Don't give up hope. I was legally blind for many years until I had my sight restored via surgery.
Could you tell us his first name? It helps me to pray for somebody by name. Thanks.
They can work miracles with lasers these days. My left eye was pretty much destroyed by a piece of flying wood off a table saw(Wear safety glasses). It took four months and three laser sessions, but they got the vision back to 20/20.
Prayers for your son. If they can stop the swelling before too much damage occurs, he has a great shot at getting his sight back.