Cloudy eye

I've already posted a thread about this about two weeks ago but I wanted to start a new one. Anyways I purchased my Achilles tang two weeks ago and has been fighting this cloudy eye since my water parameters are NITRATE-10 ppm, nitrite-0 ph-8.1, ammonia 0. I also use ro/di water. I'm just fustrated bc it's been like this for two weeks. I want to do something for him but idk how? Please I would like to hear some advise. Thank you