Trachoma is a chronic follicular conjunctivitis cause by infection with Chlamydia trachomatis.
Slow spontaneous resolution of the infection is accompanied by scarring of the conjunctiva.
Many who live in endemic areas have repeated infections, causing significant palpebral conjunctival scarring and cicatricial entropion, leading to corneal ulceration and opacification.
According to current estimates there are still 84 million people in the world with active trachoma (chronic infection) in 55 countries in which the disease is still endemic (Solomon, New Engl J Med 2004).
In the 1970s it was estimated that 500 million people worldwide were affected by trachoma, of whom 7 million were blinded by the disease (Thylefors, Bull World Health Organ 1995).
As late as 1984, in Saudi Arabia, a national eye survey found that trachoma was still the second leading cause of blindness, after cataracts, with 9.5% of school children found to have clinical evidence of active trachoma (Tabbara, JAMA 1986; Sallam, Saudi Med J 2003).
Worldwide efforts have reduced the prevalence of trachoma dramatically, but it still accounts for about 3.6% of world blindness (Resnikoff, Bull World Health Organ 2004).
Several countries are close to being verified as having eliminated trachoma, including Morocco, Ghana, and Oman (Sommer, JAMA Ophthalmol 2014).
- As of 2014, there are still countries with high chlamydia prevalence, such as Ethiopia, South Sudan, and Nigeria, and countries where trachoma reduction programs have not yet gained significant traction such as Somalia and the Democratic Republic of Congo.
Efforts to eradicate trachoma can be understood from the example of rural Myanmar/Burma, where a Trachoma Control Program (TCP) was created in 1964, beginning with efforts to surgically correct trichiasis, followed by primary prevention programs using the World Health Organization (WHO) recommendations for antibiotics, facial hygiene and environmental change (Durkin, Ophthalmology 2007).
- The prevalence of active disease in this region in the 1960s was more than 30%.
- By 1975 the prevalence had been reduced to about 20%.
- In a 2005 survey of 2,076 inhabitants ≥ 40 years old in rural villages, the population percentage of trachomatous trichiasis and corneal opacity had been further reduced to 2.6%.
- SAFE is an acronym for surgery for trichiasis, antibiotic treatment, face washing and environmental improvements.
- WHO efforts include latrine construction, face-washing campaigns availability of clean water and widespread distribution of oral azithromycin.
- Eye-seeking flies are an important vector for the transmission of chlamydia and providing clean water and teaching children to clean the area around their eyes keeping it clear of secretions reduces spread of the disease.
- The British Broadcasting Corporation developed health education print material, radio programs and videos in support of the SAFE program (Edwards, Ophthalmology 2006).
- In 2 Ethiopian villages the polymerase chain reaction evidence of infection among children aged 1–5 years was reduced from 48% to 0% at 42 months through biannual mass distribution of azithromycin (Biebesheimer, Ophthalmology 2009).
- The mean elimination time is about 7–8 months faster if the antibiotics are distributed twice yearly, versus annual distribution (Gebre, Lancet 2012).
An arid climate is conducive to endemic infection, the prevalence is lower in regions with greater rainfall (Schwab, Ophthalmology 1995).
- Estimated at 1.3 million life years
- Economic burden estimated at $5.3 billion in lost productivity
Highest current incidence is in India, China, Africa, and the Middle East.
Low incidence in Europe and North America:
- Related to improved hygiene rather than trachoma elimination program
- Low-grade trachoma persists: In Roraima, Brazil, where trachoma was thought to have been eradicated, a recent survey of 6,986 students grades 1–4 showed the overall prevalence rate was still 4.5%.
- There are still municipalities in Roraima where the prevalence is particularly high among school children, around 10%, and the prevalence rate among 2,152 family and school contacts of those children 9.3% (Medina, Ophthalmology 2011).
Establish country of origin.
Inquire about travel or work in endemic areas.
- Clinical signs accumulate slowly over years.
- Often a latent period between infection and clinical signs
- Ocular irritation
- Reduced vision
- Conjunctival follicles
- Follicles often greater than 0.5 mm
- Conjunctiva/tarsal scarring (Arlt's line)
- Cicatricial entropion
- Dry eye
- Corneal opacification
- Central secondary to trichiasis/corneal drying
- Superior pannus
- Herbert's pits
- Depression resulting from resolved limbal follicles
Figure 1. Trachoma-related cicatricial entropion secondary to posterior lamellar scarring and contraction. Also note marked ocular surface disease with corneal scarring, indicative of chronicity. Image courtesy of Thomas M. Lietman, MD.
Figure 2. Inflamed palpebral conjunctiva in a patient with untreated active trachoma infection. Arlt's line refers to the linear scaring 2–3 mm adjacent the lash line. Incision along this line often aids in surgical repositioning of the eyelid margin. Also note disease-carrying flies on lower eyelid. Image courtesy of Thomas M. Lietman, MD.
Figure 3. Noninflamed scarred conjunctiva in a patient with treated tachoma infection. Note diffuse irregular scarring, indicative of years of untreated infection. Image courtesy of Thomas M. Lietman, MD.
Diagnosis can usually be inferred from clinical findings in appropriate setting.
Histopathology shows a thick, compact, subepithelial fibrous membrane adherent to the upper lid tarsus, loss of meibomian glands, loss of goblet cells, and degeneration of the tarsus with replacement by adipose tissue (al-Rajhi, Ophthalmology 1993).
In vivo confocal microscopy (IVCM) is a noninvasive means of obtaining high-resolution tissue images at a cellular level (Hu, Ophthalmology 2011).
- In normal conjunctiva, IVCM can identify normal epithelial cell nuclei, inflammatory cell nuclei, and dendritic cells.
- There are also tubular microcysts in the superficial conjunctiva which contain highly reflective material.
- There is a fine network of small blood vessels 20–30 microns beneath the surface and brightly reflective fibrous material.
- In trachomatous conjunctiva, with active disease, in children, IVCM demonstrates more numerous dendritic cells, with longer dendritic processes that are often interdigitating (Hu, Massae, Ophthalmology 2011).
- The cystic spaces are larger and more irregular.
- In trachomatous conjunctiva, with scarring, in adults, there is evidence of chronic inflammation, both papillary and follicular conjunctivitis, with an increase in inflammatory cells.
- Increased cysts and dendritic cells are seen in adults.
- With increasing severity of scarring, the deeper subepithelial connective tissue contains broad bands of scar tissue arranged in parallel.
In vivo confocal microscopy can be performed using the Heidelberg Retina Tomograph 3 (HRT3) in combination with the Rostock Cornea Module (RCM).
- This uses a 670‑nm diode laser as a light source with a special water-contact objective covered with a sterile single-use polymethylmethacrylate (PMMA) cap.
- A small amount of carbomer gel is used as a coupling agent.
- The device scans at a magnification of x800 and a lateral resolution of 1 micron.
Nuclear acid amplification tests (NAATs):
- Point of care assay of Chlamydial lipopolysccharides
Testing for staging, fundamental impairment
There is a simplified WHO trachoma grading system, mnemonic = FISTO:
- Trachomatous inflammation: follicular (TF) = the presence of 5 or more follicles in the upper tarsal conjunctiva.
- Trachomatous inflammation: intense (TI) = pronounced inflammatory thickening of the tarsal conjunctiva that obscures more than half of the deep normal vessels.
- Trachomatous scarring (TS) = presence of scarring in the tarsal conjunctiva.
- Trachomatous trichiasis (TT) = at least one lash rubbing on the eye.
- Corneal opacity (CO) = easily visible corneal opacity over the pupil.
- Exposure to endemic area
- Poor hygiene
- Ocular cicatricial pemphigoid
- Topical medication (glaucoma medication is most common)