I agree about the HITH, and that the eye infection is probably bacterial, and basically related to the cause of the HITH.
What is your water change routine, frequency and how much do you change in @ gallons with each water change?
Related to that, what is the normal tanks nitrate concentration before a water change?
What kind of filtration, and how often are the filters cleaned
What is the tank size in gallons?
HITH and related bacterial infections are usually due to a lack of sufficient water changes, and filter cleanings.