Browsing the tag group "eyes" I noted there was a tag for really small pupils... but non for the iris itself. Thing is, the iris the the tiny little dot and does not need to have small iris for it to meet the criteria of the tag. But what about images that also have a tiny iris? Or in the occasional case a small iris but a comparatively large pupil or no pupil at all?
Examples of the small iris:
So I suggest a new tag. A constricted_iris or small_iris.