After whiskey cures blindness for a man poisoned by a drinking too much vodka, doctors have explained why the unlikely medicine worked so well.

The story of the man who was blinded by his vodka broke last week from New Zealand. After the man drank loads of vodka while on diabetes medication, doctors found that whiskey cures his blindness thanks to its ability to stop the body from metabolizing methanol.

Doctors who found 65-year-old Denis Duthie reeking of alcohol realized that he had formaldehyde poisoning, which occurs when the body ingests too much methanol. It can be treated with ethanol, which is found in whiskey.

It was a scary ordeal for the man, the NZ Herald reported.

“I thought it had got dark and I’d missed out on a bit of time but it was only about half-past-three in the afternoon,” Duthie said. “I was fumbling around the bedroom for the light switch but … I’d just gone completely blind. I don’t remember much after I arrived in hospital. I know the doctor told my wife to say goodbye because they didn’t think I’d be coming out again.”

The idea that whiskey cures blindness may seem far-fetched, but Slate noted that it’s a real thing. Really.

Write Forrest Wickam noted:

“If you drink yourself blind, can you really be cured by drinking whiskey? Yes. Methanol poisoning occurs when your body metabolizes dangerous quantities of methanol, resulting in too much acid in the blood. This acid can then damage or kill cells in the optic nerve. However, the body prefers ethanol (regular drinking alcohol) to methanol, so drinking whiskey or other unadulterated liquor can help prevent the body from metabolizing more methanol. No one who suffers from methanol poisoning should self-medicate with whiskey. If you suspect you’ve consumed methanol, you should call poison control immediately. But if you go to the hospital, don’t be surprised if the doctor tries to cure you with a few shots of the hard stuff.”

So thanks to that information, you now know that if you find yourself without sight after drinking too much, whiskey cures blindness.