The simplified trachoma grading system, amended.

Anthony W Solomon,Mathieu Bangert,Hugh R Taylor,Sheila K West,Allen Foster,Amir B Kello,Rabebe Tekeraoi

doi:10.2471/blt.19.248708

Abstract

A simplified grading system for trachoma was published by the World Health Organization (WHO) in 1987. Intended for use by non-specialist personnel working at community level, the system includes five signs, each of which can be present or absent in any eye: (i) trachomatous trichiasis; (ii) corneal opacity; (iii) trachomatous inflammation—follicular; (iv) trachomatous inflammation—intense; and (v) trachomatous scarring. Though neither perfectly sensitive nor perfectly specific for trachoma, these signs have been essential tools for identifying populations that need interventions to eliminate trachoma as a public health problem. In 2018, at WHO’s 4th global scientific meeting on trachoma, the definition of one of the signs, trachomatous trichiasis, was amended to exclude trichiasis that affects only the lower eyelid. This paper presents the amended system, updates its presentation, offers notes on its use and identifies areas of ongoing debate.

Highlights

Trachoma is the most important infectious cause of blindness.[1]
The amendment to the definition of trachomatous trichiasis introduced in this version of the World Health Organization (WHO) simplified trachoma grading system has been endorsed by WHO
Excluding lower-eyelid-only disease will avoid trichiasis caused by involutional entropion being misinterpreted as trachomatous trichiasis

Summary

Introduction

Trachoma is the most important infectious cause of blindness.[1]. Repeated conjunctival infection[2] with particular strains of Chlamydia trachomatis[3,4,5] results, in some people, in conjunctival scarring, trichiasis and corneal opacity. Trachoma may be hyperendemic, severe and blinding; or less severe and non-blinding.[8] Models suggest that more than 150 episodes of C. trachomatis infection are required to develop trichiasis from trachoma;[9] immune responses to infection are critical in the pathogenetic pathway.[10,11] Populations presumably transition from having blinding to non-blinding disease through reductions in intensity of ocular C. trachomatis transmission. This paper draws heavily from the original article.[19]

Method of examination

Findings

Discussion