Disruption of tear-film homeostasis (altered composition, reduced production, rapid evaporation) and resulting ocular surface inflammation cause the discomfort and blurred vision of dry eye disease. Many cases are caused by tear evaporation due to meibomian gland dysfunction. Other precipitating factors can include lacrimal gland dysfunction, poor eyelid function, environmental factors, extended screen time, inflammatory conditions such as Sjögren's syndrome, and use of some ocular or systemic drugs such as antihistamines, retinoids, or selective serotonin reuptake inhibitors (SSRIs). Benzalkonium chloride, a preservative used in some eye drops, can cause eye irritation and exacerbate symptoms of dry eye disease; use of preservative-free ophthalmic preparations is preferred. Dry eye disease is most prevalent in females and older adults, but its incidence in young people is increasing, possibly because of increased screen time.