Giant papillae versus lymphoid follicles of the conjunctiva

Trachoma is a cause of blindness that has long been neglected. We were therefore delighted to see material on the diagnosis of trachoma in a recent issue of Annals of Emergency Medicine.¹ However, we think the case that prompted the submission of this paper is more likely to be allergic rather than infectious in origin, for two reasons. First, the reported tearing and itch that are prominent in the history would be atypical for trachoma,² but are classic features of an allergic conjunctivitis. Second, the papillary hypertrophy noted by the authors in their description and clearly displayed on their excellent photograph is caused by giant papillae rather than the lymphoid follicles of trachoma. These two entities may provoke diagnostic uncertainty; both can cause conjunctival elevation, but giant papillae are relatively translucent, > 1mm in diameter, and tend to be quite protuberant above the plane of the conjunctival surface, while follicles are grey-white, creamy or yellow-coloured, can be as small as 0.5mm in diameter and still be considered significant,³ and lie deep to conjunctival epithelial cells: the surface of the epithelium can be elevated as a consequence of their presence, but not to the extent of the cobblestoning sometimes seen with giant papillae. For the purposes of standardizing population-based surveys to estimate the prevalence of trachoma, intensive training courses are conducted for ophthalmic health workers.^{4, 5} For emergency room work, however, reference to the grading card of the WHO simplified system³ may be helpful.