Non Surgical Consecutive Exotropia Causal Mechanisms Evade Researchers

Non surgical consecutive exotropia, which occurs in both accommodative and non accommodative childhood esotropia, does not have any identifiable predictive factors, and refractive management of the condition only produces a modest result, according to research published in the American Journal of Ophthalmology.

Researchers included 49 children (mean age, 3.5 years at time of esotropia; mean age, 8.4 years at time of non surgical consecutive exotropia) in a retrospective observational case series to examine clinical characteristics of the disorder and assess its response to conservative management. The team performed a search of hospitals and private clinical practices for pediatric patients (aged 6 months or older) with an esotropia diagnosis who converted to exotropia at either 1/3 or 6 meter fixation distance without surgical intervention and collected baseline demographic and cycloplegic refraction data.  

Overall, participants converted to non surgical consecutive exotropia a mean 4.9 years (range, 0.8 – 15.3 years) after esotropia diagnosis. Accommodative esotropia occurred in 60% of participants cases and 35.7% had high hyperopia (>+5.00 diopters [D]). Nearly all patients (98%) presented with exotropia at distance, the report shows. 

Clinicians reduced prescriptions by a mean 1.55 D to manage non surgical consecutive exotropia in 36.2% of the cohort. The remaining 63.8% of study participants continued to wear their current prescription or a prescription within 0.50 D of their cycloplegic refraction. A total of 43% of study participants underwent exotropia surgery, and refractive management did not affect this outcome, according to the report.

Although the investigation identified clinical features of non surgical consecutive exotropia, it was unable to determine predictive factors for the disorder or methods of causation.

“While the literature has mainly focused on establishing the clinical profile of [non surgical consecutive exotropia], there remains a lack of understanding as to the underlying causal mechanism(s),” the study authors explain. “There is no accepted theory as to why, given otherwise similar clinical presentations, some esotropias spontaneously drift to exotropia while most do not.”

Study limitations include a retrospective nature and lack of uniformity in patient follow-up intervals and data collection. 

Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.