(I have some concerns about this.  I am not trying to play rules lawyer, and I am not metagaming to gain an unfair advantage here.  But to my understanding unless a creature type and entry state it has Blindsense/Blindsight or something that similarly allows it to negate sight based effects, all monster entries are assumed to have to rely on sight, even if they don't descriptively have eyeballs or eyes.  By stating that the constructs just ignore the effects of the spell, it kind of sounds like you're just making stuff up on the fly.  I'd really like to know if you are making this ruling because you<em> 'think it's logical'</em>or because you didn't realize that monsters have to rely on sight unless stated otherwise?  Cause I have serious issues with rulings that comes suddenly out of left field that violates the way the normal flow of the game works.  I'm stating this because I've already been cool with getting ambushed without an initiative check, and I'm not doing anything to the monsters, I am just trying to avoid taking that hit- so I hardly consider what I am asking to be unfair.  I'd like to ask you to please check your material and reconsider what you just said)