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02/11/2025, 00:10 Otic & Ophthalmic Disorders | Dermatological Disorders

Dry Eye Disease (DED)

Dry eye disease is a common condition that occurs when your tears aren't able to provide adequate lubrication
for your eyes.
Abnormalities in the tear layer cause less-than-optimal lubrication of the ocular surface, with subsequent
inadequate tear production or fast tear fluid evaporation.
Tears are the fluid produced by your eyes to keep them wet and functional. They are made up of water,
electrolytes, lipids, proteins, and mucins, forming the "tear film."

Dry eye disease pathophysiology

"Tear layer" (or tear film) refers to the thin, three-layered film that forms on the surface of your eye.
The tear film consists of:

an inner mucus layer,

a middle watery (aqueous) layer, &

an outer oily (lipid) layer,

each with specific functions in protecting, moisturizing, and lubricating the eye.
Abnormalities within any one of the tear layers can result in ocular discomfort.

Dry eye disease (DED) is characterized by a loss of homeostasis of the tear film accompanied by ocular
symptoms.
Loss of homeostasis of the tear film results in Tear hyperosmolarity, which is a central feature in the
development and progression of dry eye disease (DED).
Causes of Loss of homeostasis of the tear film:

Decrease in tear production
Increase in tear evaporation.

Hyperosmolar tears arise from reduced tear production or increased evaporation, leading to a high
concentration of salts in the tears which damages the eye's surface cells and worsens the overall tear film.

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