Other names include; eye crusties, eye gunk,
sleepy dust, sleepy boogers, eye discharge, eye goop, eye crud, eye
jelly, eye crust, eye bogeys, eye boogers, eye-sand, sleepy dirt,
eye sand.
It is a type of 'rheum', which is the name for discharge from your
nose, mouth, or eyes during sleep. More specifically, eye rheum is
known as gound. Gound is made up of a mixture of dust, blood cells,
skin cells, etc., mixed with mucus secreted by the conjunctiva, as
well as an oily substance from the meibomian glands (named after
German, Heinrich Meibom).
The meibomian glands are a type of sebaceous gland that line the rim
of the eyelids with about fifty on the top and twenty five on the
bottom of each eye. They secrete an oily substance called meibum
that performs a variety of functions including: helps seal your eyes
in an air tight fashion when they are closed; prevents tears from
spilling onto your cheeks; and helps keep tears that coat your eyes
from evaporating. It is this oily substance that is one of the
primary components in gound, mixed with mucin from the conjunctiva
and various foreign particles in your eye.
Normally, when you are awake, the gound is naturally washed away via
tears and the blinking motion. As you sleep, the meibomian
secretions and other components of the gound tend to gather in the
corners of your eyes, as well as along your eye lines and dries out.
Sleepy eyes suddenly takes on a whole new meaning.