Who is at risk of dry eye?
Dry eye is more common in women and in people aged over 65. It is often just a symptom of getting older. This is because as you get older, your eyelids are not as effective as spreading your tears across your eyes when you blink. Also, the glands in your eyelids that produce the oily part of your tears become less effective as you get older. In some people these glands, which are called meibomian glands, can become blocked and the lids may become red and uncomfortable. This is a condition called blepharitis.
Some drugs or health problems may affect your tear film. In women, changes in hormone levels, for example during the menopause, pregnancy or while using the contraceptive pill, can increase the risk of dry eye. Your doctor or optometrist will be able to give you advice on this.
Why do my eyes feel dry, but they still water?
The tear film is made of three layers. The layer closest to your eye is called the mucin layer, and helps to stick the other tear layers to your eye. The middle layer is the watery layer, which provides moisture to the eye and helps to wash away anything that gets into the eye. It is this watery layer that increases when you cry. The outer layer of your tears is an oily layer which stops the tears from evaporating too quickly. This layer is produced by the meibomian glands in your eyelids.
The normal time for the tear film to last between blinks is over 12 seconds. If the tear film breaks up too soon, the sensitive corneal nerves on the surface of your eye may be exposed and then you will cry. This is common in the cold, the wind or if you forget to blink when you are concentrating on the computer, TV or when driving. Crying will dilute the oily layer that reduces evaporation of the tears and make your eyes feel dry again. If your eyes water a lot, you may find it helps to use a product that increases the oily layer of your tears to reduce this evaporation. Your optometrist will be able to advise you on this.