Dry Eye Syndrome
What is Dry Eye Syndrome?
Dry eye syndrome (also known as dry eyes or keratoconjunctivitis sicca, KCS) is a very common condition that is caused by a disturbance of the tear film. This abnormality may result in disruption of the ocular surface, causing a variety of symptoms that interfere with quality of life.
A thin tear film coating the eye is made up of three layers: the innermost mucous layer, the middle watery layer, and the outermost oil layer. Any disturbance in the balance of the components will lead to dry eye syndrome.
What causes Dry Eye Syndrome?
Dry eye syndrome is a common disorder of the normal tear film that results from decreased tear production, excessive tear evaporation, and an abnormality in the production of mucus or oil normally found in the tear layer, or a combination of these.
- Watery (aqueous) tear deficiency is caused by either poor production of watery tears or excessive evaporation of the watery tear layer. Poor production of tears by the tear glands may be a result of age, hormonal changes, or various autoimmune diseases, such as Sjögren's syndrome, rheumatoid arthritis, or lupus. Evaporative loss of the watery tear layer is usually a result of an insufficient overlying lipid layer. Some medications, such as antihistamines, antidepressants, beta-blockers, and oral contraceptives, may decrease tear production. If blinking is decreased or if the eyelids cannot be closed, the eyes may dry out because of tear evaporation. While reading, watching TV, or performing a task that requires close attention with the eyes, a person may not blink as often. This decreased blinking allows excessive evaporation of the tears. Certain conditions, such as stroke or Bell's palsy, make it difficult to close the eyes. As a result, the eyes may become dry from tear evaporation. Parkinson’s disease can decrease blink rate causing evaporative dry eyes.
- Mucus (mucin) tear deficiency occurs in the conjunctiva. This can result from chemical (alkali) burns to the eye or because of different autoimmune diseases, such as Stevens-Johnson syndrome and cicatricial pemphigoid. This abnormal production leads to poor spreading of the tears over the surface of the eye. The surface of the eye can dry out and even become damaged, even though more than enough watery tears may be present.
- Oil (lipid) tear deficiency is the result of meibomian (oil) gland dysfunction, rosacea, or following oral isotretinoin medication. Meibomian glands are the oil glands in the eyelids (with opening along the lash lines) that produce the lipid (oil) layer.
What are the dry eye syndrome symptoms?
Common symptoms are gritty/scratchy, or filmy feeling, burning or itching, redness of the eyes (conjunctivitis), blurred vision, foreign body sensation, and light sensitivity. The symptoms are worse towards the end of the day, in dry or windy climates, and in winter months.
How is dry eye syndrome diagnosed?
During an eye examination, the eye doctor will most likely be able to diagnose dry eye syndrome just by hearing the patient's complaints about his or her eyes. Confirmation of the diagnosis can be made by seeing signs of dry eyes. As part of the eye examination, the following tests may be performed:
- The front of the eyes is examined using a special microscope, called a slit lamp.
- The amount and thickness of the tear film are inspected.
- The stability of the tear film is assessed by checking the tear breakup time.
- The conjunctiva is examined to determine if it is too dry.
- The cornea is checked to see if it has dried out or become damaged.
How is Dry Eye Treated?
There is no cure for dry eye syndrome and some people have recurring episodes for the rest of their lives, but there are treatments to help control the symptoms. The exact treatment for dry eye syndrome depends on whether symptoms are caused by the decreased production of tears, tears that evaporate too quickly, or an underlying condition.
- The first thing to consider is whether there are any obvious factors that could be changed, such as altering any medication that is causing symptoms.
- If your dry eye syndrome is caused by an underlying medical condition, your medical doctor will prescribe treatment for it or will refer you to an appropriate specialist.
- You may also be able to help prevent dry eye syndrome or ease your symptoms by adjusting your environment, keeping your eyes clean and improving your diet. Read more about treating and preventing dry eye syndrome below for specific treatment.
- Mild cases of dry eye syndrome can usually be treated using lubricant eye treatments that consist of a range of drops, gels and ointments. These lubricants are often called 'artificial tears' because they replace the missing water in the tear film. However, they do not contain the antibodies, vitamins and nutrients found in normal tears that are essential for eye health.
- Moderate cases require more frequent use of artificial tears or thicker eye drops (gels). There are many different types of eye drops and gels, and it is often worth trying a number of different ones to find one that suits you. However, it is important you discuss any changes you wish to make to your treatment with your doctor.
- Severe cases need frequent use of lubricants, more than 4-6 times a day. Preservative-free eye drops are more suitable because they do not contain preservatives that irritate the eyes with frequent use. If you wear soft contact lenses, you may also need to use a lubricant that is preservative-free, as preservatives attach to the contact lens and damage the eye. These types of eye drops may be more expensive.
- 'Oily' tear eye drops replenish the oily part of the tear film and reduce evaporation from the surface of the eye. Oily tear drops are particularly useful if you have blepharitis (inflammation of the rims of the eyelids) or dry eye syndrome caused by your tears evaporating too quickly.
- Eye ointments can also be used to help lubricate your eyes and help keep them moist overnight because your tears can evaporate while you sleep if your eyes are not fully closed. These ointments tend to be used overnight because they can cause blurred vision. If you wear contact lenses, do not use eye ointments while wearing them.
The underlying problem with long-term dry eye syndrome is inflammation in and around the eye. Therefore, one of the anti-inflammatory treatments mentioned below may also be recommended.
-Corticosteroid Eye Drops and Ointments
Corticosteroids are powerful anti-inflammatory medications that can be given as eye drops or ointments in severe cases of dry eye syndrome. They have side effects such as cataract formation and raising the pressure within the eye in about one in every five people. This group of treatments should only be used if you are being monitored by an eye doctor. Common steroids in these groups are prednisolone acetate 1%, Lotemax, Tobradex.
Low doses of a medication called tetracycline can be used as an anti-inflammatory agent for a minimum of three to four months, sometimes much longer. The most common tetracycline used is doxycycline.
-Cyclosporine (Restasis) Eye Drops
Cyclosporine is a medication that suppresses the activity of your immune system and is commonly used in the treatment of dry eye syndrome. The commercially available form of prescription cyclosporine eye drop is called Restasis. It is used twice a day and requires up to 3 months to see improvement in dry eye symptoms.
-Autologous Serum Eye Drops
In very rare cases, where all other medications have not worked, autologous serum eye drops may be required. Special eye drops are made using components of your own blood. It is only available through a local compounding pharmacy. To make autologous serum eye drops, one unit of blood is taken under sterile conditions (as for regular blood donation). The blood cells are then removed and the remaining serum is put into eye drop bottles. Because of quality standards, this process can take several days before the treatment is finally available to use.
Punctal occlusion involves using small soft plugs called punctal plugs to seal your tear ducts. This means your tears will not drain into the tear ducts and your eyes should remain moist. In more severe cases, the tear ducts are cauterized (sealed using heat). This permanently seals the drainage hole to increase the amount of tears on the surface. This can be performed in combination with lubrication treatment.