Are Tear Stain Products Safe?

I do not feel that tear stain products that contain an antibiotic (usually tylan or tetracycline) to be harmful.  The level of antibiotic is extremely low when used as directed.  Actually the level is so low that the drug is not acting as an antibiotic but rather it alters the chemical makeup of the tear so that staining does not occur.  There are "natural" tear stain products available and the criticism of products that contain antibiotics is coming primarily from the manufacturers of the "natural" products.  It is important to note that just because a product is labeled "natural" does not necessarily make it better or safer.  I am comfortable with over the counter tear stain products if used correctly.