Have a look at CNIB's resources. They may have someone who can help. Their page on Ontario legal assistance for visually impaired: https://cnib.ca/en/ontario-legal-support-and-resources

If that doesn't work, try calling someone at CLEO https://www.cleo.on.ca/. They will likely know who can help, if anyone can.

There's no magic way to do this. If he's overwhelmed, and a sighted person might also well be in these circumstances, then he needs help. If you have money, pay a lawyer to help him. If not, you're probably the only one who cares enough to tip the scales here. Take some days off work, get in a car and go out there.

Not sure what your circumstances are but sometimes if you see a situation that is going to hell and you're the only one who sees what's going on and cares enough to change it, it needs to be you. Otherwise this situation will probably go about as well as you predict.

Best of luck!

Edit: the suggestions to reach out to agencies are great.

Try posting to r/legaladvice?

Usually you can file a request for assistance,I would check the $1 to see what is mandated.

I'm locking this to avoid any giving of legal advice that no one in this subreddit is qualified to provide.

Unfortunately he's screwed, and it's got just about nothing to do with his blindness. The legal system in Ontario hates fathers, and the mother's word is just about always law. Have a couple fully able-bodied relatives going through variations on the same theme and at different stages and it doesn't get a whole lot better. One of them should have full custody of his kids, but because the mother cried poverty and fed social services a bunch of BS he's still trying to argue against, that's not a thing--he gets shared custody instead, and is still on the hook for full child support. Another is paying child support for 4 kids all over 18 who aren't in school because they won't take his word and the mother can't be bothered.

In short, if you can afford a good lawyer, get a good lawyer. Legal aid is amazing, but as you said they don't have the time or probably resources to give it the attention it deserves. He's probably going to lose by virtue of he was born with the wrong equipment. Paying for a good lawyer just gives him a chance to just lose and not be taken completely to the cleaners. Being on social services will help her, but not him.

This may be a long and uphill battle.

I agree with what these guys said. Find a blindness advocacy organization and start from there. Go to a church and ask for help. They like helping. In the US, we have the Salvation Army that might help in a case like this. The worst they can say is no.

Best of luck.