Eyelids are there to protect the eye from external stimuli, such as dust, wind or smoke. In addition, they spread tear fluid on the surface of the eye and limit the amount of light entering the eye.
The eyelid may turn inward so that the eyelashes rub on the cornea, a condition called entropion. This causes a foreign body sensation and watering or even inflammation of the eye. Entropion typically affects the lower eyelid and is associated with decreased elasticity of the skin. It may also be due to trauma.
As first aid, tape can be applied to turn the lower lid outward to its normal position. Nevertheless, surgical treatment will ultimately be needed.
Ectropion, or outward turning of the eyelid, is another age-related phenomenon. It causes lacrimation, or tear flow, and the conjunctiva often becomes dry, thickened and inflamed. Malposition of the lower lid may also be due to a tumour, prolonged inflammation or various types of scars from injuries. Eye drops moisturizing the surface of the eye, ointments and a watch glass can be used for first aid, as necessary.