So let's look at the eye in more detail, starting with its external appearance.

The sclera - the white of the eye - is a firm fibrous membrane that forms the outermost layer of the eyeball. It maintains the shape of the eye and gives attachment to the muscles that move the eye.

Two folds of tissue, one above and one below the eye, form the eyelids, which join at the inner and outer canthus. The eyelids move towards each other during blinking, spreading tears over the cornea to keep it clean and clear.