Dry eye is a sore, gritty sensation caused by something affecting the quality of tears or the amount of tears being produced which affects the protective film on your eyes. The gritty sensation may be accompanied by pain, redness and vision problems. It may cause sensitivity to bright light or open air and wind.
Dry eyes are common as we get older, and are more common in women than men. It's associated with some conditions and medications, and with computer use (not blinking enough). It generally affects both eyes.
Tears are made up of 3 separate secretions – a sticky base layer, a watery mid layer and an oily top layer (which slows the evaporation of your tears). Normally tears form a protective film over the surface of the eye, lubricating movement and washing away debris and harmful material.
Despite the name, the irritation of dry eye may trigger excessive tears. Dry eye may also redden the eyes, but it's not the same as allergic conjunctivitis or 'red eye'.