Sounds like expothalmia which is swelling of the eyes due to a number of reasons...commonly this can be caused in fish that have been exposed to too much gases in their water...nitrogen is a common gas that causes this. Basically is causes bubbles to form within the blood and body due to the high gas pressure in the tank or bowl, thus causing the eyes to protrude. Simply cleaning the water can help relieve the fish from this disorder...clean you water a little more frequently to get rid of all of the gases...they disorder should slowly go away. Try this method first!
Another cause of this disorder can be bacterial, which is less common then environmental causes but happens when the water conditions are permissible for bacterial growth. With that said, again clean your whole tank and gravel, change the water. Salt baths can help clear up some bacterial infections, use a spare tank to create a salt bath from aquarium salts. Most aquarium salts (buy only aquarium salts for this) will give you the correct dose per gallon of water. Leave them in the bath for a bout 5 minutes and place back into the tank. Make sure your salt dip is the same temperature as your tank water to prevent thermal shock. I would not do salt baths often, once a day for a few days should do. If salt baths do not do the trick there are petstore medications that can be bought to specifically treat expothalmia ("pop eye" is the aquarium name). These should be tried last as they can suck the oxygen out of your tank and are a little more dangerous if you give the wrong dose.
Pop eye can also be a symptom caused from other disorders such as the beginning onset of dropsy...if the body starts to swell up a lot and the scales seem to protrude off of the body this could mean your fish has dropsy...unfortunately dropsy is untreatable in its late stages, but your fish can survive. I have had a dropsy fish alive for 4 months so far since she has been sick. You will know if your fish has dropsy...they look like balloons and their scales pop up and they look like little pine cones.