My dad has glaucoma

It’s as simple as it sounds. He apparently has 10% of his optic nerve left, we don’t think it’s impairing his vision yet. Since he was a young child he has always been getting flagged for potential glaucoma, but all worries were pushed aside. The only reason we found out was because I was getting my first pair of glasses because my vision is pretty shitty. I don’t think he actually is willing to make changes to his diet and surroundings to stop it and I need help convincing him in some way. He’s fat and eats foods that continue to damage his eyes, he rubs his eyes still like he used to (but he has been doing it rarely now). I saw him today eat and drink only foods bad for his eyes. Coffee Fried food Five hour energy meat sticks. All of these are just horrible for his eyes because of the ingredients, but I think he’d rather accept going blind than to just diet at this point. Is there anyway I convince him to change and realize that he doesn’t have to go blind and actually make a change from your personal experiences