I also have no problems with blind or eye damaged fish.
I had a pair nicararguense that spawned 3 times after a bout with ick, and a 2ndary infection damaged their eyes.
The photo above, is post infection.
A 12" cichlid in a 75 gallon is quite cramped, especially housed with any other fish.
To prevent infections like this I would suggest every other day 30-40% water changes to keep water quality high, a 12" cichlid pumps out plenty of urine, and in a tank that small, for the size fish, a tank full of urine soup happens quickly.