Hello Paul,
I just got glasses a couple of months ago. They have anti-reflection coated plastic lenses. I was instructed to be careful in their cleaning because they can get scratched. I am to avoid using paper towels and toilet paper (because they contain wood particles that can scratch the lens) and to use cotton or microfiber towels. The most important step in cleaning is to first rinse off the dust on the lens. This avoids grinding it into the surface of the lens. I have a alcohol/water based lens cleaner (from LensCrafters) that I use, and I just rinse them off with water. Water alone will work, but it is not real good for oil or grease.
Tom