How do you serve a justice to a fifteen year old boy who lost an eye? Eye for an eye?

Hmmm 🤔 it depends on who he is and where this happened. Because it could range from getting a slap on the wrist to being treated like he robbed a bank. I will give you an example:

When Mark Wahlberg, the actor at the age of 16 went on racist attack of some Vietnamese Americans people, calling them gooks.
He hit one man, Thanh Lam, over the head with a five-foot wooden stick, breaking the stick and knocking the victim unconscious.
He later punched a second man, Hoa Trinh, in the face.
He was charged with attempted murder, but only did 45 days.

But on the other hand Kalief Browder, a black teen was charged at the age of 16 with stealing a backpack and was sent to Riker's Prison with grown men where he was raped. He was jailed for nearly 3 years.
So it depends what mood lady justice is in on that day and whether that child is seen as human or just someone who needs guidance.

Corporal punishment is a problem when guilty verdicts can be found later to be false.

How will you give the boy back his eye and sooth the trauma when evidence comes to light a year from now he wasn’t guilty of the crime?

Eye for an eye.

Wait did your boy do this?

He should be put into custody and tried as an adult with assault with intent to do serious harm.

You take away all their social media access

omg

Arrested and charged as an adult for attempted murder, first sentenced to juvenile, then tramsfered to adult prison on their 18th birthday.