The word you are looking for is cyst. Here's a picture of a woman with a cyst in her eye. The other pictures I found were kind of nasty.
A cyst is basically a swelling of fluid that becomes like a bag. Here is the definition for cyst if you want to know more.
A cyst is basically a swelling of fluid that becomes like a bag. Here is the definition for cyst if you want to know more.
