This is part of a series with a girl messing with yukkuri's eyes. I think the name of the series is 把眼睛換成玻璃珠. It was posted here: http://www.freeyy.org/himitu/pixmicat.php?res=24288 A translation of this series would be much appreciated.
Looks like its just another yukkuri biology story. The eye play and cross-section cuts are just a demonstration of how few "organs" yukkuris have.
The last picture shows that yukkuris don't really need eyes to see. Patchouli can "see" how her eyes have been replaced with glass beads(?) in the mirror so she vomits herself to death. Youmu can see herself in the mirror as well but shes so stupid she doesn't realize the change so anon just kills her.