Australian Science Illustrated – Issue 51 2017

Your eyes are

always tearing up

The eye is surrounded by glands, ducts, and muscles, which make

sure that tears always create the perfect lens for you to see through.

T

ears ensure sharp vision in front of your

eyes, there is always a thin membrane

of tears which cleanses the eye of dust,

producing the perfect optical surface.

The membrane is particularly maintained

by two large tear glands over the eyes. The

glands constantly produce basal tears, which

cleanse and lubricate the eyes with oil, fat, and

enzymes. When your eyes are open, the basal

tears evaporate to produce small holes in the

thin tear membrane. To fix these holes, we

simply blink every 15-20 seconds, by which the

eye is covered in a new tear membrane from

the tear glands, pushing away "used" tears.

1

A salty lachrymal
fluid with proteins,
water, slime, and oil
is produced in the tear gland
over the eye. The gland makes
about 1 ml of fluid per day,
which is "drained" to the eye.

2

The lachrymal fluid

moistens the surface

of the eye, lubricates

the eyelids, and washes away

foreign bodies. Most of the fluid

evaporates, and the rest collects

in the corner of the eye.

3

The tear ducts

collect surplus

lachrymal fluid

and carry it to the

nasolacrimal canal. It ends

up in the nostrils, from

where the tears escape.

TEAR GLAND

"DRAINS"

NASOLACRIMAL CANAL

TEAR DUCTS

NOSTRIL

BERND VOGEL/GETTY IMAGES & CLAUS LUNAU