General Discussion - Healthy liver and eyes

Two days ago while on a trip to Hanzhou I found myself in need of some saline solution for my contact lenses. My friend, a native of Shanghai, helped me find my way to a store that might have what I needed.

Some of the "Chinglish" phrases were quite awkward to me as a non-Chinese reader. But one phrase stood out in particular. To paraphrase, it said that it promoted clear eyes by way of a "healthy liver".

I questioned my friend about it but she simply said it is an old expression and would elaborate. Now I'm dying to know.

Can you help me put this medical mystery to rest?