re: the vision test requirement in DC.....
The guy that gave me my Concealed Carry class, Paul Horvick, of ShootingSafely.com, related how he had, under threat of an ADA lawsuit, repeatedly given ( and eventually passed! ) a blind, wheelchair bound man the required CCW class for Minnestota, complete with range qualification.
"Equality Before the Law" .... either it means something, or it does not.
TheGolden Rule of Tool Use: "If you don't know what you are doing, DON'T."