That is heartbreaking. It does look like he's missing an eye, but I can't tell about the other eye. Aside from keeping it clean and quarantining him, I'm not sure what else could be done. Is he eating and drinking or doing anything normal at this point?
The best would be a good vet. Keep him inside away from flies. They will lay eggs in the wounds. Keep the wounds clean with saline solution. Give the duck some supervised time in a tub of lukewarm water. Clip the feathers around the wounds to half an inch long.
Add vitamins with electrolytes and probiotics to his water twice a week. Make sure he gets good nutrition.
Be prepared to use oral antibiotics. The duck really needs a vet.