I haven't actually been bike touring (no bike here and too low of a travel budget) but this same issue applies equally when hiking and then camping which is what I do on my days off.

I wear contacts, am pretty blind without them (functional, but I sure can't enjoy scenery, and what's the point of hiking then?) and when it comes time to set up camp for the night, my hands are almost always dirty and grubby. if not from sweating or grabbing onto rocks or trees on steep slopes, then from getting the tent set up.

Of course I can't spare the water to get them thoroughly clean (middle eastern summers are no joke), which means there's inevitably some crud on my fingers when I take the contacts out and put them back in. This results in them staying kind of dirty permanently, degrading the quality of my vision.

So...any solutions? Only camp near running water? Get glasses (I've thought about it but sunglasses are also a non-optional part of hiking here, plus the expense is an issue)? Anything else?