Antibiotics are effective against trachoma, but old bottles are much easier to come by.
River blindness , caused by a parasitic worm, is currently treated with the drug ivermectin, which only kills young worms, not adults. Ivermectin prevents victims of the disease from becoming blind, but has to be taken until the adult worms die on their own. The International Center for Agricultural Research in the Dry Areas has developed a strain that contains much less of the neurotoxin and can be eaten safely. Of course, distributing it is another matter. The toxin in absinthe has been identified.