Everybody at some point in their life has woken up with little crusty particles in the corner of the eyes. The dry little particles are formed at the corners of the eye typically and can be brushed away. The official term for these dry particles is Rheum. It is made up of natural mucus from the eye and nose, skin cells, dust and pollen. These are totally normal and a natural part of your body's function to flush away foreign objects from the eyes. The funny part is that there doesn't seem to be a universal, everyday term for Rheum. Eye boogers, the sandman's dust, sleepies, crusties and a multitude of other names are said on a daily basis. Admittedly, these common terms roll off the tongue a little better, even if they are a bit silly.
Trying to one of our optometrists to say "eye booger" was one of my highlights today.
There generally shouldn't be any cause for concern with Rheum. You should tell your optometrist only if you notice that there is discoloration, pus or if your eyes are "glued" shut in the morning. That is usually a signal there is a problem with the eye and it should be looked at by an optometrist.