A stye (hordeolum) is a small, painful bump that forms on the eyelid when an oil gland near the base of the eyelashes becomes blocked. It often looks like a pimple and can cause swelling, redness, and tenderness in the eyelid. Many styes will heal on their own within a week, but may often recur. Special heat packs and oral antibiotics may be useful. In other cases, low-level light therapy can speed the recovery. Treating the underlying cause can often decrease or eliminate future styes.