Understand Milia, the cause & how to treat it What is Milia? Milia are tiny, white bump-like cysts underneath the skin usually found around the eye, on the eyelids and on the cheeks. They can appear in adults as well as in babies. What is the cause of Milia? Milia are formed when skin flakes or keratin become trapped under the skin. Some people are prone to them and they pop up every now and again. If your family also suffer you’re probably genetically predisposed to them.