Buttons are able to act as human eyes, on all the creatures created by the Beldam in the Other World in Coraline. When Coraline receives her doll in both the movie and book, she makes a mental comment to herself about how strange and peculiar it is that the doll has buttons for eyes. Later in the film it is revealed by the sweet ghost girl that the Beldam uses the doll's button eyes to spy on Coraline, as well as she did for all three ghost children.
The doll is obviously not the only creation by the Other Mother with buttons for eyes, as the Other Father, the Other Wybie, the Other Mr. Bobinsky, and the Other Ms. Spink and Ms. Forcible have them as well. There is evidence that both of these creations are made of sand/dust, just like all of the other things in the Other World, suggesting that these creatures are actually not real. However, the buttons on them do act as human eyes, allowing them to see within the visible light spectrum. It is a mystery how the buttons actually allow these life forms to see, but one inference is that the Other Mother is actually able to see through them, like she does through the doll, and is able to control their actions to some extent, but it is shown in the film that both the Other Father and Other Wybie have some free will. It is also most very likely that there were other creations with buttons for eyes that were made by the Beldam when she was trying to trap each of the Ghost Children. For instance, there was probably an Other Sister made by the Beldam to portray Wybie Lovat's Grandmother/ The Sweet Ghost Girl's sister.
The Beldam herself also has buttons for eyes, although it is a lot more unclear how her buttons got there. Since the Other Mother hand-makes everything in her world, including the fake people, it's assumed that she hand-sewed the buttons on them herself.
- Other Mother- "Black is traditional. But if you'd prefer pink, or vermilion? Though you might make me jealous!
- Mel Jones- "Buttons for eyes, huh? Coraline, you only dreamed you ate all that chicken. Take your multivitamin at least."
- Coraline Jones- "You're not my mother. My mother doesn't have b-b-b-..." Other Mother- "B-b-b-buttons?! Do you like them?"
- Buttons are mentioned in the Other Father's welcoming song for Coraline, which is meant to be both a nice welcoming gesture, and a warning call.