The tarsal glands of Meibom (glandulae tarsales) are large sebaceous glands located in the eyelids and, unlike those of the skin, are unassociated with hairs. According to Duke-Elder and Wyler, 1 they were first mentioned by Galenus in 200 AD and later, in 1666, they were described in more detail by the German physician and anatomist Heinrich Meibom, after whom they are named.

Lipids produced by the meibomian glands are the main component of the superficial lipid layer of the tear film that protects it against evaporation of the aqueous phase and is believed also to stabilize the tear film by lowering surface tension. 2 Hence, meibomian lipids are essential for the maintenance of ocular surface health and integrity. Although they share certain principal characteristics with ordinary sebaceous glands, they have several distinct differences in anatomy, location, secretory regulation, composition of their secretory product, and function. Functional disorders of the meibomian glands, referred to today as meibomian gland dysfunction (MGD), 3 are increasingly recognized as a discrete disease entity. 4–8 In patients with dry eye disease, alterations in the lipid phase that point to MGD are reportedly more frequent than isolated alterations in the aqueous phase. In a study by Heiligenhaus et al., 9 a lipid deficiency occurred in 76.7% of dry eye patients compared with only 11.1% of those with isolated alterations of the aqueous phase. This result is in line with the observations by Shimazaki et al. 10 of a prevalence of MGD in the absolute majority of eyes with ocular discomfort defined as dry eye symptoms. These observations noted that 64.6% of all such eyes and 74.5% of those excluding a deficiency of aqueous tear secretion were found to have obstructive MGD, or a loss of glandular tissue, or both. 10 Horwath-Winter et al. 11 reported MGD in 78% of dry eye patients or, if only non-Sjögren patients are considered, in 87% compared with 13% with isolated aque-