We present a rare case of a 9-year-old child with acute accommodative comitant esotropia, a form of acquired strabismus caused by excessive smartphone use. Symptoms commonly include double vision, closing or covering one eye when working at close range and tilting the head or its unnatural position to correct visual abnormalities; however, there are also patients without any symptoms. As part of the differential diagnosis it is necessary to exclude any eye diseases or refractive errors and it is highly recommended to carefully exclude pathologies of the central nervous system and intracranial disorders. In absolute numbers seen so far in real life, acute accommodative comitant esotropia is still a rare phenomenon and the relation to smartphone use might be suspected only after all other etiologies have been excluded. Acute accommodative comitant esotropia is mostly a temporary disorder and corrective glasses are usually sufficient for treatment. The present case demonstrates that forming a completely new type of visual disorder related to modern technologies is possible, even in age groups of children where this is a rare occurrence.