Only after the second cataract operation on C’sar the elephant’s gargantuan eyes did the veterinarians at the N.C. Zoo decide that maybe, just maybe, the idea wasn’t so crazy after all: Contact lenses for an elephant.
Big ones, of course.
After all, C’sar, a 38-year-old African bull elephant, weighs about 12,000 pounds and sports a pair of peepers nearly as big around as racquetballs. He was the zoo’s first elephant, and his hulking form has been a mainstay there since 1978.
It was in 2010 that zookeepers first noticed something white in his eyes. Experts from N.C. State University’s College of Veterinary Medicine were called in. Yep, cataracts, they said.
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At first, the thickening clouds in his eyes didn’t seem to bother C’sar, even when those in his right eye grew dense enough to block most of the light, said Dr. Ryan DeVoe, the zoo’s senior veterinarian.
It was only when the one in the left got serious, too, that zoo staff noticed an alarming change in C’sar. When he tried to move, he would stub his toe, or bang a tusk into something. Eventually he turned lethargic, seeming to give up, and mostly just stood around in a corner, leaning on a wall and whiling away his days. C’sar was pulled from exhibition for his own safety.
C’sar’s behavior was troubling, DeVoe said, particularly so in an elephant, since the species is highly intelligent and, with its trunk, should be able to feel its way around at least some.
It wasn’t long before C’sar went from lean, muscular and healthy to thin and wasting away.
If it continued, DeVoe said, the zoo probably would have had to euthanize C’sar.
“We were just frantic, thinking that it was probably something else in addition to his vision, because the changes were so dramatic,” he said. “But we knew that we had to at least fix his eye, because we knew for sure that was a problem.”
The only way to treat cataracts is to remove them. So last November, Richard McMullen, an assistant professor of ophthalmology at the NCSU vet college, drove to Asheboro. When the patient weighs six tons, it’s easier to go to him.
There, assisted by a team that also included zoo veterinarians and keepers, McMullen removed the cataract from C’sar’s left eye.
The improvement was almost as startling as the elephant’s decline, said DeVoe. He suddenly quit bumping into things, was able to find snacks of cut-up vegetables the keepers would stash around his pen and was able to return to his sprawling exhibition habitat, the Watana Grasslands Reserve.
Then, on May 31, McMullen returned and removed the cataract from C’sar’s other eye.
The zoo staff had expected only a modest difference, if any. Instead, C’sar made another big improvement, becoming even more mobile and more engaged with his world and his keepers.
“It was dramatically different, and he seems to be in pretty good shape now,” DeVoe said “He’s noticeably brighter, and more interactive and he just moves around differently.”
The unexpected second jump in C’sar’s quality of life cuts to the heart of a basic difficulty in dealing with vision problems in animals, particularly those short of complete blindness: animals can’t tell veterinarians they’re having trouble seeing, so vets must interpret their behavior.
“The hardest part is accurately and qualitatively determining what effects vision defects have, because we can’t just ask them,” McMullen said. “We have to get it indirectly from behavioral clues.”
Though he couldn’t ask C’sar to cover one eye and read a chart on the wall, McMullen was able to use a machine to test his vision. It beams a light through a test lens into the eye, bounces it off the retina and back through the lens. By moving the light and observing how it reacts, he said, he can come up with something that’s pretty close.
Operations leave him farsighted
The cataract operations left C’sar farsighted. The veterinarians know that because he is missing his natural lenses now.
They had wanted to implant permanent prosthetic lenses to replace them, McMullen said, but the structure of C’sar’s eye wasn’t strong enough.
They decided that it was probably at least worth trying contacts. Now a company is making a pair for C’sar, and the veterinarians are thinking that perhaps by early fall his eyes will be fully healed, and they and C’sar’s keepers will try out the idea.
Contact lenses have been used on an elephant before, but only for a few days to protect an eye while it heals, a technique sometimes used on dogs.
DeVoe said the vets believe this would be the first time contacts had been used to correct vision. They’re not sure it will work.
Elephants are smart, and can be trained to accept procedures that help them. For example, keepers trained C’sar for weeks before his cataract surgery by holding a water-filled glove against his eye so that he would be ready for the examinations.
But even though the lens will be soft, it also will be large, with a bubble shape to fit over the entire surface of the eye. It will be held in place by one of the elephant’s three eyelids.
DeVoe and McMullen said that the contact lens may be too irritating once it’s in place, or too troublesome to get in and out. It’s key that it not require frequent removal for cleaning or other reasons, DeVoe said. The hope is that it will be able to stay in place for months at a time, with routine monitoring.
It’s particularly important, McMullen said, that the keepers handling C’sar’s eye care have a say in whether the idea is working.
Impact for other animals
McMullen performs research on animal vision problems and is keenly interested in the idea of corrective contact lenses. He is excited about the idea of using anything learned from C’sar to explore the idea of contacts for other species, such as horses and dogs, which he works with the most.
But both he and DeVoe said that they’re not interested in pursuing the experiment if it doesn’t seem likely it will improve C’sar’s quality of life, and do so to a degree that outweighs the difficulties involved for C’sar and his caretakers.
Working with the bright, curious and highly trainable C’sar, McMullen said, was one of the greatest experiences of his life.
DeVoe said that exploring the mysteries of the elephant’s sight – and seeing life-saving improvements – has been particularly rewarding, and the contacts may add another valuable lesson.
“I’ve learned so much from this case,” DeVoe said.
“My gut says that there won’t be a dramatic improvement with contacts, but if you had asked me before the second surgery, I’d have said the same thing,” he said. “We have seen unexpected results so far, and it could happen again.”