The external structures of the eye also have roles to fulfil. Their functions are as follows:

• The eyebrows arch above the eye and protect the eyeball from trauma caused by external elements.

• The eyelids also protect the eyeball. They react when foreign bodies enter the eye, and continuous blinking distributes the tear film. When your eyelids are closed, for example when you are asleep, they maintain the right level of eye humidity and prevent light from entering. This is also the case when the eyes are exposed to strong sunlight: blinking limits the amount of light that gets into the eye and protects the retina from overexposure to sunlight and any consequences thereof.

• Like the eyebrows, the eyelashes protect the eye from foreign bodies.

• The eye's tear system is made up of a number of structures whose function is to produce and drain tears. Tears are produced by the lacrimal or tear gland and are drained away through the lacrimal point near the medial angle of the lower eyelid. The tear fluid is then discharged through the nasal sinuses.