Reliability of photographs for grading trachoma in field studies

The validity and reliability of the use of photographs to assess active trachoma and scarring was studied in a village where the disease was hyperendemic. One hundred and thirty six subjects were graded clinically and had photographs taken of the upper tarsal plate. Agreement between the clinical grade in the field and the grade on the photograph was very good for follicular trachoma, severe trachoma, and scarring (kappa statistic values were 0.71, 0.74, and 0.73 respectively). In field studies photographic documentation of trachoma appears to be a valid and reliable approach.