"Can aged urine be used for eyedrops?"
I really wouldn't advise doing this. Aged urine tends to develop decent amounts of ammonia (which is the real strong pungeant "chemical" smell), which can be very harsh on sensitive skin tissues, possibility even enough to damage them.
I think the best rule to follow is:
Aged urine for external, "normal" skin, hair, nails, skin burns, etc.
Fresh urine for sensitive mucous membranes (nostrils, eyes, lips, ears, etc) and internal use (ingestion).
I've used fresh urine as eyedrops, and in my ears and nose. In the eyes it stung a bit, sort of like strongly chlorinated pool water, but certainly bearable. And it always seemed to leave my eyes feeling more refreshed afterwards. In ears and nose I never had any problems or burning or anything.
As for storing aged urine I don't think there's any real strict way to do it. I haven't seen any mention of refrigerating it but I don't see how it would hurt. The most common tips I've seen are to use a jar lid or something that is "breathable" to some extent... like, poke a hole in the lid, or use a cork, or something like that, so that excess pressure doesn't build up from the ammonia, and also, keep it from sitting in direct sunlight.
Other than that I guess it's pretty straightforward...
Put pee in jar/bottle/whatever, cover lightly (hole in lid, cheesecloth, cork, whatever), let sit for a week or so (like 4-7 days), then use. Or store indefinitely... I had some sitting for months and used it a little while ago on my legs and it seemed fine. The real strong ammonia odor had actually diminished... it just smelled like... animal pee or something... still fairly strong "pee" smell, just without the strong "chemical" smell/sensation of ammonia...
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