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Young owl flies to freedom with new set of eyes

Watch out, mice: Minerva can see clearly now

By Marsha Walton

Ready for my closeup: Minerva's sight is back to normal after cataracts removal and lens implants.
Cool Science
University of Wisconsin

(CNN) -- A great horned owl named Minerva is making history in the treetops of eastern Wisconsin. At least, her eyes are. Veterinarians say she's the only animal in the world, in the wild, with surgically implanted artificial lenses.

The bird with a new lens on life has a lot of humans to thank for her newfound health.

Last December, Renee Prausa called veterinarian Dr. Chris Katz in Two Rivers, Wisconsin, to ask if it was normal for an owl to sit on a fence for three days, without moving.

Katz told her that kind of lethargy was a real danger sign, especially in such a cold climate. He told her to call the rescue group, Wildlife of Wisconsin, or WOW, immediately.

"She was so weak and dehydrated we had to put a tube into her stomach," said Susan Theys, who works as a full-time volunteer for the rescue organization.

Dr. Katz later examined the bird, and even in its weakened state, he said she showed some spunk.

"They are not timid animals," said Katz. "Even though she couldn't see us very well, she was really using her talons, we had to be careful," he said.

Other than her weakness from malnutrition, X-rays and a thorough exam didn't reveal any other health problems.

Katz and veterinary ophthalmologists Samuel Vainisi and Gretchen Schmidt confirmed that the owl had cataracts in both eyes, which had prevented her from seeing and catching prey.

Because the bird was only about a year old, and otherwise healthy, the doctors and the WOW volunteers decided to go the distance to try to rehabilitate this feisty bird.

'A really tough bird'

When the bird was stable, her next stop was the University of Wisconsin Veterinary School in Madison.

The staff there named her Minerva, after the ancient goddess of war and wisdom.

"She's a really tough bird, she fit both the 'war and wisdom' descriptions," said Dr. Renee Carter, a resident in veterinary ophthalmology.

Dr. Chris Murphy, professor of ophthalmology at the veterinary school, led the surgical team in the four-hour procedure to remove both cataracts, and to implant artificial lenses so the owl could again see things in focus.

While Murphy and his colleagues primarily treat the eyes of domestic animals, they have also done procedures on wild and zoo animals

"Armed with the right information, humans can design, fabricate, and implant artificial lenses on any animal," said Murphy.

Minerva did not even have to wait for her lenses to be made: Murphy had a pair of custom lenses that had been created for another great horned owl six years ago. They were not used then because the bird had other problems that prevented the eye surgery.

Murphy says an owl's eyes are much different from a human's, because they've adapted for nocturnal hunting.

"There's a big pupil, and a big cornea to collect a lot of light," said Murphy. "Even though owls only weigh about two kilograms (4.4 pounds) their eyes are significantly bigger than a human's," he said.

Returning to the wild

Jerry Theys releases Minerva after her recovery from eye surgery.

Drs. Murphy, Carter, and Katie Diehl donated their services for the surgery. Wildlife of Wisconsin paid $300 for anesthesia and other drugs.

Carter says the experience with this owl will help in understanding and designing lenses for other birds, possibly endangered species such as condors and eagles.

After her eyes healed and Minerva proved she could see and catch live prey in a confined area, it was time to let her go. She was fitted with a radio transmitter so her movements could be tracked, and released April 30 at the same place where she had been rescued.

Wildlife of Wisconsin rescues hundreds of animals each year, but the group's volunteers had a special attachment to Minerva.

"It's always gratifying to release an animal," said WOW's Jerry Theys. "This one may be special because it took a lot of people to get this bird on her way," he said.

And about her disposition?

"We've had quite a few great horned owls," said Theys. "This is by far the orneriest great horned owl we've had," he laughed.

WOW will continue to monitor Minerva's moves for the next few months.

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