It looks like excess mucous that is on the eye. The fish probably damaged the eye and the excess mucous is protecting the wound.
Make sure the water is good and do a 75% water change and gravel clean the substrate each day for a week. Make sure any new water is free of chlorine/ chloramine before it is added to the tank.
Clean the filter if it hasn't been done in the last 2 weeks..
If the conditions are good the fish should heal up within a few days without any medication. If it gets worse after a few water changes, then it might need treating. But at this stage it just looks like excess mucous.