Medical discharge in WW2

[zimsbaby]

Hi

Not sure if anyone can help, but I'm trying to find a list of valid grounds for medical discharge from the forces during WW2?  i.e. conscription was in force unless you were in a reserved occupation (scientist, farmer etc) or unless you had a specified medical condition. 

As the war went on did the officials start to turn a blind eye (no pun intended!!) to some of these medical conditions in order to get more people signed up?

Any info would be appreciated!

thanks,
zimsbaby