Dry eye is a sore, gritty sensation caused by not enough tears being produced or something affecting the quality of tears to form a protective tear film.
Dry eye is common with ageing and is more common in women than men. It is associated with some conditions and medications, and with computer use (not blinking enough).
Tears are made up of three separate secretions: a sticky base layer, a watery mid layer and an oily top layer (which slows tear evaporation). Dry eye is a sore, gritty sensation caused by too little tear production or poor quality tears that form an inadequate film.
Normally tears form a protective film over the surface of the eye, lubricating movement and washing away debris and any toxins. Dry eye can be painful and cause sensitivity to bright light or open air and wind.
Despite the name, the irritation of dry eye may trigger excessive tears. Dry eye may also redden the eyes, but it requires different treatment from allergic conjunctivitis(external link) and 'red eye'.