We have more than one kind of tear
Our body generates three types of tears:
The first is basal tears, which constantly lubricate, nourish and protect the cornea, a lens at the front of the eye that allows light to pass through and protects the iris, pupil and anterior chamber. Basal tears serve as a constant protective shield between the eye and the outside world, keeping dirt and particles away.
The second type is reflective tears, which are generated when the eyes need to remove harmful irritants such as smoke, foreign bodies or particles, or certain molecules in the onion that irritate the cornea. The tear glands release more of these tears than basal tears, and may contain more antibodies to help fight bacteria.
The third type of tears produced by our eyes are emotional or psychic tears, which are generated by joy, sadness, fear and other emotional states, and which some experts have claimed contain additional hormones and proteins absent in basal or reflex tears.
Thanks to @surpassinggoogle and @teardrops