I'm looking for artificial tears. They have to be preservative-free and therefore come in vials that you throw away after one day.

A bit like this: www.usaeyes.org/images/lasik-eye-drop.jpg

I've tried 润洁 from 一心堂, but that's not quite it. Any ideas?

Why not use onions?

Get them at Kunming Eye Hospital at the pharmacy situated to the left of reception. They had ' Systane' when I checked three weeks ago. I use them to treat a Pterygium.