PurposeTrachomatous trichiasis (TT) is usually described in terms of a cicatricial entropion of the upper lid; however, other forms of trichiasis have been reported. This variation in clinical phenotype is potentially important for treatment guidelines. Therefore, we investigated the range of disease type and severity encompassed by TT.MethodsIndividuals presenting with TT to surgical treatment campaigns were examined by a single ophthalmologist using the Detailed WHO Trachoma Grading System. Additional features were graded including: type of trichiatic lashes (metaplastic, misdirected, entropic), lower lid trichiasis, entropion severity and lid margin muco-cutaneous junction (MCJ) position.ResultsWe recruited 2556 individuals with previously un-operated TT in at least one eye (4310 eyes). The median number of lashes touching the eye was 2 (Range: 0 (epilating) - 133). Entropion was absent or mild in 2328 (54.0%) eyes, moderate in 1259 (29.2%) eyes and severe in 723 (16.8%) eyes. Trichiatic lashes were predominantly metaplastic or misdirected (80.2%) rather than secondary to entropion. 4204 (97.7%) had antero-placement of the MCJ. Lower lid trichiasis was present in 494 (11.5%). Entropion was more severe among those with a low BMI, female gender, age <50 years, moderate/severe conjunctival inflammation, central corneal opacity and severe conjunctival scarring.ConclusionsMany patients with TT have minimal or no entropion. The trichiasis is frequently attributable to metaplastic or misdirected eyelashes. The results of tarsal rotation surgery in TT patients without manifest entropion should be investigated and potentially alternative treatment strategies evaluated.