Dry Eyes

Dry Eyes

Clinically reviewed Aug 29, 2026 Updated Aug 30, 2026
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Clinical Snapshot

Dry eye disease (DED) is defined by the TFOS DEWS II consensus as a multifactorial disease of the tears and ocular surface, resulting in symptoms of discomfort, visual disturbance, and tear film instability, with potential damage to the ocular surface. It is accompanied by increased tear film osmolarity and inflammation of the ocular surface, and — for the first time in this 2017 update — neurosensory abnormalities are included in the definition, reflecting how directly the corneal nerves are involved in symptom generation.[1]

Contemporary classification places every case somewhere on a continuum between two mechanisms rather than in one fixed bin. Aqueous-deficient dry eye reflects insufficient tear volume from lacrimal gland dysfunction (Sjögren-associated or non-Sjögren). Evaporative dry eye reflects excessive tear evaporation despite roughly normal tear production — most often from meibomian gland dysfunction (MGD), where a deficient or abnormal lipid layer allows the aqueous layer beneath it to evaporate too quickly, though inadequate lid closure, reduced blink rate, and ocular surface disease also contribute. Elements of both mechanisms coexist in most real patients, and evaporative disease — driven by MGD — is now recognized as the more common of the two, whether it occurs alone or alongside a degree of aqueous deficiency.[1][2]

Diagram of the three tear film layers: an outer lipid layer, a middle aqueous layer, and an inner mucin layer over the corneal epithelium
The tear film's three layers, outermost to innermost: lipid (meibomian gland secretions), aqueous (lacrimal gland), and mucin (conjunctival goblet cells) over the corneal epithelium. Deficiency or dysfunction of any layer — most often the lipid layer in meibomian gland dysfunction — produces dry eye disease. (Vinne2, CC BY-SA, Wikimedia Commons)

DED is genuinely common: global prevalence estimates range from about 5% to 50% depending on the population studied and the diagnostic criteria applied, prevalence rises with age beyond the fifth decade of life, and women are more often affected than men.[3] A history of lid, ocular, or refractive surgery; age over 40; female sex; certain medications and systemic diseases; smoking; computer vision syndrome; and frequent exposure to harsh environments are the risk factors most consistently associated with DED — see Etiology and Risk Factors.[4]

Professional reference only. Apply clinical judgment and verify patient-specific decisions against current authoritative guidance and product information.

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