Trachoma grading by WHO simplified system (TF, TI, TS, TT, CO) — which grade is the direct indication for surgical intervention?
- A TT (trachomatous trichiasis) — at least one eyelash touching the globe ✓
- B TF (trachomatous follicles) — 5 or more follicles in the upper tarsal conjunctiva
- C TI (trachomatous intense inflammation) — diffuse papillary hypertrophy obscuring >50% of normal deep tarsal vessels
- D TS (trachomatous scarring) — white fibrous lines in tarsal conjunctiva
Correct answer: A. TT (trachomatous trichiasis) — at least one eyelash touching the globe
Explanation
The WHO simplified trachoma grading system identifies TT (trachomatous trichiasis) as the grade requiring surgical intervention. TT is defined as at least one eyelash touching the globe or evidence of recent epilation. The lashes cause corneal abrasion leading to CO (corneal opacity). Surgery (bilamellar tarsal rotation — BLTR) redirects lashes away from the corneal surface and is the only effective intervention to prevent corneal scarring. TF and TI are active inflammatory stages treated with azithromycin (SAFE strategy); TS indicates prior scarring.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.