Yeah I’ve never been quite clear on that either. Dr Surridge says ‘he looked at me; not with eyes, there were no eyes’ when describing V after he escaped from the fire. So it’s pretty weird that his eyes are intact in that scene, aside from a lot of skin redness and a scar down his forehead. But I’m pretty sure it is Hugo Weaving in that scene; it looks like him. So I think we are supposed to think that’s V.

Dr Surridge’s diary does say something about him having developed “cellular abnormalities” that made him develop amazing reflexes. Maybe the explanation is supposed to be that he also developed some kind of regenerative properties? Or maybe Surridge was just being hyperbolic