Coward punch left teen so badly hurt he can't sit HSC exams

A sickening coward punch at a fast food restaurant left a teenager so badly injured that he can't sit his HSC exams.

Tom Blann was blindsided and knocked out cold at a Bondi Beach fast food restaurant just before midnight on October 7.

The 18-year-old suffered a broken eye socket, a broken nose and severe concussion and said he was "terrified" because he had never been struck like that before.

"Everything was pretty blurry," Tom told 7 News.

"I could just hear yelling and screaming, and then before I knew it, there was a whole crowd of people around me."

The attack on Tom was not caught on camera, but nearby CCTV did capture a retaliation punch after the incident.

A CCTV camera caught a man in a white, collared shirt retreating moments before a violent punch was thrown.

"I felt really sick in the stomach, there was just a whole cluster of stuff going on," Tom said.

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Trauma has left the teen unable to sit his HSC exams and he has now been given an average of earlier grades.

"All my friends and like everyone I know, these last four weeks have had their head down doing exams and I've just been at home recuperating," Tom said.

His mother, Meegan Blann, said all of her son's preparation for study has been taken away from him.

"Obviously it's affected him emotionally," Ms Blann said.

"I'm terrified to let him out now of the house and he's also a little hesitant himself.