Ants ate away at the eye of a woman receiving treatment for diabetes at a state-run hospital in eastern India, officials say Tuesday.

The patient recovering from a post-surgery infection shrieked for help as the ants attacked her on Sunday night, but nurses told her it was normal to feel pain from the infection.

On Monday, the patient's family saw a gaping hole with swarming ants in it when they lifted the bandage on her left eye.

Authorities of the Sambhunath Hospital in Kolkata say they are investigating the incident.

"It's not uncommon for ants to attack diabetic patients. We have set up a committee to investigate the unfortunate incident," hospital superintendent A. Adhikary says.

Scampering rats and stray cats and dogs sharing bed space with patients are not uncommon sights at India's overcrowded state-run hospitals that are used by millions of poor and middle-class people.