Can you tell us whether it is in both his eyes/ recent onset/ the cause for deterioration (trauma/ congenital)?
Depending upon these questions we can suggest you better as it guides us to come for a conclusion.
If it is because of a Fresh Retinal detachment
, then it can be fixed by surgery.
But if it is persisting since childhood and noticed now, I am sorry that the retinal layer has already been degenerated that nothing could be done except maintaining the structure of the globe and maximizing his persisting good vision with aids
There is nothing wrong in taking a second opinion
with a Retina specialist in your area to reconfirm the diagnosis .
I am unable to comment further without a detailed picture of the retina .
So take care and post us when you get more details to guide you more.:)