What blinded them is the same thing that blinds us. They had an idea of who Jesus was supposed to be. They had formed Him in their minds in their own image and likeness. Yet their image and ours put limits on the man who is, God. So, when this man appears to them in the garden and on the road they do not recognize Him. He doesn't fit the image they had formed. He far exceeds it and it makes them, in a way, blind and deaf, if only for a time.
The two disciples don't recognize Him until the breaking of the bread. Many commentators say that they saw the wounds in His hands at that time and they knew it was the Lord. I would argue that it may have been the wounds but it was probably more the words. Perhaps His words were once again, "This is my body which is given for you. Do this in remembrance of me."
Whether it was the words of Our Lord or His physical appearance we do not know for sure. What we do have is a record of the reaction of the two men, "...they rose that same hour and returned to Jerusalem..." The seven mile walk from Jerusalem to Emmaus became a seven mile jog from Emmaus to Jerusalem - on that same day! The reaction was to run and tell others. Mary Magdalene too ran, at the Lord's command, to tell others.
So, do you and I walk around kicking stones like the men on the road to Emmaus or are we like the men on the road back to Jerusalem? He has risen indeed! Let us run to everyone crying out, "I have seen the Lord!"