I know I have replied before, but I have more information from the Bible to share on this topic.
If you have a Bible read Job 34: 10.
God is never the cause of our suffering. Rather , suffering comes from the Devil, from humans who make bad choices, and sometimes from being in the wrong place at the wrong time. When we suffer, God is there to support us. He really cares about us.
I understand that what I'm going to say doesn't apply to all blind in general, but is a blind man is reading this topic, please tell us about it. (uh?)
Suffering might have a "purpose", which means, it is between us as part of our lives. I don't think that suffering is caused by the Devil, or from us because we commit sins, or because bad luck, or whatever.
There is the story of the dude born blind. According to others around him, it was because one of the parents committed sins, etc., but Jesus said no, that the poor fellow was born blind for the glory of God. And later Jesus performed a miracle.
Of course, this is one case alone, we don't see Jesuses around returning back the vision to blind dudes. But their suffering of being blind, because they lack of this essential sense of sight, is not because someone did something wrong or, because the Devil caused it.