I think the risks of messing with his eyes far outweigh the potential benefits of getting an eye cap off. Eye caps aren't really all that dangerous unless they build up for a very long time, and it's possible to permanently maim the animal by poking around at its eyes. If it makes you feel better, I see no harm in putting drops of mineral oil or visene on his eyes. DON'T tweeze them or rub them, though.
What I'm wondering is this - you said only the outermost eye cap came off with his last shed. When you looked at the face part of that shed, was the skin of his eyes there or not? Were there two empty holes where the spectacles should have been? If there WAS something there, he does not have retained eyecaps. He might have some other issue that makes them look weird, but it isn't retained eyecaps. Look at the shed to figure out if that's really the problem, not at his eyes.