Likely a cyst. I've seen them a lot. Sometimes they need to be removed, sometimes they go away (though not often). I had one dog years ago who had one we would express every month or so. She was very, very, very old with heart and kidney issues so there was no way to put her under to remove it. We would freeze the eye with drops then express (squeeze like a big zit) the cyst. Luckily she was a very patient girl. After about a year it didn't seem to get big enough to bother her anymore so we left it alone. Some breeds seem to be more prone to them....yorkies, schnauzers, chihuahuas and cockers are the breeds I've seen them most.