This is a great tip, we all need reminding so it doesn't happen 'the hard way'. I almost always wear sunglasses in the garden, but in summer I go out in the cool, breezy evenings when they really aren't needed for sun protection.
My favorite new garden toy is a rechargeable leaf blower, and of course it blows all sorts of stuff in all directions so the other evening I came in with an eyeful of gritty something. Lucky it wasn't worse, it all washed out with no ill effects. My sunglasses were on top of my head the whole time, so it served me right!