I have a very good health food store with a knowledgeable owner. If she suggests a certain root or herb, can I use it safely for an eye infection?

No! There are no roots or herbs to treat eye infections. I have heard of some non-medicinal "cures" for eye infections, however the danger is that the infection will get worse and ultimately cause permanent vision loss while waiting for such remedies to be effective. If you think you have an eye infection you should seek an ophthalmologist to help you immediately.
Check this out. Is she a qualified professional? I suggest checking this out with a medical doctor, naturopath or herbalist.
Conjunctivitis. I don't think you should put anything not sterile on your eyes. Pls see the real dr before damaging your delicate eyes.
Not sure. Knowledgeable in what sense? Medical or pharmacy school?Formal education? Be careful!