What is Dry Eye- How does it Occur?

What is Dry Eye?

• Dry eye is a condition in which a person doesn’t have enough quality tears to lubricate and nourish the eye.
• Tears are necessary for maintaining the health of the front surface of the eye and for providing clear vision.
• When our Eye blink it spreads the tear and provide lubrication that helps us to:
  • Reduce risk of infection.
  • Remove the debris.
  • Keep surface smooth and clear.

Dry Eye Mechanism:

• The four inter-related mechanisms thought to be responsible for the manifestations of dry eye:

1. Tear instability,
2. Tear hyperosmolarity,
3. Inflammation and
4. Ocular surface damage.

1. Tear Instability:

• This occurs when the tear film, which protects and lubricates the eye, does not maintain its normal stable layer.
• Instability can lead to uneven distribution or rapid evaporation of tears, causing dry spots on the ocular surface.

2. Tear Hyperosmolarity:

• This refers to an increase in the salt concentration of tears. When tear production decreases or tear evaporation increases, the remaining tear film becomes more concentrated.
• This hyperosmolarity can damage the surface cells of the eye, leading to inflammation.

3. Inflammation:

• The increased osmolarity of the tear film and damage to the ocular surface can trigger an inflammatory response.
• Inflammation further damages the surface of the eye and the lacrimal glands, exacerbating tear instability and hyperosmolarity, creating a vicious cycle.

4. Ocular Surface Damage:

• The culmination of tear instability, hyperosmolarity, and inflammation can lead to damage of the cornea and conjunctiva.
• This damage can manifest as dry spots, micro-abrasions, and in severe cases, can lead to the breakdown of the ocular surface, affecting vision and comfort.

Inflammation in the conjunctiva, accessory glands and ocular surface is present in 80% of patients with any kind of Dry Eye.

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