A stye is caused by a bacterial infection, such as Staphylococcus aureus, on the edge or inside of the eyelid, and is also medically known as a "hordeolum."
A part of the eyelid becomes swollen and red, initially itchy, and gradually the pain intensifies. If it worsens, the swelling of the eyelid will increase, and pus will appear.
If left untreated, the bacteria can multiply repeatedly, potentially leading to painful purulent inflammation. This is one eye condition that requires particular attention during swimming pool and beach seasons.
A stye is known by various names in different regions, in addition to "monomorai" (stye).
Please also check out the content that summarizes the distribution.