One of my cherry barbs has a white/gray spot on both eyes. The eyes aren't really clouded but the pupil on both eyes have the spot on it. I noticed this a few weeks ago and then I saw 2 other barbs developing the same thing on their eyes.

I used Jungle Labs 'Fungus Clear' last week and started a second dose yesterday but I don't see any difference.

I had these fish for a year now and change 25% of the water weekly.
My ammonia and nitrite is at 0, nitrate about 10ppm.

Does anyone have an idea what the problem is with their eyes and what I can do?

Thanks for any ideas.