Acute acquired comitant esotropia in the smartphone era: a narrative review.

PURPOSE: Acute acquired comitant esotropia (AACE) has received increasing attention in the smartphone era, following numerous clinical reports suggesting an association with intensive and prolonged device use. However, it remains unclear whether smartphone use is a direct cause of AACE, a trigger in susceptible individuals, or a surrogate marker for broader modern lifestyle changes that may contribute to its pathogenesis. STUDY DESIGN: Focused narrative review. METHODS: This article presents a focused narrative review of the literature on AACE in relation to intensive smartphone or other handheld digital-display use, with an emphasis on clinical evidence, exposure characteristics, potential sources of bias, and biologically plausible mechanisms. RESULTS: Most of the available evidence comes from retrospective studies and uncontrolled visual hygiene trials, both of which are often limited by selection bias and inaccurate self-reporting of screen time. In addition, publication bias is a major concern; cases mentioning smartphone use may be more likely to be published than otherwise similar cases without reported smartphone exposure. CONCLUSIONS: Prolonged near-viewing on handheld digital displays is a biologically plausible contributing factor to AACE in some patients, particularly through sustained high vergence demand at short viewing distances. Nevertheless, current data are insufficient to establish a population-level causal relationship. Future studies should incorporate objective exposure metrics, standardized phenotyping, and explicit adjustment for age, refractive error, and objectively assessed near-work load to clarify the strength and nature of this association.