What is dry eye?
The surface of our eyes is coated with a thin film of tears called the tear film. The tear film helps lubricate the eyes, prevents them from drying out and gives protection from bacteria and environmental irritants such as dust. We need to have a healthy tear film in order to keep our eyes comfortable and to maintain good vision.
Dry eye is a disorder of the normal tear film that results from either of the following:
- Decreased tear production
- Excessive tear evaporation
What are the causes of dry eye?
- Reasons why we produce fewer tears include:
- Age – we naturally produce fewer tears as we get older.
- Hormonal changes – particularly common in postmenopausal women.
- Some medications – side effects of medications such as antihistamines, antidepressants, beta-blockers and oral contraceptives
- Sjögren’s syndrome- A relatively uncommon but often more troublesome form of dry eye is associated with rheumatoid arthritis and is called Sjögren’s syndrome. Sjögren’s syndrome attacks the body’s lubricating glands, such as the tear and salivary glands.
- Reasons tears evaporate quickly
- A disturbance in the production of the outer layer of the tear film – the main purpose of the outer layer of the tear film is to slow down the evaporation of tears. Certain conditions of the eyelids such as meibomian gland disease, blepharitis and rosacea can lead to poorer quality tear film which evaporates more quickly.
- If blinking is decreased – Tears can evaporate from the front of our eyes quicker than normal when we blink less or do not close our eyes properly between blinks. Watching TV, computer work or reading requires prolonged periods of concentration and we tend to blink less during these periods.
- Certain conditions such as Bell’s Palsy, thyroid eye disease or stroke can make it difficult for the eyelids to close completely when blinking.
Dry eye can be aggravated by a number of factors
- Reading and watching TV for prolonged periods
- Computer use
- Heating and air conditioning
- Exposure to dust and allergens
- Hot, dry or windy environments
- Contact lens use
- Laser eye surgery
What are the signs and symptoms?
Symptoms of dry eye can vary greatly from one person to another and often these symptoms increase throughout the course of the day. The most commonly reported symptoms are;
- Tired eyes
- Stringy mucus around the eyes (particularly on waking)
Changes in vision may occur such as:
- Increased sensitivity to light
- Blurred vision
- Difficulty detecting changes in contrast
Are there any tests or examinations needed to confirm the diagnosis?
A diagnosis of dry eye can often be made by an eye care specialist just by hearing about the eye symptoms you are suffering. However, an eye examination is often necessary in order to look for any signs of inflammation and to examine the quantity and quality of your tear film.
The following routine tests may be performed as part of your eye examination:
• An examination of the front of your eyes using a specially designed microscope called a ‘slit-lamp’. This test will examine the surface of the eye for dryness and inflammation, and the eyelids for any signs of inflammation or infection.
• Eye drops containing special dyes may be put into your eyes to reveal distinctive patterns on the eye surface. The patterns show the areas of the surface on your eye which are not protected by the tear film and which may have been damaged by inflammation.
• A test called a ‘Schirmer’s Tear Test’ may be performed to measure the amount of tears you are producing. A small strip of filter paper is placed just inside the lower eyelid and left in place for one minute. After that time the strip is removed and the amount of wetting measured.
What treatments are available?
Although there currently is no cure for dry eye, there are several treatments available to help make the eyes more comfortable, to maintain vision and to prevent damage to the tissues on the surface of the eye.
Artificial tear supplements
The most common type of treatment for patients with dry eye is the use of eye drops known as ‘artificial tears’ or artificial tear supplements’. These eye drops do not treat the causes of dry eye; they only relieve the symptoms, but people with mild or moderate dry eye often find that using artificial tears alone is enough to keep their eyes comfortable.
Sometimes, in severe cases of dry eye, these openings can be permanently closed using cautery or laser. This procedure accomplishes the same thing as the punctal plugs, but cannot be reversed once it has been performed.
Treatment of underlying causes
Your eye specialist will try to determine the cause of your dry eye symptoms eg blepharitis, or inflammation of the eyelids in order to give you the most appropriate advice and treatment.
Risks and side effects
While symptoms of dry eye can be irritating, for the vast majority of people no long-term vision loss is expected. Patients with severe dry eyes are more at risk of infection, ulceration and thinning of the surface of the eye. These conditions can cause permanent damage to the vision.
What can you do to help yourself at home?
Proper hydration, breaks in front of monitors, applying cool packs over your eyes , a healthy diet and anything you can do to help avoid your eyes from drying out may help improve your symptoms and alleviate discomfort.
The following suggestions may be of use:
Central heating in the winter months and air conditioning in the summer months decrease the humidity in the air. Try to boost the air humidity of the rooms you live and work in by placing bowls of water around the room to evaporate.
Excessive air movement can dry out eyes. Decrease the speed of any air movement indoors by slowing down any ceiling fans or oscillating fans. Avoid sitting beneath air ducts, or directly in front of car heater fans. Try to avoid going out in very windy conditions.
Large amounts of dust in the air may increase the symptoms of dry eye. An air filter in indoor conditions might be helpful.
If contact lenses increase your discomfort, mention it to your optometrist or contact lens practitioner. They may be able to suggest changes to your wearing times or modify the type of contact lens to improve your symptoms.
Use the artificial tear drops and lubricant ointments that provide you with the most relief from your symptoms.
When watching TV or reading, try to make a conscious effort to blink more often. Closing and opening your eyelids will replenish the tear film over the front of your eyes. Closing the eyes for ten seconds every five to ten minutes may also make a difference to your levels of comfort.
Frequently asked questions.
Which artificial tear treatment is the best for me?
There are different formulations.The answer is, to try several and find the type or combination of types that suits you the best.
Why do I have dry eye despite the fact that my eyes are watering?
The make up of tears and the correct balance between the layers of the tear film is critical to their efficiency. If the mix of tear ingredients is wrong they will not work properly and will give the symptoms of dry eye. There are basic tear secretions and reflex tear secretions. Your everyday basic tear production may be so poor and your eyes so uncomfortable that the reflex tear production may flood the eyes with watery tears.