Hordeolum Hordeolum externum 2009-10-27T11:33:07Z Hordeola externa are acute purulent infections affecting the sebaceous glands of Zeis or the apocrine sweat glands of Moll, often caused by staphylococcus infections. In contrast to chalazia, hordeola are extremely painfull and can cause extreme local swelling. HP:0010607 UMLS:C0019919 SNOMEDCT_US:1489008