Most eye problems in fish are caused by poor water quality or scratches. They heal up quickly without any medication if the fish is kept in good conditions.
Test your water for ammonia, nitrite, nitrate and pH.
Make sure there is 0 ammonia, 0 nitrite and less than 20ppm of nitrate.
Make sure the pH is above 7.0.
Do a 75% water change and gravel clean the substrate every day for 2 weeks.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.