In Michigan, if ballot question passes could I smoke a joint for my glaucoma?

When I read this story in today's Detroit News, I was reminded that I and the rest of Michigan voters will decide whether marijuana can be legalized for medical reasons.  And I would qualify. 

I have had chronic open-angle glaucoma for several years and supposedly it would lower the pressure inside my eyes. 

The story says that polls indicate that the proposition would pass pretty overwhelmingly. 

My gut reaction is that I'm against it.  Even if it's legalized in Michigan, it's against federal law. It also seems like a first step to legalize grass for everybody.

By the way, does anybody know how much it lowers pressure in the eye?