I have been feeding jumbo krill and prawns, The arows have not had live food for over a month. If the fat build up did recede then will the eye sockets go back to normal?
Epsom salt might not be a good idea. Its made of magnesium sulfate so all it does is make your fish crap more. Just stick with regular aquarium salt or morton's kosher salt.
How are the other eyes, right side. My one large silver with DE in both eyes can no longer feed from the surface. It'll take you aros a week or so to adjust to the DE. Soon they'll be eating and acting like nothings wrong.