Tests confirmed that Firmino had suffered no lasting damage and he was back in action for Liverpool just three days later.
However, the 27-year-old feared losing sight as a result of the collision with Vertonghen, telling Sky Sports News: "I was scared of going blind in one eye and not being able to see again.
"Thank God nothing like that happened and it gradually improved day after day. Of course, I've been taking my medication and looking after it. Your eyes are very important as a professional footballer. Thank God everything is OK now."
Firmino has scored three goals in 10 appearances for Liverpool this season, including the second goal in the 2-1 win against Spurs on September 15.