Phlogiston
(Phlogiston)
2
I use my glasses cleaning fluid and a microfibre cloth.
I reason that if it doesn’t mess up the AR coating on my glasses - so far, so good - then it shouldn’t mess up the AR coating on my flashlight lenses.
One thing that occurs to me: make sure the lens is bone dry before assembling it into a light, or you may end up with corrosion from humidity on places like aluminium reflector coatings.