3 elderly king penguins needed cataract surgery and custom lenses. Vets in Singapore swooped in to help.

• Old king penguins in Singapore had trouble seeing things in front of them.
• They were given cataract surgery and fitted with custom lenses from Germany.

When a group of three king penguins and three Humboldt penguins from Singapore's Jurong Bird Park developed cataracts and started having difficulty seeing things in front of them, vets swooped in to help.

The elderly penguins had cataract surgery in December, during which vets removed the cloudy lenses caused by cataracts, Singapore's Mandai Wildlife Group said in a statement to Insider.

"We noticed the cloudiness in their lens and moving about like they were having difficulty seeing things in front of them," said Ellen Rasidi, a vet with the Mandai Wildlife Group.

The surgeries were a little more complicated for the king penguins, who were all more than 20 years old. They were fitted with lenses from Germany that took two months to make.

These lenses were custom-fitted to fit each penguin's eyes, per the statement.

"The success of these surgeries marks a milestone in veterinary medicine. While intraocular lens implants are common for humans and some domestic mammals, it is likely the first time they have been successfully used on penguins", said Gladys Boo, the veterinary ophthalmologist who led the surgeries.

"As a larger species, the king penguins have eyes large and stable enough to hold the custom lenses in place, so we decided to pursue this world-first procedure to further improve their vision above removing the cataract," she said.

The procedure was made more challenging because penguins have three eyelids, said Boo. This third eyelid protects penguins' eyes underwater.

"The third eyelid tends to close during the surgery which can make it difficult for us to access the eye. I'm glad we were able to work through these challenges to improve the lives of these animals," she added.

The Mandai Wildlife Group did not reveal the cost of the custom-fitted lenses.

The penguins had to stay out of the water until they recovered. They were also given eye drops twice daily to help with their recovery.

All six penguins have since recovered fully, showing an "increase in responsiveness and activity levels," which indicate that their vision has improved, said Rasidi. They have now returned to their colonies.