Does crying really helps fight bacteria in the eyes ?

We should know about tear film biochemistry and its composition to know how it protects from bacterial and viral infections .

Tear film consists of 3 layers ,includes

• Outer most lipid layer, derived from Meibomian glands, glands of Ziess and glands of Moll

• The middle layer and the main bulk of tear film which is secreted by lacrimal glands and accessory glands of Krause and Wolfring

• Deepest layer which is secreted by conjunctival goblet cells, crypts of Henle, gland of Manz .
  

What is the composition and how tears protect from bacterial and viral infections?

chemical composition

1. Water

   1. Major component, 98.2%

   2. With salts dissolved Na+, K+, Cl-, HCO3-, Ca2+

2. Proteins

   1. Un-stimulated tears protein concentration: 2gm/100ml

   2. Stimulated tears protein concentration (Crying) : 0.3-0.7 gm/100ml

   3. Protein composition is also important for a healthy ocular surface

   4. Tears contain a large number of proteins, which are secreted by the orbital glands

   5. Tears do not normally contain serum proteins, although these can enter the tears from leaky conjunctival blood vessels under pathological conditions

   6. One of the most important functions of tear proteins is preventing bacterial and viral infections. The major tear proteins like lysozyme, secretory immunoglobulin (IgA), lactoferrin, lipocalin, and peroxidase are antibacterial and antiviral

3. others like aminoacids ,lipids ,metabolites like glucose, pyruvate, etc which are useful for metabolism.

Functions of tear film :

• Form a smooth optical surface by filling irregularities of corneal epithelium

• Keeps the cornea and conjunctiva moist

• Serves as a lubricant for lids

• Transfer air to the cornea

• Prevent infections

• Washes away debris and irritants

• Provides pathway to WBC in case of injury

So even you cry or not tear film protects you from infections .