# Trachoma > Trachoma for FMGE Ophthalmology: Chlamydia trachomatis, WHO grading TF TI TS TT CO, the SAFE strategy, azithromycin dose and India elimination status. - Canonical URL: https://prepelephant.com/topics/fmge/ophthalmology/trachoma-fmge - Exam / course: FMGE · 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/fmge/ophthalmology/trachoma-fmge ## Direct answer Trachoma is chronic follicular conjunctivitis caused by repeated infection with Chlamydia trachomatis serotypes A, B, Ba and C, transmitted by flies and within families where faces are unwashed. Decades of repeated infection scar the upper tarsal conjunctiva, drawing the lashes inward (trichiasis) to abrade the cornea until it opacifies — the world's leading infectious cause of blindness. The WHO simplifies assessment into five signs, TF, TI, TS, TT and CO, and controls the disease with the SAFE strategy: Surgery for trichiasis, Antibiotics, Facial cleanliness and Environmental improvement. India has since been validated by WHO as having eliminated trachoma as a public health problem, though the grading and strategy remain examination favourites. ## What you must remember - TF (trachomatous inflammation — follicular): at least five follicles of 0.5 mm or more on the upper tarsal conjunctiva, indicating active infection needing antibiotics. - TI (trachomatous inflammation — intense): inflammatory thickening obscuring half or more of the deep tarsal vessels; the most contagious stage. - TS (trachomatous scarring): white linear or stellate tarsal scars, evidence of past infection. - TT (trachomatous trichiasis): at least one eyelash rubbing on the globe, an indication for lid surgery — bilamellar tarsal rotation — before the cornea ulcerates. - CO (corneal opacity): opacity over the pupil severe enough to blur vision, the blinding endpoint. - Antibiotic arm: a single oral dose of azithromycin 20 mg per kg (or topical tetracycline ointment twice daily for six weeks); treat the whole family or district as guided by prevalence. - Active disease (TF or TI) lives in children; the blinding sequelae (TS, TT, CO) appear in adults — the exam loves this age split. - F and E are the sustainable arm: face washing and fly control, safe water and latrines, without which antibiotics alone fail. ## Reading a tarsal conjunctiva, walked through Evert the upper lid of a village schoolchild with chronic watering and discharge. With the tarsal plate exposed under good light, apply the WHO sequence in order. First count follicles — pale, immature lymphoid elevations that look like sago grains; five or more across the upper tarsus grades the case TF, and this child needs azithromycin today, family treatment, and a lesson on face washing. Next assess vessel visibility: if boggy inflammatory thickening hides the deeper vessels over half the plate, the grade becomes TI as well — heavy infection, more infectious discharge, more urgent mass treatment of siblings. Now jump a few decades in your mind to the child's grandmother, whose lid you evert in the clinic. Her tarsus shows white cicatricial bands (TS) and, at the lid margin, several lashes turning in to strike a cornea already dull where they rub (TT with early CO). Her management is completely different: epilation gives brief relief, but definitive bilamellar tarsal rotation surgery redirects the lash line permanently, and corneal opacity may later need keratoplasty. One family, two patients, one disease at opposite ends of its natural history — that contrast is what examiners probe when they ask whether trachoma is treated with drops, tablets or scalpels. ## How the exam frames it Question-writers return to three discriminators. Which grades constitute active infection (TF, TI — treat with antibiotics) versus cicatricial sequelae (TS, TT, CO — treat surgically or rehabilitate). What the letters of SAFE stand for, with azithromycin dosing as the numerical hook. And the Indian programme angle: trachoma was a notified cause of blindness under surveys of the last century, the National Trachoma Survey of 2014-17 found prevalence far below elimination thresholds in children aged one to nine, and WHO has since validated India's elimination of trachoma as a public health problem — a fact now framed as a public-health success rather than a clinical workload. Candidates who can recite the five grades but cannot say which one is an indication for lid surgery lose the mark that matters. ## Frequently asked questions ### Which serotypes of Chlamydia trachomatis cause trachoma? Serotypes A, B, Ba and C; serotypes D through K cause genital chlamydial infection and inclusion conjunctivitis, including neonatal. ### What does TI signify on WHO grading? Intense trachomatous inflammation in which thickening obscures at least half of the deep normal tarsal vessels, indicating highly active, contagious infection. ### What is the antibiotic of choice in trachoma? A single supervised oral dose of azithromycin 20 mg per kg body weight; topical tetracycline ointment twice daily for six weeks is the alternative. ### Which trachoma grade requires lid surgery? TT, trachomatous trichiasis — at least one lash touching the globe — treated by bilamellar tarsal rotation to prevent corneal ulceration and opacity. ### What do the F and E of SAFE stand for? Facial cleanliness and Environmental improvement — face washing, fly control, safe water and sanitation, which prevent re-infection after antibiotic rounds.