A team of doctors working with veterinarians at San Diego Zoo have carried out successful cataract surgery on a western lowland gorilla.
An eye surgeon who had operated on thousands of humans but no other type of primate performed the procedure.
Three-year-old Leslie was suffering increasing blindness in her left eye as a possible result of an injury.
Leslie, who weighs 65lb (30kg), is now back with her troop as she recovers from the surgery.
A team of ophthalmologists and anaesthesiologists from the University of California San Diego Health hospital were called to help in the zoo’s first ever gorilla cataract surgery on 10 December, but it was only announced on Monday.
“As veterinarians, we are experts in our species but we are not necessarily specialists in all of the different fields of medicine,” said zoo veterinarian Meredith Clancy.
Cataracts, which cause a lens in the eye to cloud over making it difficult for patients to see, often occur naturally with aging.
But Leslie’s caregivers believe her cataract was caused by a fall while the “youngster was practising her climbing skills or from an overly rambunctious play session with other young gorillas in her troop”.
Doctors used a pharmaceutical muscle blocker to prevent Leslie’s eye from making the slightest movement.
Cataract specialist Dr Chris Heichel used a microscope to remove the clouded lens and replace it with an artificial one.
Dr Heichel says he has performed surgery on humans ranging from one day old to 105 years, but this was his first gorilla.
The anatomical similarities between human and gorilla eyes meant the procedure wasn’t too difficult, said a press release from the zoo.
Speaking to BBC News, Dr Heichel said veterinarians had told him gorillas should not be looked at directly in the eye as that can make them uncomfortable.
“Well that’s going to be a bit tricky,” the eye surgeon said.
Zoo staff also sedated Leslie’s 31-year-old mother, Kokamo, so she would not be distressed by her daughter’s absence during surgery.