Sorry about your fish.
The cloudy eye was probably secondary to some sort of parasite. I would not be afraid to dip a fish in the future if you are careful.
I am a fresh water dip believer. I match the temperature, ph (I use a product called ph up) and aerate the water. I have never lost a fish (knock on wood). Most fish I leave for 4 -6 minutes. If they seem week or become listless / just lay down I shorten it. I have dipped a lemon peel, several tangs, a hawk fish, a large angel and a wrasse among others. Most of the fish I have dipped are when I first get them to kill parasites.
If you do it in a clear plastic container you can see all the stuff it explodes off an infected fish. After I dipped the hawk fish it looked like a snow globe there were so many dead flukes.
B.