Fish injuries (eyes)?

Ill start this off by saying that I am in no way a beginner to fish and although this tank is overstocked, i can easily handle it. Right now i have a 55 gallon tank which i just switched over from sand to gravel. There are 9 angels and 3 pictus catfish in the tank. The angels are all female siblings over a year old and show no aggression to each other at all. And i have 6 other small fish in there as well. These 6 are constantly hiding. I do 2 50% or greater water changes on the tank every week. There are also 3 large filters for a combined 250 gallons of filtration or over 1000gph.

I had to switch the tank over from sand to gravel since the pictus cats were killing my filter by constantly swirling the sand into the water. I also added three large ornaments and some plants for them to hide in.

During this change i did a huge water change. The parameters of the water before the water change was 0/0/5. The next day one of my older angels had a white spot on her eye. Then a couple days later, the larger cat had a white spot in her eye as well. Now i know it cant be cloud eye because the water is pristine and no one has flukes or parasites. There isnt any aggression either.

So would i be correct to assume that the white is caused by an injury? Perhaps by the new ornaments? Besides these two fish, none of the others have any injuries. Ive decided to try and treat them with salt instead of meds. But both the angels and cat are sensitive to salt. Would the salt still be beneficial at half a dose? 1 teaspoon per 10 gallons instead of 5? Or would this still be harmful?

Thanks for any help or advise :)