Table 1 The WHO simplified trachoma grading system¹¹⁵

Trachomatous trichiasis (TT)

At least one eyelash from the upper eyelid touches the eyeball, or evidence of recent epilation of in-turned eyelashes from the upper eyelid

Corneal opacity (CO)

Easily visible corneal opacity that is so dense that at least part of the pupil margin is blurred when viewed through the opacity

Trachomatous inflammation — follicular (TF)

The presence of five or more follicles, each at least 0.5 mm in diameter, in the central part of the upper tarsal conjunctiva

Trachomatous inflammation — intense (TI)

Pronounced inflammatory thickening of the upper tarsal conjunctiva that obscures more than half of the normal deep tarsal vessels

Trachomatous scarring (TS)

The presence of easily visible scarring in the upper tarsal conjunctiva