Towards the conclusion of the episode, we see
The long awaited Cleganebowl between Sandor and Gregor.
During this fight
Gregor gouges Sandor's eyes, similar to how he did with Oberyn Martell.
We see them visibly wounded, with blood pouring out, however they still appear to be able to finish the fight. Where would this blood have come from, whilst not robbing
of his vision?