I repeat what I wrote above: using a saline solution stored in a "large" container over a long period of time, only to put a few drops in your eyes every now and then, is asking for trouble. I don't know the US pharmaceuticals, but if you lived in Europe I'd first have a check-up with an ophthalmologist and ask him to prescribe you "artificial tears": they're also saline solutions but over here in Europe they're sold in small containers of a few drops each, thus no risk for infection. More expensive than the saline solutions you mention, of course, but after all it's your eyes. No charge for this piece of advice...