# Trachoma

> Trachoma for MBBS Ophthalmology: Chlamydia trachomatis, WHO grading TF TI TS TT CO, SAFE strategy, azithromycin and complications for MBBS exams.

- Canonical URL: https://prepelephant.com/topics/mbbs/ophthalmology/trachoma
- Exam / course: MBBS · Subject: Ophthalmology
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Trachoma", PrepElephant, https://prepelephant.com/topics/mbbs/ophthalmology/trachoma

## Direct answer

Trachoma is a chronic keratoconjunctivitis caused by Chlamydia trachomatis serovars A, B, Ba and C, transmitted by eye-seeking flies and direct contact in settings with poor water and sanitation. Recurrent childhood infection causes conjunctival scarring that leads to trichiasis, corneal ulceration and opacity — historically a leading cause of preventable blindness in India. Control follows the WHO SAFE strategy: Surgery for trichiasis, Antibiotics, Facial cleanliness and Environmental improvement.

## What you must remember

- **Organism and transmission:** Chlamydia trachomatis is an obligate intracellular bacterium; the blinding serovars colonise the eye in crowded, dusty conditions with limited face washing, and repeated infection drives the scarring.
- **Active disease:** a follicular reaction in the upper tarsal conjunctiva with inflammatory thickening, mucopurulent discharge and, on slit lamp examination, limbal follicles with Herbert pits after regression; punctate keratitis and superior pannus are characteristic.
- **WHO grading:** TF — five or more follicles of at least 0.5 mm in the central upper tarsal conjunctiva; TI — intense inflammation obscuring half or more of the deep tarsal vessels; TS — trachomatous scarring, the white Arlt line; TT — trachomatous trichiasis with at least one lash rubbing the globe; CO — corneal opacity obscuring part of the pupil margin.
- **Complications:** cicatricial entropion and trichiasis, corneal ulceration and vascularisation, corneal opacity, destruction of goblet cells and lacrimal ductules producing dry eye, and dacryocystitis from lacrimal scarring.
- **Diagnosis:** clinical grading by the WHO system in the field; laboratory support from Giemsa staining showing basophilic intracytoplasmic inclusions (Halberstaedter-Prowazek bodies), antigen detection or PCR where needed.
- **Treatment:** a single oral dose of azithromycin (about 20 mg per kg) is the standard mass-treatment drug; alternatives are topical tetracycline ointment twice daily for six weeks; the whole family or community is treated together.
- **Trichiasis management:** epilation as a stopgap, but definitive lid surgery — tarsal fracture with rotation or bilamellar tarsal rotation — prevents progression to corneal blindness.

## Common confusion

Trachoma is often confused with inclusion conjunctivitis of the adult, caused by the genital serovars D to K: that disease is acute, follicular and self-limiting without scarring, whereas trachoma is chronic, community-associated and blinding. Students also mix up TT with simple trichiasis from other causes — in TT the lid changes of TS accompany the in-turned lashes. Note that modern surveys show active trachoma has become uncommon in most of India, remaining only in pockets, so a diagnosis of trachoma today should be supported by the full WHO grade and epidemiology rather than assumed from follicles alone.

## Exam-focused takeaway

In theory, prepare trachoma as a full-length answer: cause, transmission, WHO grading, complications and SAFE strategy, since it bridges clinical ophthalmology and community medicine. In viva, expect the grading letters to be expanded exactly, the drug and dose for mass treatment, and why surgery precedes antibiotics alphabetically in importance for the blind. In the posting, evert every lid with chronic conjunctival scarring, look for Arlt lines, Herbert pits and trichiasis, and refer lid surgery early — the cornea of a trachoma patient waits for no one.

## Frequently asked questions

### Which organism causes trachoma and which serovars?

Chlamydia trachomatis; the blinding serovars are A, B, Ba and C, while serovars D to K cause inclusion conjunctivitis and genital infection.

### What does the SAFE strategy stand for?

Surgery for trichiasis, Antibiotics for active infection, Facial cleanliness and Environmental improvement — the WHO package for trachoma elimination.

### What is the meaning of the WHO grade TI?

Trachomatous inflammation intense — inflammatory thickening of the upper tarsal conjunctiva obscuring fifty per cent or more of the deep normal vessels.

### What are Arlt line and Herbert pits?

An Arlt line is a linear band of conjunctival scarring in the upper tarsus; Herbert pits are depressed limbal scars left after limbal follicles heal, both cicatricial signs of trachoma.

### How is active trachoma treated?

A single weight-based oral dose of azithromycin, or topical tetracycline ointment twice daily for six weeks when azithromycin cannot be used, with simultaneous treatment of contacts.

### Why does trachoma cause blindness?

Recurrent inflammation scars the tarsal conjunctiva, producing entropion and trichiasis; the abrading lashes ulcerate and opacify the cornea, and dry eye from gland destruction worsens the damage.