A stye is a common condition affecting the inside or outside of your eyelid. It is a small, painful lump that can cause discomfort. In rare cases, it can cause obstructed vision. Sometimes it can fill with yellow pus.
The condition often resolves itself in a couple of weeks. Further treatment may be required if there are complications. These are rare though. Styes rarely cause lasting eye damage.
A stye occurs when the glands at the base of your eyelashes become infected. They swell up, resulting in the stye.