 | What is Dry Eye |  | What is Dry Eye
If you have sandy, gritty irritated eyes or burning eyes and these symptoms get worse as the day goes on, you're probably one of the millions of people with a problem called "dry eye". Dry eye's prevalence increases with age, so that it is extremely common in older people of both sexes. The condition affects two-to-three times more women than men. Millions of people have moderate or severe symptoms of the disease and scientists estimate that 20 times as many have mild cases of dry eye. Now, after years of research, the good news is that we finally understand dry eye and there is something you can do about it. |  | What is it?
Dry eye (also called dry eye syndrome) is a very common condition. Dry eye occurs when people don't have either enough tears, or the correct composition of tears, on the surface of their eyes to lubricate the eyes and keep them comfortable.
- The outer, oily, lipid layer of the tear film is produced by the meibomian glands in the eyelids and reduces evaporation of the tears.
- The thick, middle, watery (aqueous) layer is made by the lacrimal gland above the upper eyelid and washes away irritants.
- The inner, mucus layer is secreted by the goblet cells in the conjunctiva of the eyelids and helps the tear film stick to the cornea.
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| | All three components of the tear film are important and necessary for the eye to maintain a normal healthy environment. The balance of the tear film components can change in certain situations. If this occurs, environmental factors may become more important as causes of uncomfortable, dry feeling eyes. |
| Why is the eye covered by tears?
It's because the delicate living tissue on the surface of your eye has no blood supply - it has a tear supply instead. So rather than getting important things like oxygen and electrolytes from the blood, your eye surface gets them from the watery layer of your tears. In dry eye the tear film on the eye surface loses water because of either decreased tear production or increased evaporation. And as evaporation continues throughout the day, your eyes feel drier and drier. |
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