A sty can be caused by:

  • Poor hygiene. A sty is usually caused by bacteria, especially the bacterium staphylococcus. Touching your eyes with unwashed hands can transfer bacteria to your eyelids.
  • Eyelid inflammation. Chronic inflammation along the edge of the eyelid caused by a condition called blepharitis can cause a sty to form. Blepharitis may be associated with underlying conditions, such as seborrheic dermatitis or rosacea, a skin condition characterized by facial redness. Following your doctor's instructions for treating your blepharitis can help prevent sties.
Jun. 13, 2012