Naso tang with a cloudy eye

[pirate]

As the title say, I have a naso with 1 cloudy eye. It looks like a film over his eye, but only part of it. None of the other fish have it, except my domino damsel is turning white. Everbody else looks fine. They are all eating like pigs. I had a bit of ich that went thru the tank ( yellow tang and the regal)about 2 weeks ago and no one else showed any sign of it.

WhenI checked the water parameters yesterday it was all fine.
ammonia between 0 and 0.5
nitrite did not regester
nitrate did not regester
Temp fluctates between 79 (night) and 80 (day)


I dont have any thing else for testing.

Livestock in the tank

2 false clowns
3 green chromis
1 regal tang 4" or so
1 yellow tang 4" or so
1 naso tang 4" od so
1 bengaii cardnal
2 damsels
1 domonio damsel 3" or so
and a yellow watching gobi pistol shrimp pair
And a very light clean up crew
and some corals

Tank is a 150g with a 40g sump.

Thanks for the help.