It depends on the type of salt,aquarium salt is safe for most aquarium fish if I am not mistaken.I could be wrong. Just thought I'd heard that at some point and was worth mentioning.
I would keep doing water changes everyday maybe 20-30 percent and add some salt to the tank. If you lose the eye not a big deal it won't die. I had an arow like that who had an abrasion from jumping and hitting the tank. It took 6 months to fully heal properly. Was cloudy in the beginning but became normal. Not sure if he was blind in that eye but didn't seem like it. I can physically see the eye moving my wayIt depends on the type of salt,aquarium salt is safe for most aquarium fish if I am not mistaken.