Re: Fresh or old urine to wash eyes
I think in general any internal use of urine should only be done with fresh urine. Aged urine is great for external use, but it also tends to accumulate a lot of ammonia, which can burn or in larger amounts can even cause tissue damage (to the more sensitive internal tissues like in the mouth, nose, eyes, etc.)
Deotima mentioned using aged urine on the eyelids, but that's probably about as "internal" as I would go with it. Anything beyond that might be asking for trouble... or at least a very uncomfortable experience. :)
I've used fresh urine in my eyes, ears, and nostrils without any problem, but the one time I used aged urine in my nostrils, it burned pretty bad. It was pretty high in ammonia, but that might vary depending on how you store the urine and how often it's exposed to the air or whatever... either way, I would stick with fresh for internal unless you know what you're doing (for example, have knowledge of ammonia and its effects on the body and are willing to risk experimenting with it, or know of a way to store aged urine without accumulating ammonia, and whether or not it's even safe to take internally, aside from the whole ammonia thing)