Actually not just superheroes; if I recall correctly, the entire cast of “Annie,” including the little dog, had not so much as a single pupil or iris to share between them. It’s not all supers, either: the infamous Batman frame shows Batman and the Green Lantern without, Flash with, and that guy in the background… well, he’s too far away to tell.
I’m curious what, if any, rationale there is for this particular comic-book trope. I’ve always found it a little odd, even disturbing, to look at all those blank stares, so I’m sure there must be SOME good reason, right?
When they wear a dark mask, adding in the iris of the eye makes the eyehole of the mask lose its distinctive shape, and depending on where it’s placed, it can sometimes look quite unusual; you can lose definitive character detail, or cannot show the facial expression you’re trying to portray properly. It’s sometimes easier to just eliminate some of the elements and simplify. Then, once established, it becomes a character tradition.
Then you can retro-fit an explanation, such as the masks have a protective layer over them like goggles.
There was one Batman story from the 1950s where they drew in his eyes (irises as well as pupils). The reason was that someone was trying to deduce Batman’s identity from available clues, including the color of his eyes, so they felt compelled to put it in (Batman figured out what they were up to and faked them out with colored contacts and the like).
But Batman with visible eyes looked — creepy.
Just showing white spaces in Batman’s cowl and Robin’s domino mask might be a stylistic choice and all, but it looks better than the alternative, unless you’re doing realistic art.
After all the problems that the Child Protective Services investigators gave Batman about Robin, they’ve all been very cautious about taking underage sidekicks as pupils to mentor.
