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Dry eye syndrome

Dry Eye is a common condition where your eyes do not produce enough tears (Aqueous-deficient), or where the tears evaporate too quickly (Evaporative). It can leave your eyes feeling dry, irritated and sore. In some instances it may cause blurred vision.

What causes it?

The tear film

The front surface of the eye is covered by a thin layer of liquid called the tear film; this helps to keep your eyes moist. It provides a smooth surface for light to pass through to the eye, while nourishing and protecting your eye against infection.

The tear film is made up of three layers: the oily layer (lipid), the watery layer (aqueous) and the mucous layer. Dry eye syndrome is when you don’t have enough of one of these layers.

Common causes of dry eye

There are a number of factors that can cause dry eye; listed below are a few of the most common causes: Runner sunset

  • Environment. Sun, wind, dry climate, hot blowing air and high altitude can have a drying effect on your eyes. Your tears will evaporate quicker than they can be produced and leave you with dry eye.
  • Activities. Using a computer, reading, and writing can also cause dry eye. People tend to blink less while carrying out these activities; leaving the tear film free to evaporate.
  • Ageing. The eye naturally produces fewer tears as you get older. The eyelids become less effective at spreading the tear film evenly across the eye; leaving dry patches that can cause irritation.
  • Contact lenses. Some contact lens materials can dehydrate on the eye quicker than others, causing dry eye symptoms. Wearing your lenses for longer than recommended can also cause your eyes to become dry and irritated.
  • Meibomian gland dysfunction (MGD). The meibomian gland releases the oily part of your tear film. These glands can become blocked, and over time can stop the oily lipid layer from escaping, causing evaporative dry eye. This normally occurs as a result of skin disorders, or hormone levels.
  • Medical conditions. There are a number of medical conditions can affect the production of tears, below you find a list of the most common:
    • Sjögren's Syndrome. a condition that can cause excessive dryness of the eyes, mouth and other organs.
    • Rheumatoid Arthritis. a condition that causes pain, swelling and inflammation in the joints, including the glands around the eyes.
    • Pregnancy. Changes in hormone levels can affect the production of tears.
  • Medications or  Laser Eye Surgery. Dry eye can also occur after certain medications or laser eye surgery.

What are the symptoms of dry eye?

Dry eye symptoms are mild and can be easily treated for most people. More severe and longstanding cases can be painful and lead to complications. Symptoms often include:

  • Feelings of dryness, grittiness or soreness
  • A feeling of sand/object in the eye
  • Itchiness
  • Red eyes
  • Eyelids that stick together when you wake up

You may even notice watery eyes; this happens when the eye tries to compensate for a lack of tears by producing more of the watery layer to relieve the irritation. This will relieve the symptoms for a short period, but can become more of a nuisance.

Severe symptoms of dry eye include:

  • Sensitivity to light (photophobia)
  • Extremely red and painful eyes
  • Blurred vision

Severe symptoms can be a sign of a serious complication, such as scarring of your cornea. If you notice any of the above symptoms arrange an appointment with your Optician who will be able to provide the best treatment options.

Close up of the contact lens wearer's eyes

How are dry eyes diagnosed?

In most cases your optician can diagnose dry eyes from a simple discussion about the symptoms. However, because dry eyes can be a symptom of an underlying disease, they may ask a range of questions to eliminate these.

A yellow-orange dye (fluorescein) is used so your optician can see your tears more clearly. This helps them find out how long it takes for your eye to start drying out and whether this is within normal limits. If there is damage to the surface of the eye, the fluorescein dye test may also highlight the affected areas.

Your Optician will also assess your meibomian glands and tear ducts to find all probable causes of dry eye.


The most popular treatment for dry eye is dry eye drops. If caused by contact lens wear, it is worth speaking to your Optician about your prescription, and/or changing the amount of time spent wearing lenses.

For more information on how to reduce and treat dry eye, read our article on dry eye treatment.