Over on our Youtube channel, Skyvisioncenters105, Dr. White is in the middle of a series on Dry Eye. We've talked a bit about Dry Eye here as well, but it's so very common it's worth talking about some more!
Our tears are a complex mixture, an EMULSION, of 3 distinct, separate substances. The major component or part of our tears is salt water; we call that the AQUEOUS component of the tears. The aqueous component is made by microscopic glands on the white part of the eye. Other glands right on the eye make the MUCIN component. The third part of our tears is an oil, or LIPID component, and it is made by glands that are just inside your eyelashes on your eyelids.
Your tears are a mixture of all three parts. They are kind of like Italian salad dressing after you shake it up! There is more Mucin closer to the surface of the eye, kind of like the spices that start in the bottom of the bottle of dressing. Aqueous is found throughout the tear layer, just like the vinegar in the Italian dressing. And the Lipid part is mostly on the very outside of the tears, but just like the olive oil in the salad dressing after you shake it, the Lipid is also throughout the tears.