Thanks and good luck, my friend.
The bit that you can deal with right now is your father's eyesight. In your shoes, I would get him the best possible medical advice straightaway, to make sure that his eyesight doesn't get any worse and that anything else relating to his diabetes has been brought under control fully before you try to do anything else.
Please have a look at the Report of the MRT case in the link above. It seems that Mrs Thyagarajan had a number of medical problems. I have no idea whether the other problems described stemmed from or were related to her diabetes in some way - I don't know enough about Medicine to be able to judge that.
I hope that reading the MRT report will give you a clear idea about how "DIAC's mind," works, if you like, in cases where someone's medical condition is an issue.