"Glass" is a pretty general term. I don't think that pure glass has fluorescent properties, but there are thousands of varieties of manufactured glass, containing a wide variety of additives and impurities, some of which may fluoresce. In the case of camera lenses, I suspect any fluorescence may be due to the multiple protective coatings applied to such lenses, rather than to the glass itself. In any case, I have not noticed that this has caused any problems in fluorescence photography. But theoretically it might cause problems during very long exposures. Paul M.