Snakes have poor vision to begin with. They hunt with their heat pits. There are snakes that are 100% blind that can eat no problem.

I offer food to all my snakes during shed. Out of all the times I have offered during shed, I think I had one refusal.

There is nothing wrong with offering food during a shed, it will not hurt the snake. Some will eat and some won't. The only way to find out is to offer it to them and see.