Trachoma is an infectious eye disease that causes more preventable blindness than any other eye infection. It is rife in poor communities in developing countries, often affecting young children and their female carers.

What is trachoma?
Trachoma is due to a bacterial infection caused by Chlamydia trachomatis. It spreads when infected discharge from the eyes, nose or throat of one person is passed to another by touch. The bacteria can also be transferred on handkerchiefs or towels and by flies in tropical climates.

Trachoma infection causes inflammation of the eyelids which heals naturally after a month or two. Repeated infections, however, can lead to chronic inflammation and scarring of the inside of the eyelid. This eventually causes the eyelashes to turn inwards. The lashes then rub on the cornea, causing irreversible damage if untreated.

Who is affected by trachoma?
Improvements to sanitation and healthcare mean that trachoma, once common across much of the world, is now mainly restricted to more remote areas of developing countries. It is still common in parts of Africa, Asia, the Middle East, Australia, particularly in Aboriginal communities, and in Central and South America. A total of 55 countries still have regular cases, and around 84 million people are thought to be infected in 2011.

Symptoms of trachoma
The early symptoms of trachoma infection include eye irritation with pus or mucus discharge similar to conjunctivitis. After repeated infections, symptoms and signs can include:

  • Swollen eyelids
  • Turned-in eyelashes
  • Swollen lymph nodes in front of the ears
  • Light sensitivity
  • Blurred vision
  • Eye pain, often severe
  • A cloudy cornea
  • Vision loss.

World Health Organisation (WHO) trachoma grading system

The WHO has defined 5 trachoma grades to classify the symptoms of trachoma to indicate how severe the infection is:

  • Follicular trachoma (TF): 5 or more small inflamed lumps containing white blood cells can be seen on the inner surface of the upper eyelid. This form is most common in pre-school children.
  • Intense inflammatory trachoma (TI): someone at this stage has very inflamed and swollen upper eyelids and the conjunctival layer that lines their upper eyelids has already become thickened. At this stage, the infection is highly contagious and there is an increased risk of blindness.
  • Trachomatous scarring (TS): repeated infections have caused scarring of the upper eyelids and these often have obvious white lines. The risk of the eyelashes turning in is high.
  • Trichiasis (TT): at least one eyelash rubs on the eyeball, or there is evidence of turned-in eyelashes falling out. Someone at this stage has a high risk of blindness but it is not inevitable; some vision can be restored if the trichiasis is treated.
  • Corneal opacity (CO): the eyelashes rubbing on the cornea have caused it to become cloudy over the pupil. If not treated urgently, this person will lose their sight.