Cloudy eyes is usually due to a pH in-balance, i.e. low Alkalinity. Alkalinity is ur buffering capacity for ur pH, without/low alkalinity nothing controls ur pH from swinging. causes a lot of stress for fish!
i would test the water and see what the KH and pH is and monitor it. i would also look at the filter and see if it needs service since build up of organic matter in the filter can also cause pH swings.