Thanks everyone - it's good to know that it might just be age-related. I don't recall DD10 having these issues at age 7, but she ramped up her reading very quickly and now reads faster than I do.
DS does read on his own - mostly comics (Pokemon, Sonic, Big Nate). But his preference seems to be to ask me to read to him.
The other thing that slows him down when reading aloud is perfectionism - he wants to get the expression just right and often re-reads a sentence until he likes how it sounds. Do other kids do this?
I think I will go ahead with the vision assessment, just in case.
