Dry eye syndrome - sometimes called keratoconjunctivitis sicca - is a condition in which the eyes can't make enough tears, or the tears evaporate too quickly. This can cause the eyes to become dry, inflamed and uncomfortable.
The most common cause of excessive tear evaporation is blockage and dysfunction of the Meibomian oil glands in the eyelids, which is also known as posterior blepharitis.
Dry eye syndrome is a common condition, with up to a third of people experiencing it at some point in their life. While anyone can develop dry eye syndrome, it's most common in people over the age of 60. The condition is also more common in women than men.
The symptoms of dry eye syndrome can be mild, moderate or severe and may include:
Dry eye syndrome is not normally serious. There are rare cases, however, when severe untreated dry eye syndrome has caused visual impairment and scarring of the eye's surface. You should therefore visit your GP as soon as possible if you have any of the following:
Please click the section headings on the right hand side of this page to find out more about the causes, diagnosis and treatment of dry eye syndrome. You can also download fact sheets and use 'Links' to access further information.
Dry eye syndrome can be caused or made worse by many things, including your environment, illnesses, side-effects of medicines, hormonal changes and simply getting older. In many cases there isn't one single, identifiable cause - it's often a mixture of things, as explained below.
We tend to take tears for granted, only noticing them if we laugh or cry. However, our eyes are always covered by a thin layer of liquid, known as a tear film. Tear production is regulated by the lacrimal functional unit, which is made up of the following parts:
If any part doesn't work properly, the whole system can break down, resulting in dry eye syndrome due to one or both of the following:
In addition, when the eyes are no longer adequately protected by the tear film, the immune system tries to compensate by sending special, infection-fighting cells to the eye. It is these cells that cause the inflammation associated with more serious cases of dry eye syndrome. As you can see below, there are a number of environmental conditions that can affect tear production and function.
Environmental factors that can have a drying effect on the eye, causing tears to evaporate too quickly, include:
People tend to blink less often when carrying out activities that require visual concentration, such as reading, writing or working with a computer. This can cause tears to evaporate faster than usual, leading to dry eyes.
Several types of medicine are thought to cause dry eye syndrome in some people. These include:
*Often used to treat high blood pressure (hypertension)
Some people experience dry eye syndrome after laser-assisted in-situ keratomileusis (LASIK) surgery, a procedure used to correct eyesight problems. However, these dry eye symptoms usually clear up after a few months.
Contact lenses can irritate the eye and cause dry eye syndrome in some people, but changing to a different type of lens - or limiting their use - will usually help to resolve the symptoms.
The hormonal changes that occur during the menopause can lead to a reduction in tear production, resulting in dry eye syndrome.
Most people with dry eye syndrome also have blepharitis, which is inflammation of the rims of the eyelids. Blepharitis is commonly associated with:
Other medical conditions that can cause dry eye syndrome in some people include:
We naturally produce fewer tears as we get older. This, combined with the effects of the menopause, probably explains why dry eye syndrome is particularly common among older women.
Your GP may make a diagnosis of dry eye syndrome by reviewing your symptoms, considering your medical history and looking at any medicines that you may be taking. An examination may also be carried out to check for other conditions and complications.
Referral to an optometrist
Following your initial consultation, your GP may refer you to an optometrist for a complete eye check-up. An optometrist will use specialist equipment to confirm whether you have dry eye syndrome and/or other conditions. Optometrists can carry out a number of specific tests, including:
Referral to an ophthalmologist
If the diagnosis of dry eye syndrome is uncertain or specialist tests and treatment are needed, your GP may refer you to an ophthalmologist. These are hospital doctors who specialise in eye disorders and surgery.
Lifestyle and environment factors
Following a diagnosis of dry eye syndrome, your doctor or optometrist will initially focus on identifying and addressing lifestyle/environmental factors that may cause or worsen dry your symptoms. These include:
A good level of daily water intake will also be encouraged to aid hydration. As omega-3 fatty acids may reduce tear evaporation and inflammation, oral supplements or dietary intake via fish or flaxseed oil is also often recommended.
Artificial tears and lubricants
The term 'artificial tears' is commonly used to describe drops, solutions and liquid gels applied directly into the eye. The term is not strictly correct, however, as artificial tears don't have all the components of real tears - they mainly just act as a lubricant. The term 'ocular lubricants' generally refers to more viscous products such as ointments. Your doctor or optometrist may recommend or prescribe artificial tears or an ocular lubricant in addition to addressing the above lifestyle and environmental factors.
Hydroxypropyl methylcellulose inserts (lacriserts) are small pellets that contain artificial tears. They are inserted under the eyelid once-daily, to help keep the surface of the eye moist. As a sustained-release formulation for artificial tears, the effect can last anywhere from 6 to 12 hours. Lacriserts are sometimes recommended when dry eye symptoms cannot be controlled by frequent use of normal artificial tears.
Some cases of dry eye syndrome can be treated using specially made glasses, known as moisture chamber spectacles. These wrap around the eyes like goggles, helping to retain moisture and protecting the eyes from irritants. Their popularity is increasing as modern designs look like sports sunglasses, unlike the more cumbersome appearance of earlier versions.
Specialist contact lenses
If regular contact lenses are causing dry eye syndrome, specially designed ones are available to help overcome the problem. Your optometrist or ophthalmologist will be able to give you more information on contact lens options.
Anti-inflammatory medicines can be used to help reduce the inflammation associated with more severe cases of dry eye syndrome. They are normally prescribed in the form of a cream or ointment. Specialist oral medications are sometimes used if products and medicines applied directly into the eyes prove unsuccessful. These oral treatments include tetracycline analogues, ciclosporin and tear secretagogues. Your doctor will provide more information on these if they are needed.
The majority of dry eye treatments do not include surgery but if they do they might include: