oscar cloudy eye

Usually when fish get 'cloudy' eyes, it's because of dirty water. This is usally due to over feeding, or improper living conditions (small tank). Do plenty of water changes. If your oscar has a cloudy eye, there can't be enough water changes. If the tank is too small, find a bigger home. This is really the only cure to it, as it will come back no matter how many water changes you do now (if the tank is too small).

How big is the tank and how big is the oscar?