Classifying medial rectus muscle attachment in consecutive exotropia

Purpose To evaluate interexaminer agreement in classifying medial rectus muscle attachment in patients with consecutive exotropia. Methods A series of intraoperative photographs of 26 eyes in 25 patients who underwent surgery for consecutive exotropia were retrospectively studied. Two examiners independently classified the medial rectus attachment as either normal, stretched scar, slipped muscle, or lost muscle. Agreement between examiners was evaluated using the weighted kappa (κ) statistic, and causes of disagreement were assessed. Results Agreement was found in 15 of 26 eyes (58%), signifying "moderate" agreement (κ = 0.41). Approximately two-thirds of the disagreements, 7 of 11 eyes (64%), were between stretched scar and slipped muscle, with characteristics of each entity being present in the same muscle. Conclusions The clinical distinction between stretched scar and slipped muscle appears to be obscure. We propose that they should be considered a single entity, which could be referred to as "abnormal scleral attachment."