[keane]

The Spectacle Factory recommends, in order, (1) warm water and a microfiber cloth, (2) Zeiss lens wipes, or (3) an ultrasonic bath: https://www.youtube.com/watch?v=m4lJ_5Tg9Ms

They recommend (v=5FUUgO95sb4) against both detergent for the sake of the lens coatings and against sprays which may cause grease to accumulate around the lens rim.

[OneLeggedCat]

If you're the kind of person who has bought a dozen pairs of cheap Zenni's... the lens coating gets visibly damaged every time I've used hand soap on them. I now just blast them with hot water and wipe dry with a lens cloth. I don't know whether hand soap is a problem for more expensive brands, but it definitely is for Zenni's.