Betta bulging eye

Question
I have a Beta that is close to 9 months old.  I noticed this morning that his right eye looks as if it has popped out of his head.  He is in a filtered 35 gallon tank with three other community fish.  The eye is slightly milky but not bad.  No aggressive behavior goes on and no other fish is exhibiting this problem.  Any suggestions?

Answer
I assume the betta is a male.  He needs his own tank.  Even though you may not see it, the betta may be feeling some kind of stress.  Whether this is true or not, you will probably need to isolate him.  You don't need heating or filteration.  You can get a cheap gallon tank at petsmart or walmart.  

Good luck,
Paul