Board Thread:General Discussion/@comment-24252369-20131208101448/@comment-3298236-20161202042809

He has two separate eyes, they're just so sylized it looks like they're conjoined. Artist Naoto Oshima has gone on record saying that he drew inspiration from old school western cartoon characters when designing sonic, which would explain the cyclops look as many classic cartoon characters have the same eyes as sonic :



Despite the clear gaps between the eyes of these character's, It's still pretty clear that their artists intended for them to have two eyes when creating them.

But if you still don't believe me, just look at Sonic CD. In the stage 'Wacky Workbench' It's possible for sonic to get electrocuted, which lasts for little more than a second. During this time, sonic's skeleton can be seen, albiet only briefly:



If you look look closely at Sonic's skull, you'll notice two completely separate eye sockets. If sonic were actually a cyclops with two pupils, there would only be one socket. And if you think there's a tiny gap connecting the two, look closer, because that's just his nose.