Could you suggest good herbal supplements/vitamins that can help dry eyes or improve vision?

Yes: Yes, omega 3 pills or in diet as wild salmon, etc are the best. See my long post about how to help your dry eyes :) http://eyedoc2020.Blogspot.Com/.

None that I know of,: But you might ask the herbalists. Some physicians believe that taking high doses of omega 3 fatty acids. Others swear by flaxseed oil daily (ingested, not in the eyes). It probably doesn't hurt to try some capsules. If you do a trial, give it at least a month before expecting results. Non preserved artificial tears are pretty natural - usually just a hypotonic saline solution.

Yes: Oral omega-3's can help dry eyes. I have many patients that have seen the benefits of them with their symptoms for dry eyes. Evoa dry suppliments, thera tears nutrition is another.