What I find really works well is a lens pouch from Optech. However if it gets wet I would remove it when arriving home or wherever staying for a while and dry the head immediately.
But it is easy put over the top. Other lens pouches may work as well.
Rod
Yes Rod, it's the same idea. I also tried various neoprene lens pouches, but couldn't find one the was long enough without also being very wide . I liked the idea of a brightly coloured bag that made it easier to find not if but when I dropped it along the trail or where ever.
You're right about taking it off at home to remove any moisture or condensation.
It really is a matter of shopping around.
K