Eye dryness (xeropthalmia) is a common occurrence that most of us will experience many times in life. It is usually not a persistent problem and often self-resolves with blinking a few times or changing environment. However, with the rise in computer use in the workplace, dry eyes has become a common symptom that is more than not just an inconvenience. For some people eye dryness may be persistent and even lead to complications such as eye infections. In many of these cases eye dryness is a symptom of some underlying disease.
Dry Eyes vs Low Tears
Tears are a relatively complex secretion that keeps the eyes moist and protects the eye tissue against infection. It is made up of several components which form three layers, each of which is secreted by different glands. Excessive tearing is common when we yawn, are tired or with strong emotions like sorrow or even joy. Insufficient tear production or imbalances in the composition of tears can lead to dry eyes. However, there are other factors that can speed up drying of the eyes even when tear production and composition is relatively normal.
Once the tears are secreted it stays on the eye surface for a short period of time. Some of it is evaporated into the atmosphere and the excess is drained out of the eyes into the nose through the nasolacrimal duct. Tear secretion and drainage is an ongoing process and abnormally excessive drainage of the tears can contribute to dry eyes even when tear production is normal.
Causes of Eye Dryness
Tears are made up of oils, water with electrolytes and other substances and mucus. These different components form layers with the oily layer being on the outermost surface in contact with the environment and the mucus layer in contact with the eye surface. The lacrimal glands (tear glands) produce the watery layer with electrolytes, antibodies, proteins and other substances. The oily layer is produced by the Meibomian glands and the mucus layer is produced goblets cells of the conjunctiva. If even one layer of the tears is abnormal then there can be eye dryness.
Reduced Tear Production
- Advancing age, usually in people over 60 years.
- After menopause (postmenopausal).
- Sjogren syndrome.
- Rheumatoid arthritis.
- Systemic lupus erythematosus (SLE).
- Thyroid disorders.
- Vitamin A deficiency.
- Laser eye surgery.
- Tear gland blockage or damage.
The eyelids also play an important role in preventing dry eyes. Firstly the eyelids spread the tears across the eye surface when blinking. Secondly the eyelids help to retain the moisture of the tears when it closes. Problems where the eyelids cannot close properly or completely may give rise to eye dryness.
- Entropion – eyelids turn inwards
- Ectropion – eyelids turn outwards
- Lagopthalmos – inability to close eyelids due to various causes like facial nerve palsy
- Blepharitis – eyelid inflammation
Reduced blinking can cause a similar problem and this is often seen with eyestrain. Concentrating for long periods of time at a fixed object, like staring at a television or computer screen, is one of the main causes of the problem. However, it can be averted with frequent blinking.
- Dry air
- Windy climate
- Air conditioned environments
- Cold rooms or walk-in fridges
- Exposure to chlorinated water (like in swimming pools)
A number of different drugs may contribute to eye dryness mainly by reducing tear secretion. These drugs include antihistamines, decongestants, antihypertensives, certain antidepressants, hormone replacement therapy (HRT) and certain drugs to treat acne like isoretinoin. Usually the eye dryness will resolve upon stopping the medication.
Signs and Symptoms
Dry eyes is a common symptom. It is associated with a host of other signs and symptoms:
- Eye redness
- Gritty sensation in the eyes
- Uncomfortable blinking
- Itchy eyes
- Visual disturbances (temporary)
Sometimes an episode of dry eyes is followed by watery eyes (excessive tearing) once the eyes are rested or the environment is changed. This excessive tearing is only temporary. People who experience chronic eye dryness are at risk of eye infections such as conjunctivitis and sometimes keratitis. Inflammation of the eyes associated with dryness can even lead to scarring of the cornea in severe cases. Dry eyes can sometimes also affect sleep as the eye movement during deep sleep can be uncomfortable.
Treatment of Dry Eyes
In most cases the once off episode of dry eyes is not a cause for concern and does not need to be treated. Simply blinking a few times and resting the eyes for a short period may be sufficient to restore normal eye moisture. However, repeated episodes or persistent dry eyes requires treatment. If it is due to underlying disorders or diseases then these conditions need to be treated and the eye dryness may resolve. Artificial tears can be administered in the form of eye drops and offer symptomatic relief.
- Antibiotics to treat infections of the eyelids or glands.
- Corticosteroids to treat inflammatory conditions that can lead to dry eyes.
- Hydroxypropyl cellulose inserts are slow-releasing artificial tears.
- Sealing tear ducts that drain the tears from the eyes.
- Unblocking oil glands that are blocked.
- Special contact lens that act as a shield to retain eye mositure.
Prevention of Eye Dryness
Environmental and lifestyle factors that cause eye dryness can often be easily prevented in most instances.
- Try to blink more regularly especially during long hours of starting at a television or computer screen. Stick a sign near the screen that will serve as a reminder to blink.
- Take regular eye breaks during prolonged eye work. A few seconds eye break every 20 minutes by closing the eyes or looking at various objects at varying distance is another helpful measure.
- Use artificial tear eye drops regularly if dry eyes is a problem. These eye drops not only helps to relieve dry eyes but if administered at regular intervals it can prevent eye dryness.
- Avoid fast moving air like sitting in line of an electric fan or even driving with the windows down. Air conditioning also causes eye dryness even if a person is not close to the air conditioning unit or vent.