Cataract surgery gives turtle sight

July 18, 1994|By Michael James | Michael James,Sun Staff Writer

It's one for the medical textbooks -- a 93-pound sea turtle that couldn't see, but whose sight was saved by cataract surgery.

The loggerhead turtle still is recovering and could use a pair of spectacles.

A team of ophthalmologists -- an animal eye doctor and a human eye doctor -- performed successful surgery on the turtle June 11 at the National Aquarium in Baltimore to give it a fighting chance to return to the wild.

Aquarium officials said they believe it was the first time a sea turtle had undergone surgery for cataracts.

"A lot of people are familiar with cataracts as something that occurs in old people. But that's not the case here. This is a young turtle," said Dr. Brent R. Whitaker, the aquarium's director of animal health.

"We've removed the cataracts because we feel that will provide the animal with its best shot for survival in the wild. It's got a good chance of making it," Dr. Whitaker said, watching as the turtle gobbled down crabs and fish in an aquarium pool.

Aquarium doctors hope that the animal, which has regained its sight and can now see its food, will be released by the end of the month. Its vision is cloudy, but appears to be functional enough for it to survive, the doctors said.

The turtle, believed to be about 15 years old -- so young by turtle standards that its gender isn't determined yet -- was found Oct. 23 by a fisherman in Virginia Beach's Rudee Inlet.

With fish hooks in its neck and bilateral cataracts in both eyes -- possibly caused by an infectious disease -- the turtle was emaciated and floating helplessly in the water. The animal, which weighed 78 pounds, was taken to the Virginia Institute of Marine Science and was diagnosed as virtually blind. At best, it could differentiate between light and dark, but couldn't see shapes.

On Dec. 14, the turtle was transferred to the National Aquarium, where a team of doctors was assembled to plan for eye surgery.

Loggerhead turtles -- which can live to be 50 or more years old and can weigh up to 300 pounds -- are classified as a threatened species. They depend on their eyesight for tracking food, but, even more important, they need it to avoid such dangers as fishing nets and boats.

"How much these animals rely on sight is a question we really can't know for sure," Dr. Whitaker said. "Let's say their sense of smell was keen and it can lead them to fish. But if those fish are in a net, they need their eyes to sense the danger."

A cataract is a clouding of the lens that creates blurry vision. If LTC the clouding is severe enough, sight can be lost until the cataract is removed.

The surgery on the turtle was performed by a veterinarian ophthalmologist, Dr. Kelly Corcoran of the Animal Eye Clinic, who operated on one of the turtle's eyes, and Dr. Gregory Ogawa of the Johns Hopkins Wilmer Eye Institute, who removed the cataract from the other eye.

As a guide, the two doctors used medical illustrations drawn from the head of another turtle that was recently killed. Johns Hopkins medical student Laura Williams provided the drawings, the first ever detailing the inner parts of a turtle eye, aquarium officials said.

Drs. Ogawa and Corcoran, who volunteered their time and equipment for the operation, were both out of town and couldn't be reached. But Dr. Whitaker said the operation went more easily than expected.

With a special tool, the doctors removed the damaged lenses of the turtle's eyes and used very fine sutures to seal the corneas. Without the lenses, the turtle won't be able to focus well on shapes, "but before, the lenses were completely useless. He wasn't getting any images at all," Dr. Whitaker said.

Perhaps the most worrisome part of the operation was the anesthesia injection, Dr. Whitaker said. Because of the turtle's extremely slow metabolism, it took the animal nearly 2 1/2 -hours to wake up.

Although the turtle doesn't have a name -- aquarium officials try to discourage naming rescued animals because they don't want them viewed as pets -- it does have a comfortable home for now. And, it has gained 15 pounds since its arrival in Baltimore and seems to have regained its strength, according to the aquarium staff.

Soon it will be moved into a larger pool at the aquarium, and its reactions and senses will be closely watched. If it continues to show improvement and is able to swim toward food and catch it, it will one day be released back into the coastal waters off Virginia Beach.

"It was the humane thing to do," Dr. Whitaker said of the surgical effort. "The animal was in trouble, and we had the chance to help it -- and along the way, we learned something about sea turtles and how they see their world."

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