Eyelash trichomegaly is defined as eyelashes which are found to be of increased length, thickness, and pigmentation. It can be present at birth as part of variety congenital syndromes or as a benign familial trait. Congenital syndromes that include eyelash trichomegaly as a defining diagnostic feature, are Oliver-McFarlane syndrome [DS:
H01898] and Cornelia de Lange syndrome [DS:
H00631]. It has been identified that mutations in FGF5 underlie the trichomegaly. There are also acquired conditions and drugs that are known to cause eyelash trichomegaly. For example, acquired conditions, such as allergic rhinitis, atopic dermatitis, HIV infection, and certain eye diseases, have commonly been reported to be associated with increased length of the eyelashes.
