What is Evaporative Dry Eye Disease (EDED)?

• A. Tear film instability due to lipid layer dysfunction without decreased aqueous production
• B. Decreased tear production due to lacrimal gland dysfunction
• C. Inflammation of the cornea without tear dysfunction
• D. Primary infectious keratitis causing tear film thinning

Answer: (A)

Evaporative Dry Eye Disease is driven by tear film instability caused by a dysfunctional lipid layer. The lipid layer, produced by the meibomian glands, sits on top of the aqueous component and slows evaporation. When this lipid layer is impaired, the tear film evaporates too quickly, breaking up rapidly and leaving the ocular surface dry, even though tear production by the lacrimal glands remains normal. Clinically, this often shows a normal or near-normal Schirmer test (normal aqueous production) but a shortened tear film breakup time and signs of meibomian gland dysfunction or lid margin disease.

Decreased tear production due to lacrimal gland dysfunction would be aqueous-deficient dry eye, which presents with reduced tear production rather than rapid evaporation. Inflammation of the cornea without tear dysfunction does not address tear film instability. Primary infectious keratitis involves infection and can thin or irregularize the corneal surface, not specifically the lipid-driven evaporation problem seen in evaporative dry eye.