It could be trauma but most likely popeye. Way to treat it first is use a quarantine tank. I successfully treated a fish recently. I used Jungle Fungus clear which is essentially is Nitro for meds. Also I used General cute which is Metro and prazi. I also did a lot of epsom salt treatments. Epsom helped a lot. It can be deadly and kill the fish. Mine was 5 times worse than that with white fungus on eye and now you could never tell.
I also did Penicillin antiobiotic treatment but I did that when it got better might be overkill.
All of this must be used in hospital tank. Get a 5-10 gallon.