both sockets. The "good" eye supplied the brain with all the visual information it needed to trigger muscles movement in both eyes -- even if the other eye saw nothing.
So when surgeons removed the blind eye, they were left with muscles that were theoretically capable of moving an implant. But the muscles, like the implant itself, had to be sealed inside tissue to prevent infection -- leaving surgeons helpless to bring motion to the outer shell.
They compromised, strapping the muscles around the implant like rubber bands around a ball. The muscles would move the implant, but not the shell to any great degree because they lacked a connection to the outside. Sometimes, the muscles would provide enough friction to nudge the shell one way or another -- but unconvincingly.
Dr. Perry figured that the answer was to peg the shell to the ball. Although logical, the approach had been tried many times, with miserable results. To sink a peg into the implant, surgeons had to drill a hole through living tissue. Germs would quickly invade the hole and the eye socket would become infected.
In the mid-1980s, Dr. Perry had a brainstorm. He became aware of a California company, Interpore International, that was using two varieties of sea coral to make grafts for dental implants, facial reconstructions and other orthopedic procedures. Maybe, he reasoned, coral would provide the right material for a pegged implant.
He was right. Experimenting with rabbits at the University of California-Irvine, he noticed that blood vessels from the surrounding eye cavity would crawl through the coral's interconnected pores.
Coral -- just a skeleton laid down by tiny sea animals -- acted like a sponge once placed inside the human body.
Most important, a film of living tissue would line the pegging hole once it was drilled, and this provided an excellent barrier against infection. The film would not grow without nutrition supplied by blood.
"The interconnected pores are really the key feature," said Dr. Edwin Schors, research-and-development vice president at Interpore, which harvests the coral, chemically treats it, and shapes it into balls.
There are between 300 and 400 broad categories of coral, but only one lends itself to the artificial eye.
Goniopora, a variety that grows along the equator in the Pacific and Indian oceans, has interconnected pores about a half-millimeter wide, just the right labyrinth for blood vessels. It grows in large, round formations from which several eye-sized balls can be carved.
Interpore hires snorkelers, who search out the corals, tie ropes around the rounded heads and hoist them out of the sea. In the laboratory, the coral is converted from calcium carbonate into calcium phosphate -- the same material as bone. As a result, blood vessels recognize the implant as native to the human body.
A second company, Integrated Orbital Implants Inc., of San Diego, markets coral balls in four sizes. About 5,000 are sold each year, said Dr. Perry. The balls cost about $700 each -- but the cost of an artificial eye reaches $7,000 when surgical, ocularist and hospital fees are tallied.
The coral ball is usually used to make a person's first artificial eye. But it also can replace an old, immobile eye as long as the muscles are functional. In either case, the implant looks sunken and featureless until it is covered with a plastic shell endowed with the aesthetic details of the natural eye.
The demand for artificial eyes, although steady, is not large enough to support more than about 100 ocularists across the country. Baltimore has two. Large cities may have a few more, and small towns none at all.
In his eighth-floor office on Read Street, ocularist John Kelley dabbed oil colors onto a plastic circle that would become the iris. He'd occasionally look into Mr. Prechtel's good eye, noting that the iris was dark gray on the rim and light green around the pupil. In between were a series of transitional colors that were neither gray nor green.
"People ask me all the time to tell them what color eyes they've got," Mr. Kelley said. "Well, you might have burnt sienna, burnt umbra and gray and yellow. What color is it?"
Mr. Kelley painted against a dark plastic, which made his work look muddy until he held it to the natural light streaming through his window. Suddenly, the iris came alive with a burst of subtle hues.
A lifelike appearance
For the eye's pupil, he added a black plastic dot. Then he bonded the disk to a milky-white shell made from a mold of the patient's eye socket. He was almost there. With tweezers, he lifted a red thread from a dish, held it over the plastic sclera, and laid it down in a squiggle. He laid down another, and another.
These fake blood vessels gave the "white" a lifelike appearance.
Then he bonded a clear white lens to his handiwork. It magnified the eye and gave it the illusion of depth.
"I grew up with this," said Mr. Kelley. He learned the trade from his father, John, a Philadelphia ocularist who also taught his other son, Kevin.
Once the finished shell was pegged to Mr. Prechtel's implant, the real and artificial eyes looked practically identical. They moved together, and their colors matched to the smallest fleck. If there was a flaw, it was that the false eye fell millimeters short of the corners when Mr. Prechtel looked to one side.
"I'm just so happy that he looks like he does," said his mother, Janet. "I'm an eye watcher, and it's great to look at him now."