In F. Scott Fitzgerald's The Great Gatsby, the author introduces...
...a stout, middle-aged man, with enormous owl-eyed spectacles...
He is in the library, rather drunk, studying the books Gatsby has collected. The man is amazed that Gatsby has real books: he was expecting cardboard, false-fronts to make it look like the library had books. It is interesting that the "owl-eyed" gentleman expects to see fake books. He is surprised when he confronts the real thing. His expectation of illusion is an interesting point.
The man continues by saying:
It's a bona-fide piece of printed matter. It fooled me. This fella's a regular Belasco. It's a triumph. What thoroughness! What realism!
This man seems to know something of books. He expects to find a library empty of books. This may indicate that he is familiar with the kinds of people who create lives based on illusion, but seems to feel that Gatsby is not one of these because he has taken the time to furnish his library with real books. This does not seem particularly important at that time.
The fact that he is described as "owl-eyes" could indicate two things. Owls are symbolic of wisdom. Second, an owl has precise eyesight. With this said, we might imagine that the man is perceptive. We might think he knows the real deal when he sees it—that he can spot a fake.
It might appear ironic, then, that this man is the only person who shows up at Gatsby's funeral—he obviously admired Gatsby, but it is surprising, too, that he didn't anticipate that Gatsby's funeral would be so poorly attended. While the man in the library seems to be able to recognize the difference between appearances vs. reality (a major theme in the story), he does not expect such phony, parasitic people among those who spend appear to be so close to Gatsby. However, it says that the man has "enormous owl-eyed spectacles."
"Owl-Eyes" sounds like someone with the ability to see the reality in a situation. But the glasses he wears may actually indicate that his "sight" is not that strong. He may actually be symbolic of Gatsby who...
...fail[s] because of his inability to separate the ideal from the real.
Owl-Eyes may serve to foreshadow Gatsby's inability to understand the real world. Hanging on to Daisy places her in his car the night she kills Myrtle with Jay's car. His insistence to protect her sets him up as the target of Wilson's misguided desire for revenge. Daisy's failure to attend Gatsby's funeral, even in light of his sacrifice for her sake, indicates that Gatsby was swept up by his illusion of Daisy—he never could see that she really cared less for others than herself. What he thought they had, was not based upon reality.
Owl-Eyes sees the books in Chapter Three and is impressed. However, while the books are there, is there any indication that Gatsby ever reads them? The man takes the presence of the books as proof of Gatsby's authentic sophistication. Owl-Eyes, like Gatsby, may believe what he sees and take it at face value. However, the reality of Gatsby's faithless friends is as surprising to Owl-Eyes as Daisy's ability to also love Tom Buchanan is to Gatsby.
Even the most perceptive of people can sometimes be misled by what they believe they see.