A human body is 0.4% salt by mass. It is not equally distributed because it is dissolved in water where it is 0.9% by mass, like in the blood. Tears are water from inside your body that is excreted and it will have the same salt content as the water in the body.
So others have the same salt content as the body. If you do not have the same salt concentration you get osmosis with the tissues in contact and water would be pulled into the cells of the eyes until the same salt level is reached.
It is quite complicated for the body to change salt level, the kindies in specialized in that to manage the concentration in our bodies. This is why sweat also have the same concentration, it would require work to change it.
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