Dry eye syndrome, which is also known as keratoconjunctivitis sicca, is a condition where the eyes do not make enough tears, or the tears evaporate too quickly. This can lead to the eyes drying out and becoming inflamed (red and swollen).
The symptoms of dry eye syndrome can be mild or severe. They include:
- dry or sore eyes
- blurred vision
How common is dry eye syndrome?
Dry eye syndrome is a common condition, although estimates of how many people are affected by the condition vary. The condition tends to affect people above 60, and it is more common in women than men.
Around one in 13 people who are in their fifties experience dry eye syndrome, and the condition becomes more common with age. Up to a third of people age 65 or older may have dry eye syndrome.
Dry eye syndrome is not usually a serious condition. A number of steps can be taken to relieve the symptoms.
Dry eye syndrome may be slightly painful, but it should not affect vision. However, there are rare cases where severe untreated dry eye syndrome has caused visual impairment and scarring of the eye's surface.
The symptoms of dry eye syndrome usually affect both eyes and may include:
- feelings of dryness, grittiness or soreness, which get worse throughout the day
- redness of the eyes
- watering eyes, particularly when exposed to wind
- eyelids that stick together when you wake up
These symptoms may get worse in smoky or hot environments.
Dry eye syndrome can cause complications, such as:
- scarring of your cornea (the transparent layer at the front of the eye)
- conjunctivitis - inflammation (swelling and redness) of the conjunctiva (the transparent layer of cells that cover the white part of your eyeball and the inner surfaces of your eyelids)
See Dry eye syndrome - complications for more information about these conditions.
Such complications can produce more severe symptoms, for example:
- extreme sensitivity to light (photophobia)
- very red eyes
- very painful eyes
- a deterioration in your vision
Contact your GP immediately if you have any of these symptoms. If this is not possible, visit your nearest accident and emergency (A&E) department.
Do not ignore the severe symptoms that are listed above. If left untreated, the complications from dry eye syndrome could affect your sight permanently.
Dry eye syndrome can have many different causes, including:
- environmental factors, such as a hot or windy climate
- side effects of medicines
- hormonal changes
However, in many cases of dry eye syndrome there is no single identifiable cause.
The importance of tears
You often only notice your tears when something happens that makes you laugh or cry. However, your eyes are always covered by a thin layer of liquid, known as a tear film (see box to the left).
Tears are produced and regulated by a system known as the lacrimal functional unit.
Lacrimal functional unit
The lacrimal functional unit describes the system of different parts of the body that work together to regulate the production of tears.
The lacrimal functional unit is made up of a number of different parts, which are described below.
- The lacrimal gland produces a liquid substance that makes up the majority of your tears.
- The Meibomian glands produce a fatty liquid that makes up the outer layer of the tear film.
- The eyelid spreads tears across the surface of your eye when you blink.
- The cornea is the clear layer at the front of your eye that contains smaller glands, which also produce some of the liquid that makes up your tears.
- The tear ducts are two small channels at the side of your eye that allow your tears to drain into your nose.
If any part of the lacrimal functional unit is affected, the whole system can break down, resulting in one of two outcomes, or possibly both:
- the quantity of tears is affected - the body does not produce enough.
- the quality of the tears is affected - the tears evaporate before the body has a chance to replace them.
Either outcome can cause dry eye syndrome.
Also, as the eyes are no longer adequately protected by the tear film, the immune system (the body's defence system) tries to compensate by sending special, infection-fighting cells to the eye. It is these cells that cause the inflammation (redness and swelling) of the eye, which is associated with more serious cases of dry eye syndrome.
A number of factors can interfere with the lacrimal functional unit. These are explained in more detail below.
Hormones and the nervous system
Hormones (powerful chemicals that are produced by the body) and the nervous system (your nerves, brain and spinal cord) play an important part in tear production.
Hormones stimulate the production of tears. The changes that occur in hormone levels during the menopause (when a woman's periods stop) may explain why older women are more susceptible to dry eye syndrome.
The nervous system can trigger an increase in tear production, often as a way of protecting your eyes from potentially harmful substances. This is why, for example, your eyes water if you are exposed to smoke.
Environmental factors can have a drying effect on your eyes, causing your tears to evaporate. These factors include:
- dry climate
- hot blowing air
- high altitude
Regular exposure to these environmental factors can cause dry eye syndrome. People are particularly at risk when they are exposed to a combination of environmental factors. For example, the combination of a dry climate and warm air conditioning, found in many offices, can cause dry eye syndrome in some people.
When you are carrying out an activity that requires visual concentration, such as reading, writing or working with a computer, you tend to blink less frequently. This can cause your tears to evaporate and lead to dry eye syndrome.
Several medicines are thought to cause dry eye syndrome in some people. These include:
Beta-blockers and diuretics are often used to treat high blood pressure (hypertension).
Some people who have had laser-assisted in-situ keratomileuis (LASIK) surgery find that they have dry eye syndrome in the weeks after surgery. However, the symptoms usually clear up after a few months.
Sometimes, contact lenses irritate the eye and cause dry eye syndrome. Changing to a different type of lens, or limiting their use, usually help to resolve the symptoms.
Most people with dry eye syndrome also have blepharitis (inflammation of the rims of the eyelids). Blepharitis is commonly associated with:
- seborrhoeic dermatitis - a common skin condition that is often referred to as seborrhoeic eczema
- rosacea- a common yet poorly understood chronic (long-term) skin condition that mainly affects the face
Other medical conditions that can cause dry eye syndrome in some people include:
- contact dermatitis (eczema) - a condition that causes inflammation of the skin
- allergic conjunctivitis- inflammation of the conjunctiva (the transparent layer of cells that covers the white part of the eyeball and the inner surfaces of the eyelids)
Less commonly, dry eye syndrome can be caused by a number of other conditions:
- Sjögren's syndrome- a condition that causes excessive dryness of the eyes, mouth and vagina
- rheumatoid arthritis - a condition that causes pain, swelling and inflammation in the joints
- lupus- a condition where your immune system attacks healthy body tissue
- scleroderma - a skin condition that can also affect the blood vessels
- previous trauma (serious injury) - such as burns or exposure to radiation
- shingles - an infection of a nerve and the area of skin around it, caused by the herpes varicella-zoster virus
- Bell's palsy- a condition that causes weakness or paralysis to the muscles of one side of the face
- HIV - a virus that attacks the body's immune system
As you get older, you produce fewer tears. This, combined with the effects of the menopause, probably explains why dry eye syndrome is common among older women.
Your eyes are always covered by a thin layer of liquid, known as a tear film.
This liquid is made from of a mix of:
- infection-fighting cells
Your tears serve several important functions:
- they lubricate your eye, keeping it clean and free of dust
- they protect your eye against infection
- they aid sight by helping to stabilise your vision
Your GP should be able to diagnose dry eye syndrome by looking at your symptoms and your medical history. They may examine you to check for other conditions and complications.
Tell your GP about any symptoms that you have, not just ones that affect your eyes, as you may have another medical condition as well.
Your GP will also want to know about:
- any medicines that you are taking
- your personal circumstances - for example, if you work on a computer all day
These may hep your GP identify a possible cause of your dry eye syndrome.
Referral to an optometrist
Your GP may refer you to an optometrist for a check-up. Optometrists are trained to recognise sight defects and eye conditions. Although your GP may refer you to an optometrist, they are private practitioners and charge for their services.
Your optometrist will use special equipment to examine your eye, and will be able to confirm whether you have dry eye syndrome and any other associated conditions and complications. They can also give you advice about treatment.
There are a number of tests that your optometrist can carry out in order to assess the quality and quantity of your tears. Two of these tests are described below.
The Schirmer test
In this test, small strips of blotting paper are placed under your eyelid. After five minutes, the strips are removed and studied in order to determine how wet the paper is.
The Rose Bengal test
In this test, a non-toxic dye, known as Royal Bengal, is dropped on the surface of your eye. The distinctive red colour of the dye allows the ophthalmologist to see how well your tear film is functioning and how long it takes for your tears to evaporate.
Referral to an ophthalmologist
If the diagnosis is uncertain, or specialist tests and treatment are needed, your GP may refer you to an ophthalmologist. Ophthalmologists are doctors who specialise in eye conditions. Like optometrists, they use special equipment and techniques to examine the eye.
Once dry eye syndrome develops, some people have recurring episodes for the rest of their lives.
There is no cure for dry eye syndrome, but a range of treatments can control your symptoms. In rare cases, more severe cases of dry eye syndrome may require surgery.
Underlying medical conditions
If you have an underlying medical condition that is causing dry eye syndrome, your GP will prescribe treatment for it.
Most people with dry eye syndrome also have blepharitis, which is a common and usually mild condition that causes inflammation (redness and swelling) of the rims of the eyelids. Treatment for blepharitis is based on good eye hygiene. See Dry eye syndrome - self care for more information.
See the Health A-Z: blepharitis for more information about the condition.
If your underlying condition is a complex one, such as HIV or lupus, you will need to be referred to a specialist for treatment if you are not already receiving treatment for the condition.
Different types of medicines can also be prescribed as necessary.
To treat your dry eye syndrome, the specialist will address any possible triggers of the condition, such as medicines or environmental factors, before trying to eliminate them.
It is possible to make changes to compensate for environmental factors. For example, placing a humidifier in your home to reduce dryness, or changing your work habits to rest your eyes.
See Dry eye syndrome - self care for more details about the changes that you can make. If these measures are not successful, there are a number of other treatments that can be tried. These are described below.
Mild to moderate cases of dry eye syndrome can usually be successfully treated using eye drops that contain 'tear substitutes', a liquid that is designed to mimic the properties of tears. These eye drops are available without a prescription over-the-counter (OTC) from a pharmacy.
There are many different types of eye drops, so you can switch if your original choice does not work.
Some eye drops contain a preservative to prevent harmful bacteria from growing inside the medicine. If you have severe symptoms and you need to use these eye drops more than six times a day, use preservative-free eye drops.
This is because the preservative can sometimes irritate your eye. Your GP or pharmacist will be able to advise you about an alternative. If you wear soft contact lenses, you may also need to use a tear substitute that is preservative-free. Preservative-free eye drops may be more expensive.
Eye ointment can also be used to help lubricate your eyes. However, it can often cause blurred vision, so it is probably best to use it last thing at night.
If you wear contact lenses, do not use eye ointments that contain paraffin. Ask your pharmacist or GP for advice about which ointments may be suitable for you.
Some cases of dry eye syndrome can be treated using specialist eyeware. These include specially made glasses called moisture chamber spectacles. These wrap around your eyes like goggles, helping to retain moisture and protecting your eyes from irritants.
Moisture chamber spectacles used to be unpopular because they had a strange design and people were embarrassed to wear them. However, they are now becoming a more popular treatment option because the modern designs look like sports sunglasses.
If your previous contact lenses were causing dry eye syndrome, specially designed contact lenses are also available.
If your dry eyes fail to respond to other forms of treatment, surgery may be an option. Two potential types of surgery are described below.
One surgical technique, known as punctal occlusion, involves using small plugs, called punctual plugs, to seal your tear ducts. This means that your tears will not drain into the tear ducts, and your eyes should remain moist.
Temporary plugs that are made of silicone are normally used first to determine whether the operation has a positive effect. If it does, more permanent plugs can replace the silicone ones.
Salivary gland autotransplantation
Another surgical technique for treating very severe dry eye syndrome is known as salivary gland autotransplantation. This procedure is usually only recommended after all other treatment options have been tried.
Salivary gland autotransplantation involves removing from your lower lip some of the glands that produce saliva, and placing or grafting them into the side of your eyes. The saliva that is produced by the glands acts as a substitute for tears.
Ulceration of the cornea
In severe cases of untreated dry eye syndrome, the associated inflammation (redness and swelling) can damage the surface of the cornea (the transparent layer at the front of the eye). This is called keratitis.
Keratitis can lead to scarring (ulceration), which could result in some disruption of your vision.
Conjunctivitis is inflammation of the conjunctiva (the transparent layer of cells that covers the white part of the eyeball and the inner surfaces of the eyelids)
Most cases of conjunctivitis that are caused by dry eye syndrome are mild and do not need specific treatment. However, if you have conjunctivitis that becomes severe and chronic (long-term), seek treatment advice from a specialist.
There are several self-care techniques that can be used to help prevent or reduce the symptoms of dry eye syndrome.
Keep your eyes clean
Good eye hygiene will help prevent dry eye syndrome and the associated condition of blepharitis, which is inflammation (redness and swelling) of the rims of the eyelids.
To clean your eyes:
- wet a cloth with warm water and hold it against your closed eyes for five to ten minutes
- massage your eyes by gently rolling your first finger over them in a circular motion - this will help to push out any of the mucus-like fluid from the tiny eyelid glands
- gently clean your eyelids using cotton wool and hot (but not boiling) water - a cotton bud can also be used to clean your upper and lower eyelid and remove any crustiness
See the Health A-Z topic about Blepharitis - treatment for more information about treating this condition.
Protect your eyes
Certain environments can irritate your eyes. Keep your eyes protected eyes from:
- hot air
Wraparound glasses may provide good protection. Avoid smoky environments and, if you smoke, try to quit.
Adjust your computer
Make sure that your computer workstation is positioned correctly in order to minimise eye strain. Most companies have a health and safety officer or representative who can advise you about this. Your monitor (screen) should stand at eye level or just below it.
If you use a computer, make sure that you take enough breaks away from your computer screen, and blink your eyes regularly. Taking breaks every hour to rest your eyes may help to reduce your symptoms.
Use a humidifier
A humidifier at work and at home will moisten the surrounding air. If you cannot afford a humidifier, lightly spray your curtains with water several times a day to help keep the air moist.
Open the windows for a few minutes on cold days, and for longer in the spring and summer. This will also help to keep the air moist and prevent the build-up of mould.
There is evidence to suggest that a diet high in omega-3 fats can help to prevent dry eye syndrome. The exact reasons for this are unclear, but it is known that omega-3 fats are used in the production of tears.
The best source of omega-3 fats are oily fish such as:
- fresh tuna (not canned because the canning process removes the beneficial oils)
Aim to eat at least two portions of fish a week, one of which should be oily fish.