My comment relates to UI in the editor (as did OneMoreNameless'sssss), and assumes while the eye sightlines are toggled to ON, they will be updated with each change to the room (since, for example, it doesn't make sense for the eye to keep looking through a wall you've just added)
Not sure I understand Tahnan's post, though.
Eyes can see through monsters anyway so not sure why such a feature would be useful.
Since we're talking about the editor, if you want to see what the eye is looking at when a door opens/crumbly wall is broken then just delete that element (and then undo your last change).
____________________________
New to DROD? You may want to read
this.
My
Holds and Levels:
Click here to view the secret text