Active trachoma: Follicles and their sequelae

(A) World Health Organization (WHO) grade TF (trachomatous inflammation, follicular). To make a diagnosis of WHO grade TF, five or more white or yellow follicles >0.5 mm must be visualized on the upper tarsal conjunctiva.
(B) Herbert's pits. Herbert's pits are shallow pits in the cornea that form as a result of follicle rupture. They are pathognomonic for trachoma but are not assessed in the current grading scheme.