Man being examined for dry eye

Dry eye

What is dry eye?

Dry eye is a chronic (long-term) condition. This means that once you have had it, it can come back even after it has cleared up. It often affects both eyes, but one eye may be worse than the other.

Dry eye does not normally cause permanent problems with your sight, but in severe cases it can become very painful and cause permanent damage to the front of your eye.

Symptoms of dry eye

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.

Treatment of dry eye

Once your optometrist knows what is causing your dry eye, they can give you advice on how to manage it. There are four main ways to help your dry eye:

1. Avoid using make-up and keep your eyelids clean
Eyeliner, particularly when put on the rim of your eyelid, may block the meibomian glands that produce the oily part of your tear film. This may cause the area around your eyes to be inflamed. It is also important to make sure you keep your eyelids clean, particularly if you have blepharitis.

2. Be aware of your environment
There are some environments that may make your eyes feel more dry. High temperatures and central heating may increase the evaporation of your tears and make your eyes feel more dry, as can draughts and air conditioning.

You may find it helpful to reduce the temperature of your central heating at home and try to avoid draughts near your face, for example by directing car air vents away from you face. Some people find using a humidifier to put more water into the air may help slow down the evaporation of tears.

If you are out on a windy day you may find it useful to wear glasses or sunglasses (ideally the wraparound type)to protect your eyes from the wind. Try to avoid smoky atmospheres as these may irritate your eyes.

3. Use eye lubricants
There are several types of eye lubricants available. Most of these aim to lubricate your eyes by giving you extra moisture. They are available as drops, gels or ointment, and most are available without a prescription. If you find the drops wash out of your eye too quickly you may find the gel-type better as they are thicker and so stay in your eye longer.

Ointment is generally used for people whose eyes dry out at night because they do not fully close their eyes. Ointments are usually only used at night because they are sticky and can cause blurry vision.

Eye lubricants do not contain any drugs and so you can use them as often as you like. However, some contain preservatives which may make your eyes sore. If you are using them more than six times a day you should use preservative-free drops.

If your dry eye is caused by your tears evaporating too quickly, you may find it helpful to use a spray rather than artificial tear drops. These sprays aim to replenish the oily layer of your tears and stop them evaporating as quickly. They are available without prescription and are sprayed onto the edges of your eyelids when your eyes are closed. When you open your eyes the solution spreads across the surface of your eye, creating a new oily film.

4. Have treatment to stop the tears draining away
Your tears drain away into your nose through four small drainage channels in your eyelids (one in each of the upper and lower lids). Small plugs, called punctum plugs, can be put into the holes in your lower eyelids to stop the tears draining away and help the tears to stay in your eye for longer. The plugs can be easily removed if necessary. Your optometrist will be able to give you advice on this.

Using a computer

Some people find that their eyes feel dry while they are looking at a computer screen (or afterwards). There is no evidence that looking at a computer screen does your eyes any harm, but it may make you blink less often. We recommend that when you use a computer you make sure you blink often and try and look away from the screen regularly, just for a few seconds, to give your eyes a rest.