Its difficult to say exactly what is the cause & what treatment is required as there can be numerous causes for cloudy eyes. One common cause is water quality. With better water quality the eyes could clear on its own. It could also be a disease, possibly bacterial, in which case medication may be required. I'd got the route of bettering the water quality & seeing what happens. If it doesn't respond then go the route of medications.
Is there other fish in the tank with it & do any of them show any signs?
Can you provide additional details on your tank.
What size is the tank, how many & what type of fish, what type of filtration you run, how often you change water, how long has the eyes been cloudy? As much info as you can provide can help to get a better diagnosis & solution.