About 29 patients hailing from Kanduvanur village lost their vision, of which nine of them lost their eyesight forever.
The camp was organised by an eye hospital in the locality.
MRK Paneerselvam, Health Minister of Tamil Nadu said, "Last month on 29th a free eye camp surgery was organised by the hospital. According to our account 29 people underwent the surgery."
"Twenty of these people will get back their vision but nine people lost their eyesight," said Paneerselvam, and added, "Our medical team is conducting an enquiry and after the reports we will take necessary action against the hospital administration."
The patients have lodged a complaint against the hospital administration.
The protestors broke the lock and entered into the hospital and damaged property after the incident.