Take a look at the sentence again:
Because his glasses were so thick, Quincy refused to get
contacts, he worried that equally thick
contact lenses would make him look like a bug-eyed space alien.
The problem occurs between contacts and he. Because his glasses were so thick, Quincy refused to get contacts is a complete sentence. He worried ... starts the next complete sentence. Because these two parts have just a comma between them, they create a comma splice, a major sentence error.
To fix the problem, you could put a period after contacts and then capitalize the H for he.