my character have a poor eye implant ( read bulky one ).. my Dm ask me if i can get a helmet to protect my head. Event if i have a bulky eye implant i think it is possible. i dont see any rule about that.

Does some one saw something in the ruling ??

Depends on the helmet. If its one that is more enclosing than, say, a bike helmet? You'll probably need to have the helmet custom-fitted.