I am a staunch believer in doing all you can, but I agree with this wholeheartedly. This is very well stated.(forgive me if you dont need this pep talk, but I'd rather tell someone who doesnt need to hear it than not tell someone who does)
I dont know your personal opinions on the matter, but.. if it is going to be lifelong, it is okay for you to decide to cull the bird. that level of supportive care (cleaning eye multiple times a day) is more than anyone expects of you & no one would fault you for putting the bird down.