Non-Surgical Consecutive Exotropia following Childhood Esotropia: A Multicentered Study

Purpose: Non-surgical consecutive exotropia (NCX) occurs when an esotropia (ET) spontaneously converts to exotropia (XT) without surgical intervention. Although considered to occur in early onset accommodative esotropia with high hyperopia, consensus on causation is lacking. We report the clinical characteristics of NCX and assess response to conservative management. Design: Retrospective, multi-centered observational case series. Methods: Patients aged 6 months and older with initial diagnosis of esotropia who converted to exotropia without surgical intervention. Sensory strabismus was excluded. Age, visual acuity, cycloplegic refraction, glasses prescriptions, deviation and binocular vision were collected. Results: Forty-nine children were included with a mean age of 3.5±1.6 and 8.4±3.6 years at time of ET and NCX, respectively. Mean refractive error was +4.40±2.13D and +4.05±2.74D at time of ET and NCX, respectively. Accommodative esotropia occurred in 60% of cases, and only 35.7% were high hyperopes. All but one patient presented with their XT at distance. In response to the XT, a mean decrease in hyperopic prescription of 1.55±0.48D was given (N=17); only 1 case reverted to esotropia. Eventually, 43% had exotropia surgery, with similar rates between those who had refractive management and those who did not. Conclusions: NCX occurs in both accommodative and non-accommodative esotropia; high hyperopia is present in only a third of cases. On average, drift to exotropia occurs within 5 years. Refractive management has a modest result. No predictive risk factors were identified. Our findings challenge hyperopia-linked theories of causation. Non-refractive explanations, such as the role of the vergence system, deserve further study. Keywords: accommodation; accommodative esotropia; binocular vision; consecutive exotropia; hyperopia; refractive errors; tonic convergence