Current epidemiologic studies indicate that Meibomian gland dysfunction is the most common cause of dry eye disease. Ductal and orifice hyperkeratinisation, which increases with age, is a major cause of Meibomian gland dysfunction. Thus, old age would undoubtedly constitute a predisposing factor in obstructive Meibomian gland dysfunction. However, Meibomian gland structure and function can also be affected by hormonal status, some medical treatments and skin conditions. Tobacco smokers are at particularly high risk of Meibomian gland atrophy. Furthermore, contact lens wear is associated with significant qualitative changes to the meibum.