Of course you don't want your son to go blind. I totally understand your actions if he is really deliberately putting it off. However, I'm assuming he's an adult (at least over 18)? If so, in the end all you can do is tell yourself that you tried to help him. If he does let his eyesight go totally bad, it's his fault. I assume he's not intellectually impaired? I will say that my adult nephew has a pretty bad case of ADHD (inattentive type) but he was very motivated to have a neurological issue looked into. So, I don't think having ADHD, itself, makes people not take health issues seriously. If the situation is making him mentally ill, perhaps it might be depression (and not the ADHD itself) affecting his actions or inaction.