Hi, This is a trodden path but here goes...
Research came out in 2003 in a well-known Journal by: Quaranta L., Bettelli S., Uva M. G., Semeraro F., Turano R. and Gandolfo E. (2003): Effect of Ginkgo biloba extract on preexisting visual field damage in normal tension glaucoma. Ophthalmology. 110(2): 359-62; discussion 362-4.
This was, apparently, a proper scientific study showing that ginkgo b. improved glaucoma symptoms. Normally a double-blind, crossover type of study is pretty much *proof* of an effect except where *concerns* exist. Concerns might be - falsified results, special (hidden) ingredients in medications, or something else quite unexpected. In this case it all looked good. I don't know anything about the reputation of the researchers, but the only other thing was the low number of subjects in the tests. I think it was 27 ppl - now if it had 100 or 1000, that would add a lot more weight. So there's a chance the result just turned out this way. (Throw up a coin and it lands on its edge.) Of course proper research (like this work) uses statistics to rule this out so the probability might have been 1 in 1000 that it was simply a fluke result.
They did use a purified form of ginkgo b. and I found that was not easily obtained. And they used pretty decent doses.
Okay, that was 2003, and in 2005 a patent appeared for the US (also, I think world-wide). It was by Prof Robert Ritch, perhaps the most eminent ophthalmologist in the US. Patent US 2005/0163873 A1. See this guy's C.V.! He was patenting this very same treatment. So you have to ask why, after publication of pretty clear-cut benefits from ginkgo b. is such a prominent scientist patenting the treatment? He must have thought it was something that worked. Now usually Professors have teams of students just waiting for ideas to work on so possibly (probably) he did his own follow-up work. He must have. Anyway I have never tried to contact him to find out what research they did or what results they got. Nothing I know of has been published and Prof Ritch has published 100's of research papers.
I have tried to contact the original researcher (Quaranta L.) but my emails were never answered. Usually for such work there would be other unpublished "backup" work, field trials, etc. But I found nothing.
It would be useful to get a response from Prof Ritch on this - he would know I'm sure. Whether he would reply to your email is anyone's guess. Might be worth trying his university department and try to chat with one of his student researchers - a door in that way would be my approach.
You'll find abstracts of the paper around but I don't think I ever found a PDF.
I have a copy of the entire paper here but could not find it yesterday. I think I might have got a print-off from the Journal in the Univ. library. Anyway if you still want to read the full text just email me and I'll have another look.
My experience. Well, I tried two forms of ginko b. - Swansons and Dr's Best extra strength. I can't test for say a 10 or 20% improvement so it's had to tell but nothing dramatic occurred that I could detect. However, ginkgo tended to give me a headache so in the end I cut it out.
Other work- well see this review article, "Ginkgo - Herb Monograph for Health Professionals" also discusses a benefit in here:
Evans J.R. (2004): Ginkgo biloba extract for age-related macular degeneration (Cochrane Review): The Cochrane
Library. Chichester, U.K., John Wiley & Sons, Ltd., pp 10.
Hope this helps, and if you find out anything please post it back here - even if Prof Ritch says it "never worked".
Cheers for now.