Ooh, that's a useful snippet - my lenses are Esilor Forte coated
We get told its at our discretion but as long as the frame doesn't look like its been run over by a bus then they will be happy to replace the lenses. They do have to go back first so you'll have to wear another pair for a few days.
The lenses are plastic so are by no means scratch proof but the coatings are very good and in general use don't get scratch easily.