The upper and lower eyelids have many small glands inside them. These are called meibomian glands. They secrete oils that keep tears from evaporating too quickly and keep the surface of your eyes moist.
If your meibomian glands become blocked by thickened oils, your eyes will become dry and may feel irritated.
A blocked oil gland is more likely to get infected. This causes eyelid redness and swelling (blepharitis). Sometimes a stye or bump forms. This condition may take 6 to 12 months to clear up fully. Use the home treatments below to improve your condition.