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TRACHOMA – Mode of Infection, Clinical Manifestations, Classification, Diagnostic Evaluation and Medical Management

TRACHOMA – Mode of Infection, Clinical Manifestations, Classification, Diagnostic Evaluation and Medical Management

Trachoma (Ancient Greek: “rough eye”) is an infectious eye disease and the leading cause of the world’s infectious blindness. Alternative names are Granular conjuncitivis; Egyptian ophthalmia; Conjunctivitis granular. This disease is a chronic keratoconjunctivitis caused by the bacterium Chlamydia trachomatis. The bacterium has an incubation period of 5 to 12 days, after which the affected individual experiences symptoms of conjunctivitis, or irritation similar to “pink eye”. Globally, 84 million people suffer from active infection and nearly 8 million people are visually impaired as a result of this disease. Globally this disease results in considerable disability.

MODE OF INFECTION

Young children bear the heaviest burden of trachoma infections and are the main source of infection for other people. It is spread by direct contact with eye, nose, and throat secretions from affected individuals or contact with fomites.

Transmission takes place when the bacteria move from the eyes of young children to the eyes of an uninfected person through several different ways: flies, touching eyes, mother’s shawls, bed sheets, pillows and towels.

Infection spreads from person to person, and is frequently passed from child to child and from child to mother, especially where there are shortages of water, numerous flies, and crowded living conditions.

 

CLINICAL MANIFESTATIONS

Symptoms begin 5 to 12 days after being exposed to the bacteria. The condition begins slowly as inflammation of the tissue lining the eyelids (conjunctivitis, or “pink eye”), which if untreated may lead to scarring.

The principal signs and symptoms of trachoma include:

  • Cloudy cornea
  • Discharge from the eye
  • Swelling of lymph nodes just in front of the ears
  • Swollen eyelids
  • Turned-in eyelashes
  • Mild itching and irritation of the eye
  • Discharge from the eye containing mucus or pus
  • Marked light sensitivity (photophobia)
  • Blurred vision and eye pain


 

McCallan Classification of Trachoma

MacCallan has divided trachoma into four stages.

Stage I
– Marked congestion or hyperemia of the palpebral conjunctiva with formation of papillae and immature follicles
Stage II – This stage is characterized by the presence of mature follicles and trachomatous pannus
Stage III – This stage is characterized by the conjunctival scarring and Herbert’s pits. Herbert’s pits are follicle-like infiltrations near the limbus
Stage IV – It is the stage of sequelae or complications. The complications are entropion of upper eyelid, trichiasis, chalazion formation, and corneal opacity.

 

WHO Classsification


The World Health Organization recommends a simplified grading system for trachoma. The simplified WHO Grading System is summarized below:

  1. Trachomatous Inflammation Follicular (TF) – Follicular trachoma is defined as the presence of 5 or more follicles at least 0.5 mm in diameter in the central part of the upper tarsal conjunctiva.
  2. Trachomatous Inflammation Intense (TI) – Papillary hypertrophy and inflammatory thickening of the upper tarsal conjunctiva obscuring more than half the deep tarsal vessels.
  3. Trachomatous Scarring (TS) – Trachomatous scarring is defined as the presence of easily visible scars in the tarsal conjunctiva. This form may be associated with the development of dry eye syndrome, but chronic, low-grade bacterial conjunctivitis and dacryocystitis may also lead to a weeping eye.
  4. Trachomatous Trichiasis (TT) – Trichiasis is defined as at least 1 eyelash rubs on the eyeball or evidence of recent removal of in-turned eyelashes. This is a potentially blinding lesion that can lead to corneal opacification. Trichiasis is due to subconjunctival fibrosis over the tarsal plate that leads to lid distortion.
  5. Corneal Opacity (CO) – Easily visible corneal opacity present over the pupil and causing less than 6/18 vision. This condition includes pannus, epithelial vascularization and infiltration only if it involves the central cornea.


 

DIAGNOSTIC EVALUATIONS

An eye exam may reveal scarring on the inside of the upper eye lid, redness of the white part of the eyes, and new blood vessel growth into the cornea. Laboratory tests are needed to accurately identify and detect the bacteria and diagnose trachoma.

 

MEDICAL MANAGEMENT


The key to the treatment of trachoma is the SAFE strategy developed by the WHO. The SAFE strategy is Surgery (to correct eyelid defects that lead to blindness), Antibiotic therapy (to eradicate active chlamydial infection), Facial cleanliness and Environmental improvement (particularly the provision of clean water supplies).

  1. Surgery: Eyelid surgery to correct trichiasis is important in people with trichiasis, who are at high-risk for trachomatous visual impairment and blindness. Eyelid surgery to correct entropian and/or trichiasis may prevent blindness in individuals at immediate risk. Eyelid rotation limits the progression of corneal scarring. In some cases, it can result in a slight improvement in visual acuity, probably due to restoration of the visual surface and reductions in ocular secretions and blepharospasm.
  2. Antibiotic therapy: The WHO recommends 2 antibiotics for trachoma control: oral azithromycin and tetracycline eye ointment. The antibiotic of choice for treating active trachoma is azithromycin. The dose for children is 20 mg/kg in a single dose; adults receive a single dose of 1 gm. The second-line treatment is topical tetracycline eye ointment 1%. Topical tetracycline is applied to both eyes twice a day for 6 weeks.
  3. Facial cleanliness: Epidemiologic studies and community-randomized trials have shown that facial cleanliness in children reduces both the risk and the severity of active trachoma. To be successful, health education and promotion activities must be community based and require considerable effort.
  4. Environmental change: Environmental change activities are the promotion of improved water supplies and improved household sanitation, particularly methods for safe disposal of human feces. These activities should be prioritized. The flies that transmit trachoma preferentially lay their eggs on human feces lying exposed on the soil. Controlling fly populations by spraying insecticide is difficult. Studies on the impact of fly control on trachoma have had variable results. Trials undertaken to evaluate the installation of pit latrines suggested that the prevalence of trachoma was reduced but failed to demonstrate a statistically significant effect.

TRACHOMA – Mode of Infection, Clinical Manifestations, Classification, Diagnostic Evaluation and Medical Management