An orangutan, who was blinded after being shot 104 times with an air rifle, has undergone surgery to restore her sight.

Aan's left eye was removed after it was ruptured when she was showered with pellets in a cruel attack at an oil plantation in Borneo in 2012. After Aan was attacked, vets managed to remove most of the pellets, but 37 had lodged in her head, blinding her BBC News reports.

A British vet has now performed surgery on her right eye in a bid to restore her sight. Veterinarian ophthalmologist, Claudia Hartley, who performed the three-hour surgery, said the procedure could not have gone any better and early signs looked "very promising".

"The surgery went very well, so we're pleased with how it went. I'd like to assess her better tomorrow when she's behaving a bit more normally. She's still quite seepy and keeping the eye shut, so it's difficult to know how much she sees," she explained.

"If we shone a bright light in she would then scrunch her eye up, so I'm pretty sure she can recognise the light. But we can't assess how well she sees food and trees and obstacles and those sort of things, which is the more critical thing that we need to do."

Hartley, 44, volunteered to travel to the Lamandau River wildlife reserve, in Borneo with her team to carry out the operation. She intends to continue monitoring Aan in an enclosure as the anaesthetic wears off and she becomes more active Sky News reports.

The Orangutan Foundation launched an appeal to raise funds for the surgery. Ashley Leiman, director of the foundation, said being able to release Aan would be "absolutely amazing".

"As a blind orangutan, she was going to spend the rest of her life in a cage," she said.

Described as a "clever" primate she will now be kept in an enclosure at the reserve for just three to four more weeks to ensure she continues her post-op medication before being released back into the wild.

Aan, believed to be aged between 10 and 12, captured the hearts of animal lovers following the attack in Borneo five years ago, who have been closely following her recovery.

Around 56,000 orangutans are believed to live in the wild in Borneo. Reproducing on average only once every seven to eight years they are a critically endangered species.