Figure 2.

Adult Strabismus Questionnaire 20 (AS-20) targeting for (A) self-perception subscale, (B) interaction subscale, (C) reading function subscale, and (D) general function subscale. The mean severity discrimination (difficulty) of the items was well matched to the mean severity (ability) of the strabismus for the self-perception subscale (mean 1.07 ± 3.90 logits for person vs. 0.00 ± 0.51 logits for items), but targeting for the interaction subscale was relatively poor (mean 2.66 ± 2.26 logits for person vs. 0.00 ± 0.54 logits for items). Items were well matched to the patient cohort for the reading function subscale (mean 0.62 ± 3.23 logits for person vs. 0.00 ± 0.76 logits for items) and the general function subscale (mean 0.45 ± 2.04 logits for person vs. 0.00 ± 0.34 logits for items). Despite a relatively narrow range of item difficulty for each subscale, a wide range of severity of the condition was evident. M, Mean; S, 1 standard deviation; T, 2 standard deviations.