Question: Why do we blink???

Michael Kelly answered on 20 Jun 2014:

Blinking maintains the layer of tears on the surface of the eye and protects the front surface.

Your tears are composed of three further layers, a mucus layer secreted by the tissues on the white of the eye, a watery phase secreted by the lacrimal gland under the upper outer edge of the bony orbit of the eye, and an oily layer secreted by the edges of your eyelids. When you close your eye during the blink the edge of the eyelid resting on the eye rubs the mucus into the surface and gathers it up, there is a small increase in the watery secretions and the oily layer is squashed up. A contraction in the eyelid margin causes the drains at the corner of your eye near your nose to open and suck out the excess tears. On the opening part of the blink the mucus is smoothed and spread out, the oily film re-establishes itself from when your eyelids touched.

At the same time the eyes are rolling upwards, this called Bell’s reflex. The overall effect is to protect the clear part of the eye, the cornea. Behind the cornea is the iris and the pupil, the coloured part of people’s eyes and the central black hole.