Date Published:2016 Jan 1
IMPORTANCE: Understanding the criteria for when strabismus becomes detectable by non-health care professionals could influence the goals for determining the success of surgical intervention and how patients with such misalignments are counseled. OBJECTIVE: To examine the magnitude at which strabismus is detectable by lay observers in an ethnically diverse set of images. DESIGN, SETTING, AND PARTICIPANTS: Photographs of 12 ethnically diverse models (black, white, and Asian) were simulated to have strabismus from esotropia of 21 prism diopters (∆) to exotropia of 21∆. From July 1, 2007, to October, 1, 2008, images were presented to 120 non-health care professionals aged 21 years or older from the general community in Boston, Massachusetts, who were asked whether strabismus was present. Analysis was conducted from November 1, 2008, to March 31, 2009. MAIN OUTCOMES AND MEASURES: The threshold angle for detecting strabismus to enable 70% of lay observers to make a positive determination whether strabismus is present. RESULTS: In white and black models, the threshold allowing a 70% positive detection rate was higher for esotropia than for exotropia (P < .001 for both). For white models, the threshold was 23.2∆ (95% CI, 21.0∆ to 26.5∆) for esotropia and 13.5∆ (95% CI, 12.5∆ to 14.6∆) for exotropia. For black models, the threshold was 20.8∆ (95% CI, 19.2∆ to 22.2∆) for esotropia and 16.3∆ (95% CI, 15.5∆ to 17.2∆) for exotropia. Asian models showed an opposite trend, with the threshold allowing a 70% positive detection rate for esotropia (14.3∆; 95% CI, 13.2∆ to 15.7∆) being lower than that for exotropia (20.9∆; 95% CI, 18.0∆ to 24.6∆) (P < .001). CONCLUSIONS AND RELEVANCE: Esotropia was easier for lay observers to detect than exotropia in Asian models, and exotropia was easier to detect than esotropia in white and black models. This information should be considered when managing patients who have concerns about the social significance of their strabismus. Future studies should include diverse individuals and make an effort to account for individual factors that may alter the perception of strabismus.