Causality in the systems era of pediatric ophthalmology: The Buddha's smile

PURPOSE: To identify the inherent complexities in assigning causation in the evolving systems era of pediatric ophthalmology. DESIGN: Philosophical analysis of causality as it pertains to understanding the pathogenesis of pediatric strabismus and nystagmus. METHODS: Review of general philosophical problems and profession-related differences in assigning causality as they apply to current controversies in pediatric ophthalmology. RESULTS: Medicine is evolving into a systems era based on a complex network of interacting components including internal systems, gene expression, behavioral factors, and environmental factors. In this context, any definition of cause (epidemiologic, mechanical, physiologic, environmental, genetic, epigenetic, etc.) becomes a function of one's reference point. Thus, as medical science becomes more precise, causality seems to recede. Most current controversies in pediatric ophthalmology are reducible to simple questions of cause and effect. Strabismus and nystagmus often develop without apparent cause, providing a formidable challenge to deciphering disease pathogenesis and assigning causality. In these conditions, assigning causation is impeded by a tendency to confuse links and correlations with cause and effect, an inherent tendency to conflate form and function, the use of terminology that transposes cause and effect, and by our tendency to think linearly about problems that are fundamentally circular. CONCLUSIONS: Our tendency to think linearly creates a self-referential system that influences our understanding of cause and effect. Neural activity is characterized by feedback loops and bidirectionality. Understanding neurodevelopmental strabismus and nystagmus requires a dynamic, circular view of causality.