Expanding a photographic grading system for trachomatous scarring

Background: The purpose was to assess an expansion of a previously published photographic four-step severity grading scale for trachomatous scarring (TS). Methods: Images of everted eyelids of adult women in Tanzania were graded for the presence and severity of TS. The previous S3 grade was subdivided into two categories: S3A, one-third to <50% of the upper eyelid conjunctiva scarred; and S3B, 50% to <90%. The reliability and ease of use were evaluated. This new categorisation was then applied to images taken of the same women 5 y prior to evaluate whether it could help detect previously undetected progression. Results: In total, 142 eyes at baseline and 418 eyes at follow-up after 5 y were graded as S3. Interobserver agreement using the expanded scarring grading scale was a kappa of 0.86. At baseline, 51 (35.9%) eyes were S3A and 91 (64.1%) were S3B. At follow-up after 5 y, 36.6% of the eyes that were previously documented as not having progressed were now detected as having progressed from S3A to S3B. S3B images were more likely to progress to S4 compared with S3A (OR 4.6, 95% CI 2.1 to 9.9). Conclusions: Adding S3A and S3B is reliable and detects more scarring progression. It will be beneficial for future studies analysing TS in photographs.