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Dry Eye Syndrome

What is dry eye syndrome?

Dry eye syndrome, also referred to as keratoconjunctivitis sicca (KCS), occurs when the eyes either do not produce enough tears or more commonly when the quality of the tears they produce is insufficient. In each case, this causes the ocular surface to dry out and as a result the eyes can become red, swollen and irritated.

Who suffers from dry eye syndrome?

Although it can happen at any age, dry eye syndrome tends to become more common as we get older and especially over the age of 60 years. It also tends to be more common in females than in males.

How do you classify dry eye syndrome?

Dry eye syndrome can be sub-divided into two broad categories based on the mechanism by which the eyes dry out. These are:

  • Aqueous Layer Deficiency Dry Eye

This is the less common of the two types and occurs when the eyes do not produce enough tears. There can be many reasons for why this would happen, examples including age, vitamin A deficiency, certain medications (e.g. oral contraceptives, antidepressants), rheumatoid arthritis or Sjögren syndrome (i.e. an autoimmune condition characterised by reduced secretion of glands and mucous membranes throughout the body).

  • Evaporative Dry Eye

This is the more common of the two types and occurs when the eyes do produce enough tears but unfortunately the tears they produce are of a poor quality. The unstable nature of the tear film that results causes it to evaporate or dry out, leading to ocular surface disease. There are many causes of this type of dry eye, examples including:

  • Contact lens wear
  • Ineffective blinking
  • Increased exposure of the ocular surface
  • Meibomian Gland Dysfunction (MGD)


Although it is easy for us to classify dry eye syndrome in terms of these two broad categories, it is important to recognise that there can be overlap between them and that they do not necessarily occur in isolation of each other.

What are the symptoms of dry eye syndrome?

There are people who may have signs of dry eye syndrome when examined but who may not suffer from any of the symptoms associated with it. However, for those who do experience symptoms they could report any and/or all of the following:

  • Burning sensation in the eyes
  • Gritty sensation in the eyes
  • Irritation/Itchiness of the eyelids and/or eyes
  • Pain/Discomfort on looking at lights (i.e. photophobia)
  • Stringy discharge from the eyes
  • Increased watering of the eyes
  • Intermittent blurring of vision (i.e. having to blink to clear the vision)


Those who do experience the symptoms associated with dry eye syndrome will know that these symptoms tend to worsen as the day goes on.

Why do my eyes water if they are dry?

When we blink, the eyelids mechanically spread the tear film over the ocular surface (essentially doing the opposite to what the windscreen wipers on a vehicle would do). However, when there is not enough of this tear film being produced or conversely when the tear film is drying out too quickly, the ocular surface dries out and becomes inflamed. When receptors on the ocular surface become stimulated by this inflammation and/or environmental factors (e.g. windy weather), the response of the eye is to produce more tears in order to compensate for the dry ocular surface. The receptors trigger the glands responsible for tear production to literally ‘turn the tap on’, hence why our eyes water.

Can dry eye syndrome affect my vision?

Dry eye syndrome does not generally cause any visual deterioration. However, when the quantity and/or quality of the tear film are compromised it can cause temporary blurring of the person’s vision and they may find themselves having to blink to clear their vision as a result. It is also important to note that in severe cases of dry eye syndrome (i.e. when the eye is left to desiccate) there is a possibility that the cornea, the transparent front surface or ‘window’ of the eye, may scar and this could then lead to reduced vision on a potentially more permanent basis.

How do you check for signs of dry eye syndrome?

The best way for us to check for signs of dry eye syndrome is to look at your eyes through a slit lamp bio microscope. This piece of equipment allows us to view your eyes under magnification and better assess the quantity and quality of your tear film.

Another useful approach is to instil Fluorescein into the eye. This is a dye that temporarily colours your tears and fluoresces when viewed with a cobalt blue filter. When the cornea becomes damaged in dry eye syndrome, its outer layer loses cells. Although these cells regenerate within 24 hours, the ‘dyed’ tears collect in the divots they leave behind and allow us to gauge the extent of any ocular surface disease that may be present.

How is dry eye syndrome treated?

Unfortunately there is no cure for dry eye syndrome and so any treatment is with a view to managing and providing relief from the symptoms associated with it. There are various ways in which this can be achieved and, depending on its severity, this management of the dry eye syndrome could include any and/or all of the following approaches:

  • Eyelid margin hygiene

This would apply if the underlying cause of the dry eye syndrome was related to blepharitis. For more information specifically on this condition and how to manage it, please refer to the ‘Blepharitis’ section.

  • Tear substitutes

Regular use of eye drops, gels and/or ointments can help to lubricate the ocular surface and counteract the effects of dry eye syndrome. It is also not uncommon for them to be used in conjunction with the management of eyelid margin hygiene. There are a wide range of products out there so if you are unsure as to what would be best to use, please ask either us, your GP or an ophthalmologist (if applicable) for advice.

  • Punctal plugs

The puncta are the small openings located on our eyelid margins through which our tears drain away. We have a punctum on our upper eyelid and a punctum on our lower eyelid, both of which being situated towards our nose. In severe cases of dry eye syndrome, there is the option of blocking these puncta in order to prevent the tears from being drained away. This helps to sustain the lubrication provided by our tears (and tear substitutes) at the ocular surface. Temporary plugs are normally inserted to begin with and in some cases permanent plugs with cautery may be used.

Other options to consider in addition to those listed above include:

  • Staying hydrated throughout the day
  • Remembering to blink when looking at a screen or doing a concentrated task
  • Taking regular breaks from screens and concentrated tasks
  • 20-20-20 rule (i.e. for every 20 minutes of looking at a screen or doing a concentrated task, take 20 seconds to look at something about 20 feet away from you)
  • Avoiding air-conditioned environments
  • Avoiding central heating
  • Avoiding sources of direct heat (e.g. open fires)
  • Using a room humidifier (as moist air leads to less evaporation of tears)


If you believe you may be experiencing some degree of dry eye syndrome then please do not hesitate to contact us for advice.

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