Dry Eye

Dry eye is a common condition that may be caused because

your eyes do not produce enough tears, or because the tears that you have evaporate too quickly or do not spread evenly across the front or your eyes.

Dry eye can make your eye feel scratchy or irritated.  In severe cases it may temporarily make your vision blurry.  It can be uncomfortable, but rarely causes serious eye damage.



Who is at risk of dry eye?

Dry eye is more common in woman and in people aged over 65.  As we get older, our eyelids are less effective at spreading tears across the eyes as we blink and the tears that we produce may be of a poorer quality.

Some drugs or health problems may also affect your tear film.  In woman, changes in hormone levels, for example during the menopause, pregnancy or while using the contraceptive pill, can increase the risk of dry eye.

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 wash away anything that gets in to the eye.  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 tear film will usually last for over 12 seconds between blinks.  If the tear film breaks up more quickly, it will expose sensitive corneal nerves on the surface of you eye, causing the eye to produce reflex tears and water.  This is common in the cold, the wind or if you forget to blink when you are concentrating on the computer or tv.  These extra, watery tears dilute the oily layer, increasing evaporation and making your eyes feel dry again.

If your eyes water a lot, you may find it useful to use artificial tears that increase the oily layer of your tears.

What can I do about dry eye?