Here's the punchline
One interesting wrinkle in the data is glaucoma, for which there was a small increase in demand for traditional drugs in medical-marijuana states. It's routinely listed as an approved condition under medical-marijuana laws, and studies have shown that marijuana provides some degree of temporary relief for its symptoms.
The Bradfords hypothesize that the short duration of the glaucoma relief provided by marijuana — roughly an hour or so — may actually stimulate more demand in traditional glaucoma medications. Glaucoma patients may experience some short-term relief from marijuana, which may prompt them to seek other, robust treatment options from their doctors.