I enjoy the Castlevania show interpretation of vampires being evolved predators and a large geometric shape being shoved into their vision causes them to freak out. Kinda like a cat seeing a cucumber.
I'd be ok with it if they were like zombies or something, but they're intelligent so that explanation just feels like such a stretch to me. Are vampires also affected by window muntins and fences? Can I fend off a vampire attack with a suit of graph paper armour? Do they freak out at the sight of jungle gyms?
I mean, if you shoved a jungle gym in my face I would probably have an issue with it.
As a practical similarity, ever heard of speech-jamming? The idea is that you can play someone's own voice back to them with a slight delay and it will cause them try and listen and speak at the same time resulting in slower speaking or even the inability to speak normally.
I feel like a vampire could have unique instincts or mental processes that could be messed with in a similar way. Maybe it's like how people can see faces in very simple shapes; they see threats instead.
I version I read in a book (can't remember that name of it) was whatever religus artifacts the vampire had faith in whould be the what hurt them, (Star of David hurting a Jewish vampire)