My cat has some type of wart on her eyelash. Would you have an idea of what it is?

My cat has had this thing on her eyelash line for quite awhile. It really looks to be an ingrown hair boil. She has eyelashes growing out of it. My cat used to be a stray. I remember opening the door to get the mail and she came running into the house, whining for food. She was flea infested and starving. Even from that time, she had that wart on her eye. I noticed it within the week I took her in.