Dry eye syndrome, also called keratoconjunctivitis sicca, is a common condition that develops when the eyes do not produce enough tears, or when tears that are produced dry up too quickly. Dry eye syndrome causes discomfort and can result in the eye becoming inflamed.

Dry eye syndrome is very common, with some studies suggesting that up to 3 out of 10 people have problems with dry eyes at some point during their life. Although it can occur at any age, dry eye syndrome tends to mainly affect people over 50, with women more susceptible than men.

What symptoms does dry eye syndrome cause?
The production of tears is regulated by the lacrimal functional unit. This consists of the lacrimal gland, the eyelid, the cornea, the meibomian gland and the lacrimal duct (the tear duct). If any part of this is affected, the whole system can break down. This can impact both the quantity and quality of tears produced, resulting in dry eye syndrome.

Some common symptoms of dry eye syndrome include:

  • A sandy or gritty feeling as if there is something in the eye.
  • Itchy eyes that you feel you need to scratch or rub.
  • Red eyes.
  • Eyes that sting, or feel as though they are burning.
  • Painful eyes.
  • Eyes that water; watery eyes can be worse outside.
  • Eyelids stick together and crusty eyelashes first thing in the morning.
  • Tired eyes with heavy eyelids.
  • Not being able to cry with tears when you are upset.

Although not normally serious, severe dry eye syndrome that is left untreated has the potential to cause complications such as loss of vision, corneal scarring and conjunctivitis. Symptoms of more serious dry eye syndrome include extreme sensitivity to light, red eyes, very painful eyes and blurred vision.

Main causes of dry eye syndrome
The main underlying causes of dry eye syndrome are:

  • Environmental factors: the sun, wind, warm air conditioning, dry climate and high altitude can all have a drying effect on eyes, causing tears to evaporate.
  • Occupation: activities that need a high level of sustained visual concentration, such as reading, writing, sewing, watching TV or computer work, reduce blinking, which can cause tears to evaporate.
  • Hormones: some hormones help to stimulate tear production and the changes in hormone levels during the menopause may explain why older women are more affected by dry eye syndrome than men. Pregnant women or those taking HRT are also prone to develop dry eye symptoms.
  • Nervous system: tearing can be triggered as a means of protecting our eyes from potential damage, like exposure to a smoky environment.
  • Medicines: dry eye syndrome can occur as a side effect of antihistamines, antidepressants, beta-blockers, diuretics, nasal decongestants, birth control pills and some blood pressure medicines.
  • Blepharitis: many people with dry eye syndrome also develop blepharitis, a condition in which the rims of the eyelids become inflamed.
  • Medical conditions: dry eye syndrome occurs with conjunctivitis, contact eczema, diabetes, polycystic ovary syndrome, thyroid disease, rheumatoid arthritis and immune system disorders like Sjögren's syndrome and lupus.
  • Contact lenses: some types of contact lenses can irritate the eyes and cause dry eye syndrome.
  • Age: tear production reduces as we get older, so dry eyes are often linked to ageing.
  • Lifestyle: smoking and an unhealthy diet can also have an adverse affect on dry eyes.