Why Do We Blink? Why Do We Produce Tears?

Posted by Bruce Dornn on

The cornea is the only part of the anatomy that has no blood supply—thank goodness, it would be difficult to see through red! The body has invented a way of feeding oxygen to the cornea because of this lack of blood supply. Small glands in the lids called Meibomian glands produce a complex mixture of oils that build up in a layer(or puddle) on the bottom lid margin. Approximately 22 times a minute, the upper lid comes down to meet the lower lid (blinking). The upper lid then spreads a smooth layer of oily tear over the front surface of the eye. This oily tear has some very critical functions:

1. Absorbs oxygen from the air around us and becomes hyper-oxygenated. This heavy concentration of oxygen then soaks and feeds the surface of the eye.
2. The tear film provides a protective coating on the surface of the eye to prevent pollen, dust, mould, pet dander, and other airborne pollutants from sticking to the surface of the eye. This prevents chronic allergic reactions.
3. Tear film contains an incredible amount of immune cells and antibodies. It helps the exposed ocular surface “fight off” infection from millions of airborne bacteria and viruses.

Any disruption of this normal production of tears and blinking mechanism will significantly impact eye health and vision. Unfortunately Dry Eye Disease (DED) is very common and often times, it’s under diagnosed.

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