Can someone fucking explain this to me?

I helped my dad sign up for disability because he completely lost his eyesight. We went to several eye doctors and specialists and nobody could help him so he can’t fucking work because he literally cannot see at all anymore. I sent all the paperwork in and proof that we went to specialists who couldn’t do anything for him and we just got the notice that he’s been denied disability. 

I’m filing an appeal but can someone please explain what the fuck reason he did not qualify?