A stye is caused by a bacterial infection, most commonly by Staphylococcus aureus bacteria, which infects the oil glands or hair follicles in the eyelid. This infection leads to a blocked gland, resulting in a red, painful lump on the edge of the eyelid that resembles a pimple
. The bacteria normally live harmlessly on the skin but can cause infection when trapped in a gland or follicle, often due to factors such as touching or rubbing the eyes with unclean hands, blocked glands from oil, sweat, or makeup buildup, or underlying conditions like blepharitis, diabetes, or skin conditions like rosacea
. There are two types of styes:
- External styes, which form on the outer eyelid edge, usually in an eyelash follicle or oil gland.
- Internal styes, which develop inside the eyelid in the meibomian glands and tend to be more painful
In summary, a stye is caused by a bacterial infection of an oil gland or eyelash follicle in the eyelid, primarily due to Staphylococcus aureus, often triggered by blocked glands and poor hygiene
