Here's the thing. The problem with a legally blind person (who may be able to see but just not read road signs) having a gun is they can't shoot straight enough for it to be safe, yes?
But a gun is not inherently safe. It's a lethal weapon for fuck's sake. Trying to make gun use "safe" is like trying to fly a plane without tilting it. Sure, it feels better to the central nervous system of people who are afraid of flying. But you're not going to get off the ground.
People are required to go to classes for gun safety in some places. Should they also be required to pass a marksmanship test and if so, how strict should the standards be? Because if you don't require a marksmanship test for every gun owner, I don't see how you can specifically forbid legally blind people. What about people with arthritis? With any number of conditions that can cause the hand to shake? What about the fact that under stress, marksmanship goes through the floor anyway?