Conceptual framework

Figure 1 conceptualizes where gender differences may arise as they relate to our TT management outcomes. At the time of the GTMP/TD cross-sectional survey, individuals’ eyes will be in one of the compartments shown in the figure. Eyes without TT may either have no history of TT or may have had successful surgery that resolved their TT; our data cannot distinguish between these two groups.

Conceptual framework describing categorization of study eyes regarding surgical management of trachomatous trichiasis*.

Among those with prevalent TT, an eye can appear in one of four compartments indicative of the surgical status of the eye (the letters, a-d, correspond to the response to the surgical management question provided in Box 1). Compartment ‘d’ (never been offered surgery) includes eyes newly diagnosed by GTMP/TD surveyors or eyes previously diagnosed (either through a previous GTMP/TD survey or other eye care services) but not offered surgery. Eyes in compartments ‘b’ (not yet had surgery) and ‘c’ (declined surgery) had been diagnosed and previously offered surgery by a health worker but had not received surgery in the time between diagnosis and the current examination. Finally, eyes in compartment ‘a’ (PTT) previously had surgery to correct TT but developed PTT. To reach this compartment, eyes exited the TT-prevalent population for some time and returned when PTT occurred.

The probabilities that dictate the transition of eyes through these compartments may differ by gender. If so, the compartment in which a surveyed eye appears will be a function of the gender-specific probability of incident TT, being diagnosed with TT, being offered (and accepting) surgery, having surgery, having incident PTT and being diagnosed with PTT. If the relative sizes of these compartments are unequal among men and women, this may inform the need for further investigations into any observed gender differences.