Thanks to a bottle of Johnnie Walker Black Label whisky, 65-year-old Denis Duthie, a New Zealander, got his eyesight back after he became blind due to several drinks of vodka.

He had a few vodkas from a bottle that his students at the Western Institute of Technology in New Plymouth to celebrate the 50th wedding anniversary of his parents in June. Mr Duthie teaches catering at the institute.

When he got home, everything became black suddenly. Reports said the vodka reacted with his diabetes medication.

"I thought it had got dark and I'd missed out on a bit of time but it was only half past three in the afternoon. I was fumbling around the bedroom for the light switch . . . I'd just gone completely blind," The New Zealand Herald quoted Mr Duthie.

Doctors at the Taranaki Base Hospital believed Mr Duthie had formaldehyde poisoning linked with ingesting methanol, which could be treated through the administration of ethanol, the same type of alcohol in alcohol beverages.

Due to the lack of enough medical ethanol at the hospital, the doctors instead dripped whisky into his stomach through a tube. Mr Duthie woke up five days later and his sight was back.

Because of his experience, Mr Duthie advised fellow diabetics to curtail their drinking or face health risks such as going blind.

It is not just with diabetic medication that vodka and other alcohol beverages are dangerous to mix. A YouTube video shown below says that combining vodka with energy drinks - which is popular among students - is also a dangerous combination.