Impact of facial anthropometric features on exotropia perception

To evaluate whether subtle facial anthropometric variations may influence the perceived noticeability of exotropia.

This was a cross-sectional study of adult participants over the age of 18 years old recruited via social media platforms. Digitally generated facial images were used to create a baseline male face with a constant moderate-angle left exotropia and eight modified images with ±5% changes in palpebral fissure length, intercanthal distance, facial width, and facial height. Participants completed randomized pairwise comparisons, selecting which image demonstrated more noticeable ocular misalignment. Relative noticeability was quantified using Elo rating scores. A Bradley-Terry model was used to estimate odds ratios comparing each modified image with baseline. Subgroup analyses were performed by sex and age. The main outcome measure was perceived noticeability of exotropia based on participant-selected pairwise comparisons.

A total of 201 participants completed the survey (mean age 32.5 ± 11.4 years; 59.2% female). Both decreased palpebral fissure length (Elo score: 1 517.27 ± 16.6) and decreased intercanthal distance (Elo score: 1 512.72 ± 14.1) were ranked as having higher perceived noticeability of exotropia, whereas increased palpebral fissure length (Elo score: 1 485.58 ± 16.4) was ranked as having a lower perceived noticeability. In the Bradley-Terry model, decreased palpebral fissure length (OR 5.87, p < .001), decreased intercanthal distance (OR 3.96, p < .001), and increased intercanthal distance (OR 1.43, p < .05) were associated with higher odds of perceived noticeability relative to baseline, while increased palpebral fissure length (OR 0.41, p < .001) was associated with lower odds. Modifications in facial width and facial height were not statistically significant compared to baseline. Perceived noticeability did not differ by participant sex or age group.

Subtle variation in periocular facial anthropometric features may influence the perceived noticeability of exotropia independent of deviation magnitude. Periocular features, particularly palpebral fissure length and intercanthal distance, appear to play a greater role in perception than broader facial dimensions. These findings suggest that facial context may contribute to the cosmetic appearance of strabismus and may help explain variability in perception among patients with similar measured deviations.