Can you blind someone in self defense?

If you mean permanently blind an attacker, you should only resort to doing it if you are reasonably certain that you are in danger of grave bodily harm or death, have no avenue of retreat and escape, and if you can convince a judge and jury that you sincerely believed you were in danger of grave bodily harm or death. I do not recommend blinding an opponent unless you have absolutely no other way of stopping the attack. There are other less drastic tactics you can use unless you simply know nothing at all about fighting.