I'm sure @neilhimself.neilgaiman.com would point out in his deeply polite fashion that inasmuch as the Corinthian is a magical dream creature, gross (in both senses of the word) anatomy issues are not a real concern, therefore the problem here is indeed my brain, not his, his is pure and unsullied

Considering HOW eyes themselves work, that they're kinda self contained entities in our skulls; I've always assumed his vitreous fluid is just that corrosive anything consumed become nutrient soup that can pass barriers safely.

I’m one of the people that gets haunted by this imagery, like deeply disturbed by it - but I didn’t think they digested stuff at all, they just hold things (like how a dog does). Maybe they bark, too? Or do they talk?

If you imagine him explaining the eyesophagus in his narrator voice though it's quite upsetting.