My dad is going blind from DMD and says his doctor says nothing can be done to help him. He just takes a vitamin for better eyesight :::geesh:::: Has anyone treated this or done anything to help someone with this? Even lifestyle tips, whatever.

The is no direct treatment, as yet.

A good diet with adequate vitamins and especially the antioxidants that come from dark green vegetables,
Brocolli, Spinach, sprouts.
If these are hated, there are capsule supplements instead.

Beyond this, the other things that need to be considered involve making visual tasks easier.
Three B's.
Bigger Brighter Bolder.

Bigger:
"I can't see the time on my kitchen clocK"
... Get a bigger clock.
Move the problem, if you can't move the eyesight.
You can get phones with much bigger buttons...
Large print books...

Brighter.
Provided it isn't causing glare, more light is almost always a benefit. An angled spotlight over the shoulder and CLOSE IN can make a very big difference. You don't need to flood the entire room, but get the light where it's needed.

Bolder
High contrast helps.
A watch with black hands on a white face is going to be much easier to see than one with tasteful silver hands on a grey face, or grey LCD numbers.
Contrasting stripes added to the cooker control knobs beats having them nicely colour coordinated and invisible.
Blue tumblers are much easier to spot on a white tablecloth than clear glass ones...
The edge of a sofa is much more easily seen if it Isn't cream-coloured on a cream carpet.

Lastly, sidestep:
If the vision is too bad to get the news through a newspaper, get a good pusbutton radio: get the news through another medium. Similarly, talking watches are available so telling the time is not dependent on being able to see a watchface.
Sometimes the desired task may not require good eyesight, even if that's the way it's been done previously.

These are all work-arounds and second best to restoring good eyesight, but they can add up to a big practical difference.

Best wishes.